Benzoselenadiazole-Based Conjugated Molecules: Active Switching Layers with Nanofibrous Morphology for Nonvolatile Organic Resistive Memory Devices

Article abstract of DOI:10.1002/cplu.202000229

In this work, two symmetrical donor-acceptor-donor (D-A-D) type benzoselenadiazole (BSeD)-based π-conjugated molecules were synthesized and employed as an active switching layer for non-volatile data storage applications. BSeD-based derivatives with different donor units attached through common vinylene linkers showed different electrical and optical properties. 4,7-Di((E)-styryl)benzo[c][2,1,3]selenadiazole (DSBSeD) and 4,7-bis((E)-4-methoxystyryl)benzo[c][2,1,3]selenadiazole (DMBSeD) are sandwiched between gallium-doped ZnO (GZO) and metal aluminum electrodes respectively through solution-processed spin-coating method. The solution-processed nanofibrous switching layer containing the DMBSeD-based memory device showed reliable memory characteristics in terms of write and erase operations with low SET voltage than the random-aggregated DSBSeD-based device. The nanofibrous molecular morphology of switching layer overcomes the interfacial hole transport energy barrier at the interface of the DMBSeD thin-film and the bottom GZO electrode. The memory device GZO/DMBSeD/Al based on nanofibrous switching layers shows switching characteristics at compliance current of 10 mA with V_set=0.79 V and V_reset=?0.55 V. This work will be beneficial for the rational design of advanced next-generation organic memory devices by controlling the nanostructured morphology of active organic switching layer for enhanced charge-transfer phenomenon.

Full text of DOI:10.1002/cplu.202000229

A Multidisciplinary Journal Centering on Chemistry
Accepted Article
Title: Benzoselenadiazole-Based Conjugated Molecules: Active
Switching Layers with Nanofibrous Morphology for Nonvolatile
Organic Resistive Memory Devices
Authors: Apurba K Das, Rohit G. Jadhav, Amitesh Kumar, Sanjay
Kumar, Sayan Maiti, and Shaibal Mukherjee
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
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to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemPlusChem 10.1002/cplu.202000229
Link to VoR: https://doi.org/10.1002/cplu.202000229
01/2020

10.1002/cplu.202000229
ChemPlusChem
Benzoselenadiazole-Based Conjugated Molecules:
Active Switching Layers with Nanofibrous
Morphology for Nonvolatile Organic Resistive
Memory Devices
Mr. Rohit G. Jadhav,[a] Dr. Amitesh Kumar,[b] Mr. Sanjay Kumar,[b] Mr. Sayan Maiti,[a] Dr.
Shaibal Mukherjee[b] and Dr. Apurba K. Das[a]*
[a]Department of Chemistry, Indian Institute of Technology Indore, Indore 453552, India
[b]Hybrid Nanodevice Research Groubandgapp (HNRG), Electrical Engineering, Indian Institute
of Technology Indore, Madhya Pradesh, 453552, India
E-mail: apurba.das@iiti.ac.in
ABSTRACT
In this work, two symmetrical donor-acceptor-donor (D-A-D) type benzoselenadiazole (BSeD)-
based π-conjugated molecules were synthesized and employed as an active switching layer for
non-volatile data storage application. BSeD-based derivatives with different donor units attached
through common vinylene linker showed different electrical and optical properties. 4,7-Di((E)-
styryl)benzo[c][2,1,3]selenadiazole
(DSBSeD)
and
4,7-bis((E)-4-
methoxystyryl)benzo[c][2,1,3]selenadiazole (DMBSeD) sandwiched between Ga-doped ZnO
(GZO) and metal (Al) electrodes respectively via solution-processed spin-coating method. The
solution-processed nanofibrous switching layer containing DMBSeD based memory device
showed reliable memory characteristics in terms of write and erase operations with low SET
voltage than the random aggregated DSBSeD-based device. The nanofibrous molecular
morphology of switching layer overcomes interfacial hole transport energy barrier at the
interface of the DMBSeD thin-film and the bottom GZO electrode. The memory device
GZO/DMBSeD/Al based on nanofibrous switching layer shows switching characteristics at
compliance current of 10 mA with Vset = 0.79 V and Vreset = -0.55 V. This work will be
beneficial for the rational design of advanced next-generation organic memory devices by
controlling the nanostructured morphology of active organic switching layer for enhanced charge
transfer phenomenon.
1
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1. INTRODUCTION
Organic electronics is one of the emerging field of advanced electronics.[1],[2],[3],[4] Organic
material offers molecular structure-dependent optoelectronic properties with low-cost
fabrication, high scalability and novel self-assembly properties over inorganic materials.[5],[6]
From the past few decades, several applications of organic material-based electronic devices
have been developed by worldwide researchers such as light-emitting diodes,[7] flexible
electronic displays,[8] sensors[9] and solar cell devices.[10] The organic resistive random access
memory (O-RRAM) devices have provided an alternative approach for data storage using
organic materials.[11],[12] O-RRAM displays data storage characteristics with the help of different
conductive states of active organic materials under the influence of the external electric field.[13]
The active organic material switches from the low conduction state to high conduction state at a
particular threshold switching voltage under the applied electric field.[14] The variation in
electrical conduction state of organic materials can be considered as electrically ON and OFF
phenomena commonly used for conventional binary data storage devices.[13],[15–17] In recent
years, numerous memory devices based on organic materials including biomaterials such as
enzymes,[18] natural polymers like silk fibroin[19] synthetic materials like organic conjugated
polymers,[20] metal-organic ligand coordination complexes,[21],[22],[23],[24] and small organic
molecules[25],[26] have been reported. Small organic molecules with π-conjugated backbones have
gained considerable attention as a potential organic semiconductor material in recent time.[27],[28]
Small conjugated molecules have a considerable advantage over the conjugated polymers for
their easier synthetic and purification procedures, high structural flexibility, ease in processing
and unaltered reproducibility.[12],[29] Small structural and functional alterations in small
conjugated molecules result in a significant change in optoelectronic properties, intra- and inter-
molecular interactions as well as supramolecular packing.[30],[31],[32] The data storage performance
of conjugated molecules based O-RRAM depends on various factors such as molecular structure,
optoelectronic properties, switching layer morphology. A series of conjugated donor-acceptor
molecule with an identical crystal structure and similarly oriented film state exhibits different
memory characteristics.[33] Thiophene and furan containing heteroacenes were designed and
synthesized which showed typical bipolar resistive switching behavior.[34] Many attempts have
been made to investigate the mechanism and achieve enhanced performance of the O-RRAM
with the help of molecular structure change[35] and device fabrication methods.[36],[37] Yet these
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non-volatile memory devices need more improvement for implementing them as commercial
data storage applications in any form.[38]
Organic material-based thin-films are commonly employed to play the active role of a
semiconducting layer in O-RRAM devices.[39] The performance of such memory devices
depends on charge carrier mobility in the organic semiconductor layer. Similarly, the
supramolecular interactions, stacking properties and thin-film morphology influence the
electronic properties of organic switching layer as well as organic electronic device
performance.[40],[41] Applied external electric field generates free charges having short diffusion
length of ∼10 nm at the interface between donor and acceptor material.[42] Among those charges,
electrons move towards acceptor and positively charged holes move into the donor material. The
nanostructured morphology of switching layer shortens the charge carriers pathway.[43] These
supramolecular nanostructures on thin-film act as natural charge trapping and charge conduction
domains.[42] The nanostructured domains show synergistic charge conduction characteristics for
the improvement of device performance similar to that of the polymer and nanoparticle-based
materials.[40],[44] Performance of small molecule-based devices can be improved by altering
molecular packing and film morphology. In literature, few studies have been reported on the
effect of the morphology of active organic materials towards the suitable alterations in the
resistive memory switching characteristics.[40],[45] The variation of electron-donating units
attached to benzoselenadiazole changes optoelectronic properties as well as self-assembling
pattern in the solid-state.[46] In this report, we have synthesized two benzoselenadiazole based
donor-acceptor-donor (D-A-D) type conjugated molecules with different donor groups with
vinylene linker. The simple sandwiched O-RRAM device based on Ga-doped ZnO(GZO, bottom
electrode)/ organic active compound/ Al (top electrode)has been fabricated and investigated.
