Investigation of electrical properties of organophosphazene layer based photodiode

Article abstract of DOI:10.1016/j.chemphys.2020.110897

New cyclotriphosphazene compound bearing dioxyphenylcoumarin group (DCP-1) was synthesized from the reactions of 7,8-dihydroxy-3-(4-chlorophenyl)coumarin (3) containing chlorine as a side group at para position with cyclotriphosphazene (DCP). The structures of the compounds were determined using ¹H, ¹³C APT, ³¹P NMR, FT-IR and elemental analysis spectroscopy methods. The organic layer was deposited onto the p-Si substrate to obtain an Al/p-si/phosphazene (DCP-1)/Al diode. The photoresponse and photocapacitance properties of the diode were analyzed under various solar light intensities. The photocurrent and photocapacitance results suggest that the studied device exhibits both photodiode and photocapacitor behavior. The diode indicates a linear photoresponse behavior. The photoswitching behavior of the diode is controlled by solar light intensity. The interface states density of the diode was found to be order of 10¹² eV^-1cm². The value of interface states density indicates that the photocapacitor behavior of the diode is significant for photocapacitor applications.

Full text of DOI:10.1016/j.chemphys.2020.110897

ChemicalPhysics538(2020)110897
Contents lists available at ScienceDirect
Chemical Physics
journal homepage: www.elsevier.com/locate/chemphys
Investigation of electrical properties of organophosphazene layer based
photodiode
⁎
Kenan Korana, , Bilal Arifb, Dilawar Alic, Ayşegül Dereb, Furkan Özend,
Abdullah G. Al-Sehemie,f,g, A. Al-Ghamdih, Ahmet Orhan Görgülüa, Fahrettin Yakuphanoğluh,b
a Department of Chemistry, Faculty of Science, Firat University, 23169 Elazığ, Turkey
b Physics Department, Firat University, 23119 Elazığ, Turkey
c Department of Physics, GC University Lahore, 54000, Pakistan
d Department of Mathematics and Science, Akdeniz University, Antalya, Turkey
e Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413 P.O. Box 9004, Saudi Arabia
f Research Center for Adv. Materials Science, King Khalid University, Abha 61413, P.O. Box 9004, Saudi Arabia
g Unit of Science and Technology, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004, Saudi Arabia
h Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
A R T I C L E I N F O
A B S T R A C T
Keywords:
New cyclotriphosphazene compound bearing dioxyphenylcoumarin group (DCP-1) was synthesized from the reac-
tions of 7,8-dihydroxy-3-(4-chlorophenyl)coumarin (3) containing chlorine as a side group at para position with
cyclotriphosphazene (DCP). The structures of the compounds were determined using 1H, 13C APT, 31P NMR, FT-IR
and elemental analysis spectroscopy methods. The organic layer was deposited onto the p-Si substrate to obtain an
Al/p-si/phosphazene (DCP-1)/Al diode. The photoresponse and photocapacitance properties of the diode were
analyzed under various solar light intensities. The photocurrent and photocapacitance results suggest that the studied
device exhibits both photodiode and photocapacitor behavior. The diode indicates a linear photoresponse behavior.
The photoswitching behavior of the diode is controlled by solar light intensity. The interface states density of the
diode was found to be order of 1012 eV-1cm2. The value of interface states density indicates that the photocapacitor
behavior of the diode is significant for photocapacitor applications.
Bandgap
Electrical properties
Cyclotriphosphazene
Coumarin-phosphazene
1. Introduction
electron-providing benzene ring and the electron-attracting pyron ring, the
benzo-α-pyron and its structural isomer, the benzo γ-pyron. Fluorescence
Cyclic phosphazenes [hexachlorocyclotriphosphazene (N3P3Cl6;trimer)
compounds are functionalized with various substituents. Cyclic phospha-
zene compounds have many advantages such as ease of functionalization,
planar structure and stabilization of functionalized cyclic phosphazene
core under heavy chemical conditions [1]. In addition, they are electro-
nically inert so that the side groups accounting for tunability can display
their own electronic and optical properties. Electronic and sensor systems
can be fabricated using cyclic phosphazene compounds due to their in-
teresting electronic and optical properties. The cyclotriphosphazene
compounds can be used in various applications such as capacitors [2,3],
flame retardants [4], organic light emitting diodes and fluorescence sensor
[5–7] and OFET properties [8], and rechargeable lithium batteries [9]. On
the other hand, the coumarin ring is a heterocyclic compound with ef-
fective photophysical properties such as large Stokes shifts and high
quantum yields and it has two various structures: the merger of the
emission of the coumarin compound has been observed due to the inter-
action of dipole–dipole [10–13]. It is well known that electron attracting/
donating groups are attached to the various positions of the coumarin ring
to increase the fluorescence properties. Fluorescence behavioral tendency
is increased by attaching electron-attracting groups (heterocyclic aromatic
or Cl, CN, CF3, etc.) to the 3 and 4-position of coumarin compounds
[14–17]. Coumarin compounds are an important part of organic hetero-
cyclic dyes and compounds used in sensor technology due to their high
optical properties, high light stability, high quantum yield, wide Stokes
shift and low toxicity. Due to these features, coumarin compounds are
highly used in optical brighteners, light emitting diodes, laser paints, dye
sensitive solar cells, biological imaging, nonlinear optical (NLO) chromo-
phores, electrolysis materials, solar collectors and two photon absorption
(TPA) materials [18–26]. New type of cyclophosphazene derivatives can
be synthesized using the coumarin both as a substituent and the trimeric
⁎ Corresponding author.
E-mail address: kkoran@firat.edu.tr (K. Koran).
https://doi.org/10.1016/j.chemphys.2020.110897
Received 16 February 2020; Received in revised form 26 May 2020; Accepted 8 June 2020
Availableonline13June2020
0301-0104/©2020ElsevierB.V.Allrightsreserved.