Dual ion beam sputtering[47] (DIBS) technique was used to grow GZO against commonly used
ITO for the bottom electrode. Use of DIBS for the growth of GZO facilitates controlling the
properties of GZO by varying the deposition parameters such as substrate temperature, oxygen to
argon ratio during the growth process. Using GZO against ITO is not only economical but also
its deposition by DIBS ensures controlled electronic properties to ensure efficient switching
layer/electrode characteristics for stable switching behavior.[47] The experimental observations
and theoretical studies demonstrate exotic trends of the device performances based on solution-
processed switching layer morphology.
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2. RESULTS AND DISCUSSION
Compounds DSBSeD and DMBSeD were synthesized using Heck C-C coupling reaction
(Figure 1a). In DMF solution, 4,7-dibromo benzoselenadiazole (DBBSeD) was treated with the
corresponding styrene and 4-methoxy styrene in the presence of K2CO3 and palladium acetate
(II) as a catalyst at 110°C to prepare DSBSeD and DMBSeD, respectively.
Al electrode
V
Org. Layer
GZO
Glass
Figure 1. (a) The synthetic route for DSBSeD and DMBSeD. (b) Scheme of the organic
switching layer-based memory device fabricated with aluminium (Al) top and GZO glass bottom
electrode.
DSBSeD and DMBSeD were soluble in DCM, THF and ortho-dichlorobenzene, which suggests
easy film-forming processability with the help of the spin-coating method. The thermal stability
of the molecules was investigated by thermogravimetric analysis (TGA) under the N2
atmosphere (Figure S2). Thermal analysis reveals that the decomposition temperatures of the
DSBSeD and DMBSeD with 5% weight-loss are nearly 260°C and 308°C, respectively.
DMBSeD shows higher thermal stability than DSBSeD. The stable behavior of both compounds
at higher temperature ensures that molecular structure of the compounds will not be affected due
to local heating generated during device operation.
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2.1. Photophysical properties
UV-Vis spectroscopy was used for the analysis of the molecular electronic properties in solution
and solid thin-film state. As shown in Figure 2a, in dichloromethane solution, dual-band
absorption spectra are observed for both compounds, which are characteristic of the donor-
acceptor system.[48] The conjugated backbone present in both the molecules results in π-π*
transition, which is responsible for the higher energy absorption band at 340 nm and 344 nm for
DSBSeD and DMBSeD, respectively. The absorption maxima (λmax) of the higher-energy band
for both DSBSeD and DMBSeD are observed to be very close. The intramolecular charge
transfer from electron-donor to electron-acceptor units is responsible for the lower energy
absorption band at 478 nm and 500 nm for DSBSeD and DMBSeD, respectively. The presence
of the strong electron-donating methoxy (-OCH3) group on the donor unit in DMBSeD is
responsible for the redshift of the lower-energy charge transfer band compared to DSBSeD. The
red-shift in DMBSeD is attributed to the increase in electron density in the conjugated donor-
acceptor system, which results in enhanced intramolecular charge transfer. The edge absorption
wavelengths (λedge) of DSBSeD and DMBSeD appear at approximately 554 nm and 590 nm,
respectively. The optical bandgap (Egoptical = 1240/λedge) of DSBSeD and DMBSeD derived from
the absorption onsets of the compound solutions are calculated as 2.23 eV and 2.10 eV
respectively.
DSBSeD Solution
DMBSeD Solution
DSBSeD Thin Film
DMBSeD Thin Film
(b)1.0
0.5
1.0
0.5
0.0
(a)
0.0
300
400 500
Wavelength (nm)
600
300
400
500
600
700
800
Wavelength (nm)
Figure 2. (a)UV-Vis spectra of DSBSeD and DMBSeD in CH2Cl2 solution. (b) Solid-state UV-
Vis spectra of the spin-coated thin-films of DSBSeD and DMBSeD on quartz substrates
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Compared to solution-state absorption spectra, the absorption spectra in the solid thin-film state
(Figure 2b) show broadened and red-shifted peaks. The broad red-shifted dual-band absorption
spectra may result from the morphology developed by supramolecular aggregation of the
molecules in the solid film state. The ordered self-assembly induced by intense inter and
intramolecular interactions such as π-π stacking interaction increases polarizability of the films,
which can contribute to the enhancement of the charge conduction in the thin-films.[49]
2.2. Morphological properties
Topological atomic force microscopy (AFM) and scanning electron microscopy (SEM) were
used to reveal the nanostructural morphology of the solution-processed DSBSeD and DMBSeD
thin-films. As shown in Figure 3(a, b), topological AFM images of the DSBSeD and DMBSeD
thin-films show distinct morphological behavior. The solution-processed thin-film of the
DMBSeD exhibits nanofibrous network with the root-mean-square (RMS) roughness of 11.22
nm. DMBSeD based thin-film reveals crosslinked nanofibrous network with an average height of
40 nm (Figure 3d). DSBSeD thin-films show random aggregated morphology with an average
height of 140 nm (Figure 3c) and the RMS roughness of 16.21 nm. The higher RMS roughness
value of DSBSeD relative to the DMBSeD thin-film suggests relatively weak molecular stacking
interaction in DSBSeD thin-film.[50] The nanofibrous molecular packing and random aggregation
in thin-film states may attribute to the broader and red-shifted nature of UV-Vis spectra of
DMBSeD and DSBSeD in the film state. The nanofibrous DMBSeD thin-film can facilitate the
concentration of highly efficient charge carrier transmission channels.[51]
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200.47 nm
150
(c)
(a)
100
50
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
700nm
0.00 nm
Length (µm)
70.39 nm (d)50
(b)
40
30
20
10
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
700nm
Length (µm)
0.00 nm
Figure 3. Tapping-mode AFM topography images of (a) DSBSeD and (b) DMBSeD thin-films.
AFM height profile of (c) DSBSeD and (d) DMBSeD thin-films.
SEM images of solution-processed thin-films of DSBSeD and DMBSeD show random
aggregated and crosslinked nanofibrous structures, respectively (Figure 4a and b). SEM images
of the DMBSeD thin-film show fiber diameter ranges from 60 nm to 150 nm. The individual
fibers further self-assembled to form wider fibrous network. Uniform deposition of active
organic material on substrate is essential for fabrication of sandwiched memory device. SEM
analysis was performed to ensure fully coverage of substrate by thin-film of DMBSeD. The
solution-processed thin-film of DMBSeD (Figure S3a to S3c) shows the formation of
nanofibrous network on substrate at 200 nm as well as 10 μm scale. Thickness of thin-film of
DMBSeD containing nanofibers was measured by cross-sectional SEM analysis. Cross-section
of solution-processed thin-film of DMBSeD (Figure S3d) shows film thickness of 80 nm. The
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surface morphology of solution-processed DMBSeD thin-film shows nanofibrillar networks
similar to AFM characterization results.
(b)
(a)
1 μm
1 μm
4.58°
DSBSeD
DMBSeD
(d)
(c)
5.78
°
23.29
°
11.49
°
27.38
°
10.42°
14.20
°
10
20
30
40
50
10
20
30
40
50
2θ
(degree)
2θ (degree)
Figure 4. SEM images of (a) DSBSeD and (b) DMBSeD thin-films. Wide angle XRD pattern of
(c) DSBSeD and (d) DMBSeD thin-films.
The crystalline properties of DSBSeD and DMBSeD thin-films were investigated using wide
angle X-ray diffraction (XRD) characterization. As shown in Figure 4(c,d), normalized X-ray
diffraction patterns of DSBSeD and DMBSeD thin-films exhibit sharp, high intense peaks at 2θ
= 4.58° and 5.78° respectively, which suggest a high degree of crystallinity and molecular
ordering in both films. Other relatively less intense peaks at 2θ = 10.42° in DSBSeD and 11.49°
in DMBSeD thin-films correspond to 8.48 Å and 7.72 Å respectively which are nearly half of the
intense primary peaks suggesting second order Bragg reflections.[52–54] These results suggest that
both DSBSeD and DMBSeD form ordered layer-by-layer self-assembly in the thin-film state.
Further, DMBSeD exhibits diffraction peak at 2θ = 14.20° corresponding to the interlayer
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spacing of 6.23 Å. Two diffraction peaks at 2θ = 23.29° and 27.38° at DMBSeD thin-film
correspond to d-spacing 3.81 Å and 3.25 Å respectively, which are attributed to intermolecular
π–π stacking interactions. These thin-film XRD results suggest that DMBSeD molecules form
more ordered packing in the thin-film. The thin-film characteristics are efficient for obtaining
highly efficient charge conduction and also for exhibiting good memory properties.[40],[55]
2.3. Electrochemical properties
The cyclic voltammetry (CV) measurements were investigated to reveal the energy levels of both
DSBSeD and DMBSeD. Cyclic voltammogram measurements were performed in the solution of
0.1 molL-1 tetrabutylammonium hexafluorophosphate (TBAP) in anhydrous CH2Cl2, which show
the redox behavior of both the compounds. As shown in Figure 5, the onset oxidation potentials
(Eoxonset) vs. Ag/AgCl appear at 1.10 eV and 0.91 eV for DSBSeD and DMBSeD respectively.
The energy levels of both compounds are calculated with references of ferrocene energy levels
from the following equations,
EHOMO = -(Eoxonset + 4.8 - EFerrocene) … … …(1)
ELUMO = (EHOMO + Eg) … … … … … … … (2)
DSBSeD
DMBSeD
onset
E
= 1.10 eV
ox
onset
E
= 0.91 eV
ox
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Potential (V vs Ag/AgCl)
Figure 5. Cyclic voltammetry (CV) curves of the two compounds in 0.1 M Bu4NPF6/CH2Cl2
solution with glassy carbon as working electrode, Ag/AgCl as the reference electrode and Pt wire
as the counter electrode. The scan rate is 100 mV s-1.
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Table 1. Optical and electrochemical properties of DSBSeD and DMBSeD
ΦGZO
-
ELUM
optical
calcd.[a]
onset
[b]
[c]
λmax λedge Eg
(nm) (nm) (eV)
Eg
Eox
(eV)
EHOMO
(eV)
ELUMO
(eV)
Compound
EHOMO O-ΦAl
(eV)
(eV)
0.81
0.62
(eV)
1.02
1.08
DSBSeD
340
344
554
590
2.23
2.10
2.38
2.20
1.10
0.91
-5.51
-5.32
-3.28
-3.22
DMBSeD
[a]Obtained by DFT calculations using B3LYP/6-31G basic set as shown in Figure 7. [b]The
HOMO energy levels were calculated from CV onset oxidation potential (Eox) with the help of
Eq. 1. For calibration, the absolute redox potential of ferrocene/ferrocenium (Fc/Fc+) is assumed
to be -4.80 eV to vacuum, while the external Fc/Fc+ redox standard potential (EFerrocene) is
measured as 0.39 eV vs. Ag/AgCl under the identical conditions (Figure S4).[c]Calculated from
equation 2.
As shown in Table 1, Highest Occupied Molecular Energy Orbital (HOMO) energy levels of
DSBSeD and DMBSeD are calculated as -5.51 eV and -5.32 eV, respectively, resulting from
higher stability toward air oxidation. The low HOMO energy levels are also beneficial for hole
transfer from the GZO electrode with the work function of -4.7 eV. The lowest unoccupied
molecular orbital (LUMO) energy levels are estimated as -3.28 eV and -3.22 eV for DSBSeD
and DMBSeD respectively from equation 2. The substitution of electron-donating group on
donor group provides electron density to electron acceptor benzosenenadizole units which results
in the lower bandgap of DMBSeD as compared to DSBSeD. As shown in Table 1, the hole
injection energy barrier between the work functions of GZO (ΦGZO=-4.7 eV) and HOMO of the
active layer of DSBSeD and DMBSeD are calculated as 0.81 eV and 0.62 eV, respectively. The
electron injection energy barrier (the difference between the work function of Al (ΦAl =-4.3 eV)
between and ELUMO of the molecules) of Al (-4.3 eV) and LUMO of the active layer of DSBSeD
and DMBSeD are found as 1.02 eV and 1.08 eV respectively. Interfacial hole injection from
GZO to the HOMO level of the active organic material is more convenient than the electron
injection from Al metal to the LUMO level of compounds. Therefore, charge conduction in both
molecules DSBSeD and DMBSeD are facilitated through hole injection mechanism suggesting
the p-type semiconductor characteristics.
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2.4. Resistive memory characteristics
The resistive switching characteristics of DSBSeD and DMBSeD based memory devices were
studied using the current-voltage (I–V) characterization. During I-V measurement, bottom
electrode GZO was kept grounded, whereas differential biases were applied to the Al top
electrode. The effect of compliance current on resistive switching characteristics of organic
resistive memory devices are examined by applying different compliance current and different
bias window. Both DSBSeD and DMBSeD based memory devices display bipolar switching
with well-defined flash memory characteristics at different compliance current (Figure 6 and
Figure S5). The I-V curves in Figure S5 suggest the ohmic nature of contact between metal (Al)
and organic layers in both organic memory devices. GZO/DSBSeD/Al memory device shows
hysteresis loop with memory characteristics at optimized compliance current of 20 mA and 30
mA (Figure 6a). Initially, at applied 20 mA compliance current on applying positive sweep from
0 to 2.5V (sweep 1), the GZO/DSBSeD/Al memory device initially in low conductive state (OFF
state) remains the same till bias reached a threshold voltage 1.29 V termed as “SET” voltage
(Vset) (Figure 6b). At Vset, the conductance of the device abruptly changes, and device migrates
from low conductive state (OFF state) to high conductive state (ON state). This phenomenon
corresponds to the ‘‘write’’ process for a memory cell. During the second positive scan (sweep
2), the device remained in the ON state which corresponds to “read” process in the memory
cell.[56] The device maintained ON state even if it is not subjected to any bias for a time-interval.
The results suggest non-volatile data-storage characteristics and state remains consistent even as
bias 0 to -1.5 V (sweep 3) is applied. As the device is applied a negative sweep from -1.5 to 0 V
(sweep 4), the device remains in the high conductive state till it reaches a threshold voltage -
1.13V, termed as “RESET Voltage” (Vreset), where device resets or switches from ON to OFF
state. The RESET phenomenon corresponds to “erase” process in the memory cell.[56] This
write–read-erase switching with non-volatile behaviour corresponds to flash memory
characteristics.[56],[57] The organic memory device GZO/DSBSeD/Al based on random aggregates
containing switching layer shows stable switching characteristics at two cycles of potential
sweeps at compliance current of 20 mA with Vset = 1.29 V and Vreset = -1.13 V (Figure 6b).
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However, the GZO/DSBSeD/Al memory device requires higher voltage for Vset and Vreset
process at higher compliance. I-V characteristics of GZO/DMBSeD/Al at higher bias voltage and
compliance current were performed under similar conditions.
Next, the fabricated DMBSeD thin-films containing GZO/DMBSeD/Al memory device
was characterized. The hysteresis loops of DMBSeD based memory device shows stable
performance on cyclic voltage sweeps at compliance current of 10 mA. (Figure 6c) The device
initially shows low conductive state till bias reached Vset at around 0.84 V for sweep 1 (0 to 1.5
V). After five cycles of bias sweep Vset voltage stabilized at 0.79 V (Figure 6d). At Vset, device
changes from low conductive to high conductive state corresponding to device transition from
OFF to ON state. Similar to DSBSeD based device, DMBSeD based device maintained the ON
state even as bias was removed for a time-interval and was again applied. It similarly suggests
that the device exhibits non-volatile memory characteristics. Afterwards, for reverse negative
sweep ON state continues till it reaches Vreset= -0.55 V. The memory device GZO/DMBSeD/Al
based on nanofibrous switching layer shows switching characteristics after five cycles at
compliance current of 10 mA with Vset = 0.79 V and Vreset = -0.55 V (Figure 6d). The behaviour
of device in whole switching cycle confirms the similar write–read-erase switching behaviour as
DSBSeD based device with flash memory characteristics.
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0.1
(b)
(a)0.1
GZO/ DSBSeD/ Al
V
reset
0.01
0.01
1E-3
1E-4
V
set
1E-3
1E-4
1E-5
10 mA
20 mA
30 mA
50 mA
1st cycle
2nd cycle
GZO/ DSBSeD/ Al
-2 -1
Compliance current = 20 mA
0
1
2
-2
-1
0
1
2
Voltage (V)
Voltage (V)
(c)0.1
GZO/ DMBSeD/ Al
V
(d)
reset
0.01
1E-3
1E-4
1E-5
V
set
0.01
1E-3
1E-4
1E-5
1st cycle
2nd cycle
3rd cycle
4th cycle
5th cycle
10 mA
50 mA
100 mA
Compliance current = 10 mA
-1.5 -1.0 -0.5 0.0
GZO/ DMBSeD/ Al
-3 -2 -1
0.5
1.0
1.5
0
1
2
3
Voltage (V)
Voltage (V)
Figure 6. I-V characteristics of (a) GZO/DSBSeD/Al at different compliance current (b)
GZO/DSBSeD/Al at 20 mA compliance current, (c) GZO/ DMBSeD/Al at different compliance
current and (d) GZO/DMBSeD/Al at 10 mA compliance current.
Also, any memory device should exhibit low Vset/ Vreset voltages for low operating power losses.
The higher Vset of DSBSeD (1.29 V) device as compared to DMBSeD (0.79V) may be attributed
to the higher bandgap of DSBSeD (2.23 eV). The fibrous morphology of DMBSeD on the
electrode decreases the charge transfer energy barrier at interfacial surfaces of the electrode and
facilitates the migration of charge carriers through the films at lower operating voltages. We may
optimize DMBSeD layer in future for even better switching characteristics. We have fabricated
30 devices each using DSBSeD and DMBSeD as a switching layer. The observed switching
probability of GZO/DMBSeD/Al memory devices was higher than GZO/DSBSeD/Al devices.
The GZO/DMBSeD/Al and GZO/DMBSeD/Al memory devices show 38% and 23% of device
yield respectively. The thickness of organic layer was controlled by the rotations per minute
during the spin coating procedure. The memory devices with increased thickness of organic layer
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showed absent of contact between organic layers and top Al electrode during I-V measurements.
However, devices fabricated with low thickness of organic layer displayed diffusion top Al
electrode to bottom GZO electrode.
2.5. Proposed memory mechanism
Many switching mechanisms, such as metal-filament formation[58] and charge-trapping[59] have
been considered to investigate the non-volatile resistive switching mechanism of the O-RRAM
devices. Several literature references of organic memory devices imply that the switching
phenomenon is independent of the filament conduction between top Al electrode and bottom
electrode.[60],[61] The electrical transitions from OFF state to ON state were intrinsic to the
organic switching layer rather than the formation of metal filament during the resistive
switching.[61] The theoretical calculations were carried out to gain insight into different switching
performance of the non-volatile memory device. The B3LYP/6-31G basic set in the Gaussian 09
program gives insights into the optimized molecular energy structure and ground state geometry.
According to density functional theory (DFT) calculations, the π-conjugated molecular surface of
molecules has positive molecular electrostatic potential (ESP) shown in reddish-yellow color
(Figure 7). The positive ESP region serves as an open channel for charge carriers throughout the
π-conjugated molecular surface.[50] However, the blue coloured negative ESP region serves as
“charge traps” to block the motion of charged species.[62] Introduction of electron-donating –
OCH3 results in DMBSeD molecular surface providing more π-conjugated charge conduction
pathways compared to the conjugated backbone of the DSBSeD molecular surface. At applied
low voltage bias, the device remains in initial low conduction state (OFF) because of the
presence of charge injection energy barrier, which blocks the charge conduction from donor to
acceptor. As applied voltage increases, the charge carriers gained adequate energy to inject from
acceptor to donor units which result in filling of charge trapping sites.[63] As charge traps are
filled, it further results in intra- as well as intermolecular charge transport. The intra- and
intermolecular charge transport switches memory device from OFF to ON state.[64],[65] Possible
electron transport from donor to acceptor induces molecular energy excitation from the HOMO
to LUMO energy state. The molecular charge transfer may form stable charge-separated state to
maintain ON state attributing to non-volatile nature of memory device. However, device
switches from the high-conductive state (ON) to low conductive state (OFF) for applied reverse
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bias due to dissociation of charge-separated state. This explains flash memory behaviour in the
memory devices based on DSBSeD and DMBSeD.
(a)
ESP
(b)
-3.22eV
e+
-3.28eV
-4.30eV
Al
LUMO
HOMO
-4.70eV
h+
-5.32eV
-5.51eV
DSBSeD
DMBSeD
Figure 7. (a) Molecular simulation results of DSBSeD and DMBSeD: Electrostatic potential
(ESP), and HOMO and LUMO molecular orbitals. (b) Energy level diagram of the charge
transfer process in DSBSeD and DMBSeD molecules-based memory devices.
The optimized HOMOand LUMO molecular orbital surface of the DSBSeD and DMBSeD
molecules were shown in Figure 7a. Both molecules show planar configuration, which is
suitable for ordered packing behavior in the films. The electron density in HOMO was localized
at the electron donor side and the LUMO was confined at the benzosenadiazole acceptor unit.
From theoretical DFT calculations, the bandgap energy for the DSBSeD and DMBSeD
compounds are calculated as 2.38 eV and 2.20 eV respectively. To understand the different
switching performance ofDSBSeD and DMBSeD based devices, an energy level diagram is
shown in Figure 7b. The work function of DIBS grown GZO (-4.70 eV) is near to the HOMO
energy levels of switching layer molecules (-5.51 eV and -5.32). The energy barrier for
positively charged hole injection process from GZO to the molecular HOMO level of the
compounds is lower than that for electron injection barrier from Al to the LUMO level of the
compounds. The charge migration energy difference suggests that the effect of hole injection
process dominates over the electron injection process for charge conduction under negative
bias.[65] However, the hole injection barrier for DMBSeD is smaller than that of DSBSeD, which
can contribute to lower threshold SET voltages for DMBSeD based data storage device. Further,
the introduction of vinylene linker between donor and acceptor also helps in increasing the
planarity of molecular backbone. The planner molecular structure generates ordered molecular
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packing and arrangement in the solid thin state. The self-assembled molecular domain forms the
charge carrier transport pathways and reduces the charge injection energy barriers. This helps in
lowering Vset of DMBSeD which facilitates lower operating power requirements for O-RRAM
device.
2.6. Comparative analysis of different organic-switching layer-based memory devices
Table 2 provides an overview of organic memory devices consisting of the nanostructure-based
organic-switching layer. Several researchers have used ITO[30] as the bottom electrode while
low-cost GZO fabricated by novel DIBS method has been deployed as the bottom electrode to
have control over electronic properties of switching-layer/electrode interface. Al is economical
as compared to generally used electrodes such as Pt[22] and Au[66] electrodes. Small structural
change in active organic molecule leads alteration in thin-film morphology and optoelectronic
properties of active organic material. The processing condition of active organic layer also
affects the morphology and crystallization of organic layer which affects the transport and
retention of charge carriers.[4],[67] π-Conjugated triazole derivatives were used to fabricate organic
memory devices.[30] The triazole derivatives have shown distinct thin-film morphology which
leads to different memory characteristics such as dynamic random access memory (DRAM),
write once read many times (WORM) and flash memory with different Vset/ Vreset voltages. Non-
volatile WORM memory provides the advantage over DRAM as it can store data even as the
power shuts down. In another example, amphiphilic metal-organic complexes were synthesized
which self-assemble in fibrous architectures through the π−π stacking interactions. The
complexes containing switching layer displayed SRAM (static random access memory) property
with Vset at 3.4 V. Memory behaviour varies from device to device according to the underlying
mechanism prevailing due to the switching material used and corresponding electrode/switching
layer combination. Rod-coil diblock copolymer self-assembled into nanorod morphology and the
switching layer containing nanorods showed unipolar write-read-erase-reread (WRER) similar to
flash memory characteristics with relatively high Vset/ Vreset (4V/ 7 V).[68] Flash memories show
superior data storage application over DRAM and WORM due to its non-volatile rewritable
memory characteristics. As shown in Table 2, memory devices with different organic layers
illustrate various memory characteristics with different Vset/ Vreset voltages. In this report, two
benzoselenadiazole based donor-acceptor-donor (D-A-D) type conjugated molecules with
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different donor groups with vinylene linker have been synthesized. The simple sandwiched O-
RRAM device based on Ga-doped ZnO (GZO, bottom electrode)/ organic active compound/ Al
(top electrode) has been fabricated and investigated. The I-V measurement shows that DSBSeD
and DMBSeD based memory devices display bipolar switching with well-defined flash memory
characteristics at different compliance current. The GZO/DSBSeD/Al memory device shows
hysteresis loop with memory characteristics at optimized compliance current of 20 mA and 30
mA (Figure 6a). The GZO/DSBSeD/Al organic memory device based on random aggregates
containing switching layer shows switching characteristics at compliance current of 20 mA with
Vset = 1.29 V and Vreset = -1.13 V (Table 2). The GZO/DMBSeD/Al memory device based on
nanofibrous switching layer shows switching characteristics at compliance current of 10 mA
with Vset = 0.79 V and Vreset = -0.55 V. The lower bandgap and nanofibrous morphology of
DMBSeD synergically lowers Vset voltage with high switching performance flash memory
characteristics as compared to DSBSeD and other reported devices.[30],[22]
Table 2. Comparative analysis of different organic memory devices containing distinct organic
switching layer morphology
Switching
Layer
Morphology
Sr. Bottom
No. Electrode Electrode Layer
Top
Switching
Memory
Type
Vset/ Vreset
Ref.
1.
2.
GZO
ITO
Au
Al
MoO3/m-CP Aggregate
WORM 1.5 V
51
52
P3HT44-b-
Nanorod
POXD18
WRER
4 V/ 7V
HATT
HDTT
HETT
HRTT
1-PPN
DSBSeD
Network
Aggregate
Grain-like
Aggregate
Fibers
WORM -4.3 V
Flash
-4.0 /4.1 V
3.
4.
5.
ITO
ITO
GZO
Al
Pt
20
16
WORM -4.2 V
DRAM
SRAM
Flash
-3.9 V
3.4 V
Aggregate
1.29/-1.13 V
In
this
work
Al
DMBSeD
Nanofibers
Flash
0.79/-0.55 V
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3. CONCLUSION
In summary, two π-conjugated BSeD-based molecules DSBSeD and DMBSeD with same
electron acceptor unit and different electron donor units were synthesized. DBSeD and DMBSeD
were utilized as an active switching layer in organic memory devices. The fabricated memory
devices with organic switching layers exhibit non-volatile rewritable flash memory type data-
storage properties. Topological AFM and SEM characterizations were used to investigate the
morphological behavior of solution-processed switching layers. The self-assembled
nanostructures in switching layers help to i) lower the bandgap of the thin-film, ii) act as charge
trapping layer, iii) broaden the active charge carrier transport area. The suitable charge trapping
and conduction mechanism have been proposed with the help of theoretical and experimental
results to explain the non-volatile binary flash memory characteristics. Against commonly used
ITO electrode, low-cost GZO as fabricated by novel DIBS method has been deployed as the
bottom electrode to control switching-layer/electrode interface properties. Our results
demonstrate the effect of thin-film morphology on memory performance which may provide a
new strategy to develop in data storage performance of O-RRAMs.
4. EXPERIMENTAL METHODS
4.1. Materials
All starting reagents and chemicals were obtained commercially and used without further
treatment. o-Phenylenediamine, palladium (II) acetate and styrene were purchased from Alfa
Aesar (Thermo Fisher Scientific) whereas 4-methoxystyrene and tetrabutylammonium
hexafluorophosphate (TBAPF6) were purchased from TCI chemicals (India) Pvt. Ltd. Anhydrous
Ag2SO4, Na2SO4, celite 545 and tetrabutylammonium bromide (TBAB) were purchased from
SRL chemicals, India. Hexane, dichloromethane (DCM), chloroform, tetrahydrofuran (THF) and
N,N’-dimethylformamide (DMF) were purchased from Merck India Ltd. Thin layer
chromatography (TLC, silica gel 60 F254) sheets were obtained from Merck KGaA. DMF and
DCM were freshly dried and distilled for the synthesis and electrochemical studies.
4.2. Instruments and measurements
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1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were recorded on a Bruker AV 400 MHz
spectrometer at 300 K using tetramethylsilane as the internal standard. Compound concentrations
were in the range 5-10 mmol L−1 in CDCl3. MALDI-TOF MS analysis was performed on
autoflexTOF using 2,5-dihydroxybenzoic acid (DHB) matrix. UV-vis absorption spectra were
recorded using a Varian Cary100 Bio UV-vis spectrophotometer. The thin-film was prepared
through advanced programmable spin-coating system Apex (Model spinNXG-P1). The surface
roughness and height was measured using the Asylum Research MFP-3D atomic force
microscope. For SEM measurements, thin-films were coated with gold. Then, the images were
recorded on a field-gun scanning electron microscope (Jeol Scanning Microscope-JSM-7600F).
Thin-films were investigated using a Bruker D8 Advance X-ray diffractometer. The X-rays were
produced using a sealed tube, and the wavelength of the X-rays was 0.154 nm (Cu Ka). The X-
rays were detected using a fast counting detector based on silicon strip technology (Bruker
LynxEye detector). The redox properties of synthesized final compounds were studied using
cyclic voltammetry measurements in a dry DCM solution containing 0.1 M TBAPF6. Cyclic
voltammograms were recorded on Metrohm AUTOLAB potentiostat (PG STAT302N) using
three electrode system i.e. glassy carbon as the working electrode, Pt wire as the counter
electrode, and Ag/ AgCl as the reference electrode. The scan rate was 100 mV s−1 for CV
measurements. For theoretical study, density functional theory (DFT) calculations were carried
out at the B3LYP/6-31G level for C, N, Se, H, O in the Gaussian 09 program. The current-
voltage (I-V) characteristics of the device were measured using a Keithley 2612A sourcemeter
and Everbeing probe-station.
4.3. Fabrication of organic resistive memory device
DSBSeD and DMBSeD based O-RRAM devices were fabricated as GZO/organic active
compound/Al sandwiched hetero-structures. The organic layer of thickness 80nm (Figure S3)
was spin- coated on GZO coated glass before depositing the metal electrode as the top electrode
(Figure S3).On top of glass substrate, GZO film was sputtered using DIBS system and employed
as the bottom electrode. DIBS system is equipped with radio-frequency (RF) deposition ion
source and direct-current coupled (DC) assists ion source.[69] As compared to single ion beam
deposition, the film stoichiometry is enhanced in DIBS by mixing oxygen into the working gas
(Ar) in the assist ion source.[70] Other salient features of DIBS is mentioned elsewhere.[69] THF
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solution of DSBSeD and DMBSeD (2 mg/mL) was prepared. Then, 0.05 mL of solution was
spin coated onto the substrates at a spinning speed of 500 rpm for 20 s and then 8000 rpm for 60
s, followed by drying at 50° C for 1 hour. Finally, Al top electrode with a diameter of 500 µm
was patterned on the surface of the switching layer using a metal shadow mask at room
temperature in pure Argon ambience. Figure 1b represents the schematic structure of the
GZO/organic molecule/Al sandwiched memory device.
AUTHOR INFORMATION
Corresponding Author
*E-mail: apurba.das@iiti.ac.in
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
A.K.D. sincerely thanks the Department of Science & Technology, NanoMission, New Delhi,
India (project: SR/NM/NS-1458/2014) for the financial support. S. M. is thankful for the Young
Faculty Research Fellowship (YFRF) under the Visvesvaraya PhD Scheme for Electronics and
Information Technology. This publication is an outcome of the R&D work undertaken in the
project under the Visvesvaraya PhD scheme of Ministry of Electronics & Information
Technology, Government of India, being implemented by Digital India Corporation (formerly
Media Lab Asia). R.G.J. thanks University Grant Commission (UGC), India, for his fellowship.
S. K would like to thank Department of Science and Technology (DST) for providing INSPIRE
fellowship for his doctoral fellowship. A. K. would like to thank Council of Scientific &
Industrial Research (CSIR) for providing fellowship. Authors thank Prof. Ashish Garg, Material
Science Engineering, IIT Kanpur for the AFM facility and the Sophisticated Instrumentation
Centre (SIC), IIT, Indore for providing all other instrumental facility. Authors thank GC-GC-
TOFMS Central Facility of IIT Bombay for MALDI-TOF MS facility.
Keywords: benzoselenadiazole; donor-acceptor systems; nanofibrous morphology; organic
resistive memory; switching devices
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REFERENCES
[1]
[2]
[3]
T. W. Kelley, P. F. Baude, C. Gerlach, D. E. Ender, D. Muyres, M. A. Haase, D. E. Vogel,
S. D. Theiss, Chem. Mater. 2004, 16, 4413.
S. Inal, J. Rivnay, A.-O. Suiu, G. G. Malliaras, I. McCulloch, Acc. Chem. Res. 2018, 51,
1368.
Y. Yu, Q. Ma, H. Ling, W. Li, R. Ju, L. Bian, N. Shi, Y. Qian, M. Yi, L. Xie, W. Huang,
Adv. Funct. Mater. 2019, 29, 1904602.
[4]
[5]
[6]
F. Yang, X. Wang, H. Fan, Y. Tang, J. Yang, J. Yu, Nanoscale Res. Lett. 2017, 12, 503.
B. Cho, S. Song, Y. Ji, T. W. Kim, T. Lee, Adv. Funct. Mater. 2011, 21, 2806.
B. McDearmon, Z. A. Page, M. L. Chabinyc, C. J. Hawker, J. Mater. Chem. C 2018, 6,
3564.
[7]
[8]
[9]
D. Di Nuzzo, C. Kulkarni, B. Zhao, E. Smolinsky, F. Tassinari, S. C. J. Meskers, R.
Naaman, E. W. Meijer, R. H. Friend, ACS Nano 2017, 11, 12713.
S. Choi, S. Kwon, H. Kim, W. Kim, J. H. Kwon, M. S. Lim, H. S. Lee, K. C. Choi, Sci.
Rep. 2017, 7, 6424.
T. Someya, T. Sekitani, S. Iba, Y. Kato, H. Kawaguchi, T. Sakurai, Proc. Natl. Acad. Sci.
2004, 101, 9966.
[10] H. Zhou, L. Yang, W. You, Macromolecules 2012, 45, 607.
[11] C. Wang, P. Gu, B. Hu, Q. Zhang, J. Mater. Chem. C 2015, 3, 10055.
[12] H. Li, Q. Xu, N. Li, R. Sun, J. Ge, J. Lu, H. Gu and F. Yan, J. Am. Chem. Soc. 2010, 132,
5542.
[13] J. C. Scott, L. D. Bozano, Adv. Mater. 2007, 19, 1452.
[14] W. Wang, R. Dong, X. Yan, B. Yang, J. Phys. D. Appl. Phys. 2011, 44, 475102.
[15] M. Das, A. Kumar, R. Singh, M. T. Htay, S. Mukherjee, Nanotechnology 2018, 29,
055203.
[16] M. Das, A. Kumar, B. Mandal, M. T. Htay, S. Mukherjee, J. Phys. D. Appl. Phys. 2018,
51, 315102.
[17] A. Kumar, M. Das, V. Garg, B. S. Sengar, M. T. Htay, S. Kumar, A. Kranti, S.
Mukherjee, Appl. Phys. Lett. 2017, 110, 253509.
[18] H. Wang, F. Meng, B. Zhu, W. R. Leow, Y. Liu, X. Chen, Adv. Mater. 2015, 27, 7670.
[19] Q. Pan, M. Su, Z. Zhang, Z. Cai, Y. Li, Z. Huang, X. Qian, X. Hu, F. Li, H. Dong, Y.
Song, Adv. Electron. Mater. 2019, 5, 1900131.
[20] W. Y. Lee, H. C. Wu, C. Lu, B. D. Naab, W. C. Chen, Z. Bao, Adv. Mater. 2017, 29,
7670.
[21] P. Wang, H. Wang, Y. Fang, H. Li, J. He, Y. Ji, Y. Li, Q. Xu, J. Zheng, J. Lu, ACS Appl.
Mater. Interfaces 2017, 9, 32930.
21
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000229
ChemPlusChem
[22] Y. Li, L. Chen, Y. Ai, E. Y. H. Hong, A. K. W. Chan, V. W. W. Yam, J. Am. Chem. Soc.
2017, 139, 13858.
[23] B. Hu, C. Wang, J. Wang, J. Gao, K. Wang, J. Wu, G. Zhang, W. Cheng, B.
Venkateswarlu, M. Wang, P. S. Lee, Q. Zhang, Chem. Sci. 2014, 5, 3404.
[24] P. Y. Gu, J. Gao, C. J. Lu, W. Chen, C. Wang, G. Li, F. Zhou, Q. F. Xu, J. M. Lu, Q.
Zhang, Mater. Horizons 2014, 1, 446.
[25] Q. Zhang, J. He, H. Zhuang, H. Li, N. Li, Q. Xu, D. Chen, J. Lu, Adv. Funct. Mater. 2016,
26, 146.
[26] C. Wang, B. Hu, J. Wang, J. Gao, G. Li, W. W. Xiong, B. Zou, M. Suzuki, N. Aratani, H.
Yamada, F. Huo, P. S. Lee, Q. Zhang, Chem. Asian J. 2015, 10, 116.
[27] J. Dhar, K. Swathi, D. P. Karothu, K. S. Narayan, S. Patil, ACS Appl. Mater. Interfaces
2015, 7, 670.
[28] Y. Li, C. Zhang, P. Gu, Z. Wang, Z. Li, H. Li, J. Lu, Q. Zhang, Chem. A Eur. J. 2018, 24,
7845.
[29] Q. Liu, C. Zhao, G. Tian, H. Ge, RSC Adv. 2018, 8, 805.
[30] F. Zhou, J.-H. He, Q. Liu, P.-Y. Gu, H. Li, G.-Q. Xu, Q.-F. Xu, J.-M. Lu, J. Mater. Chem.
C 2014, 2, 7674.
[31] S. Debnath, S. Chithiravel, S. Sharma, A. Bedi, K. Krishnamoorthy, S. S. Zade, ACS Appl.
Mater. Interfaces 2016, 8, 18222.
[32] J. Xiao, Z. Yin, Y. Wu, J. Guo, Y. Cheng, H. Li, Y. Huang, Q. Zhang, J. Ma, F. Boey, H.
Zhang, Q. Zhang, Small 2011, 7, 1242.
[33] Z. Liu, J. He, H. Zhuang, H. Li, N. Li, D. Chen, Q. Xu, J. Lu, K. Zhang, L. Wang, J.
Mater. Chem. C 2015, 3, 9145.
[34] G. Li, K. Zheng, C. Wang, K. S. Leck, F. Hu, X. W. Sun, Q. Zhang, ACS Appl. Mater.
Interfaces 2013, 5, 6458.
[35] H. Liu, H. Zhuang, H. Li, J. Lu, L. Wang, Phys. Chem. Chem. Phys. 2014, 16, 17125.
[36] Y. Song, J. Jang, D. Yoo, S. H. Jung, S. Hong, J. K. Lee, T. Lee, Org. Electron. 2015, 17,
192.
[37] X. Hou, X. Xiao, Q.-H. Zhou, X.-F. Cheng, J.-H. He, Q.-F. Xu, H. Li, N.-J. Li, D.-Y.
Chen, J.-M. Lu, Chem. Sci. 2017, 8, 2344.
[38] S. G. Hahm, S. Choi, S. H. Hong, T. J. Lee, S. Park, D. M. Kim, W. S. Kwon, K. Kim, O.
Kim, M. Ree, Adv. Funct. Mater. 2008, 18, 3276.
[39] J. Rivnay, S. C. B. Mannsfeld, C. E. Miller, A. Salleo, M. F. Toney, Chem. Rev. 2012,
112, 5488.
[40] H. Ling, J. Lin, M. Yi, B. Liu, W. Li, Z. Lin, L. Xie, Y. Bao, F. Guo, W. Huang, ACS
Appl. Mater. Interfaces 2016, 8, 18969.
[41] C. Vijayakumar, V. K. Praveen, A. Ajayaghosh, Adv. Mater. 2009, 21, 2059.
[42] V. D. Mitchell, E. Gann, S. Huettner, C. R. Singh, J. Subbiah, L. Thomsen, C. R. McNeill,
22
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000229
ChemPlusChem
M. Thelakkat, D. J. Jones, Macromolecules 2017, 50, 4942.
[43] P. B. Pati, S. P. Senanayak, K. S. Narayan, S. S. Zade, ACS Appl. Mater. Interfaces 2013,
5, 12460.
[44] Q. Zhang, G. Wang, H. Li, F. Zhu, H. Li, J. Lu, Adv. Funct. Mater. 2018, 28, 1800568.
[45] W. Rekab, M. A. Stoeckel, M. El Gemayel, M. Gobbi, E. Orgiu, P. Samorì, ACS Appl.
Mater. Interfaces 2016, 8, 9829.
[46] S. Mondal, M. Konda, B. Kauffmann, M. K. Manna, A. K. Das, Cryst. Growth Des. 2015,
15, 5548.
[47] V. Garg, B. S. Sengar, V. Awasthi, A. Kumar, R. Singh, S. Kumar, C. Mukherjee, V. V.
Atuchin, S. Mukherjee, ACS Appl. Mater. Interfaces 2018, 10, 5464.
[48] P. B. Pati, S. S. Zade, Cryst. Growth Des. 2014, 14, 1695.
[49] Y. Ma, X. Cao, G. Li, Y. Wen, Y. Yang, J. Wang, S. Du, L. Yang, H. Gao, Y. Song, Adv.
Funct. Mater. 2010, 20, 803.
[50] Z. Liu, J. He, H. Zhuang, H. Li, N. Li, D. Chen, Q. Xu, J. Lu, K. Zhang, L. Wang, J.
Mater. Chem. C 2015, 3, 9145.
[51] W. Zhang, C. Wang, G. Liu, X. Zhu, X. Chen, L. Pan, H. Tan, W. Xue, Z. Ji, J. Wang, C.
Yu, R. W. Li, Chem. Commun. 2014, 50, 11856.
[52] H. Usta, C. Newman, Z. Chen, A. Facchetti, Adv. Mater. 2012, 24, 3678.
[53] S. Miao, Y. Zhu, Q. Bao, H. Li, N. Li, S. Ji, Q. Xu, J. Lu, L. Wang, J. Phys. Chem. C
2014, 118, 2154.
[54] P. L. T. Boudreault, J. W. Hennek, S. Loser, R. P. Ortiz, B. J. Eckstein, A. Facchetti, T. J.
Marks, Chem. Mater. 2012, 24, 2929.
[55] Y. Diao, B. C. K. Tee, G. Giri, J. Xu, D. H. Kim, H. A. Becerril, R. M. Stoltenberg, T. H.
Lee, G. Xue, S. C. B. Mannsfeld, Z. Bao, Nat. Mater. 2013, 12, 665.
[56] D. K. Maiti, S. Debnath, S. M. Nawaz, B. Dey, E. Dinda, D. Roy, S. Ray, A. Mallik, S. A.
Hussain, Sci. Rep. 2017, 7, 13308.
[57] J. Xiao, Z. Yin, H. Li, Q. Zheng, F. Boey, H. Zhang, Q. Zhang, J. Am. Chem. Soc. 2010,
132, 6926.
[58] S. Gao, C. Song, C. Chen, F. Zeng, F. Pan, J. Phys. Chem. C 2012, 116, 17955.
[59] Y. Li, H. Li, J. He, Q. Xu, N. Li, D. Chen, J. Lu, Chem. Asian J. 2016, 11, 906.
[60] Y. Li, H. Li, H. Chen, Y. Wan, N. Li, Q. Xu, J. He, D. Chen, L. Wang, J. Lu, Adv. Funct.
Mater. 2015, 25, 4246.
[61] W. Ren, Y. Zhu, J. Ge, X. Xu, R. Sun, N. Li, H. Li, Q. Xu, J. Zheng, J. Lu, Phys. Chem.
Chem. Phys. 2013, 15, 9212.
[62] C. Wang, J. Wang, P. Z. Li, J. Gao, S. Y. Tan, W. W. Xiong, B. Hu, P. S. Lee, Y. Zhao,
Q. Zhang, Chem. Asian J. 2014, 9, 779.
[63] X. F. Cheng, E. B. Shi, X. Hou, S. G. Xia, J. H. He, Q. F. Xu, H. Li, N. J. Li, D. Y. Chen,
23
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000229
ChemPlusChem
J. M. Lu, Chem. Asian J. 2017, 12, 45.
[64] S. Miao, H. Li, Q. Xu, Y. Li, S. Ji, N. Li, L. Wang, J. Zheng, J. Lu, Adv. Mater. 2012, 24,
6210.
[65] Q. Bao, Q. Zhang, Y. Li, H. Li, J. He, Q. Xu, N. Li, D. Chen, J. Lu, Org. Electron. 2016,
28, 155.
[66] X. Wu, H. Xu, Y. Wang, M. Lee, C. Pearson, T. Jung, M. N. Kozicki, H. J. Barnaby, Jpn.
J. Appl. Phys. 2016, 55, 03DC05.
[67] S. Zhou, Q. Tang, H. Tian, X. Zhao, Y. Tong, S. Barlow, S. R. Marder, Y. Liu, ACS Appl.
Mater. Interfaces. 2018, 10, 15943
[68] Y. Fang, C. Liu, C. Li, C. Lin, R. Mezzenga, W. Chen, Adv. Funct. Mater. 2010, 20, 3012.
[69] R. Singh, P. Sharma, M. A. Khan, V. Garg, V. Awasthi, A. Kranti, S. Mukherjee, J. Phys.
D. Appl. Phys. 2016, 49, 445303.
[70] S. G. Yoon, Y. T. Kim, H. K. Kim, M. J. Kim, H. M. Lee, D. H. Yoon, Mater. Sci. Eng. B.
2005, 234.
24
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10.1002/cplu.202000229
ChemPlusChem
Graphical Abstract
V
Nanofibrous thin film
Flash type switching
Low Vset and Vreset
Table of content
In this work, two symmetrical donor-acceptor-donor (D-A-D) type benzoselenadiazole (BSeD)-
based π-conjugated molecules were synthesized and employed as an active switching layer for
non-volatile data storage application. The GZO/DMBSeD/Al memory device based on
nanofibrous switching layer shows switching characteristics at compliance current of 10 mA
with Vset = 0.79 V and Vreset = -0.55 V.
25
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