K. Koran, et al.
ChemicalPhysics538(2020)110897
phosphazen as a skeleton in a molecule to obtain lead to new physico-
chemical properties. There have been studies on physical properties of
new phosphazene and polyphosphazene derivatives which are found in
this literature [27–33]. Najla et al. [34] have demonstrated that coumarin:
GO (graphene oxide) doped Bi2O3 exhibits photocapacitor behavior and
the photoconductance has been improved due to the coumarin: GO doping
under the solar irradiation. This study indicates that the coumarin can be
used as a photodopant to improve photoresponse properties of metal
oxide.
(DMSO‑d6):δ 143.74 C1, 134.51 C2, 150.32 C3, 113.37 C4, 119.84 C5,
113.16 C6, 142.46 C9, 121.08 C10, 160.36 C11, 132.23 C12, 130.52 C13
,
128.63 C14, and 133.08 C15
.
2.2.2. Synthesis procedure of DCP-1
A mixture of DCP (0.3 g, 0.52 mmol) and Na2CO3 (0.22 g,
2.08 mmol) was prepared in a reaction flask (150 mL) using 40 mL of
anhydrous xylene (mixture of isomers). 0.52 mmol compound 3 dis-
solved in 25 mL of xylene and added to the reaction mixture dropwise
at 0 0C. After 25 min at 0 0C, the reaction mixture was refluxed for 48 h.
When reaction was completed, it was subjected to filtration and then
liquid phase evaporation. The obtained solid part was dissolved in xy-
lene (10 mL) and precipitated in n-hexane (250 mL). After the filtration
process, desired product DCP-1 was obtained by column chromato-
graphy separation as a white solid [37]. Yield = 36% (0.14 g). Anal.
Calc. for C39H23ClN3O8P3 (MW = 790 g/mol): C, 59.30; H, 2.93; N,
5.32. Found: C, 59.51; H, 2.98; N, 5.37%. FT-IR (KBr, cm−1): 3065 νC-H
(Aromatic), 2928 νC-H(Aliphatic), 1741 νC=O, 1476, 1493, 1578, and 1633
With this connection, we synthesized the coumarin-bound cyclo-
phosphazenes to fabricate a photodiode. Up to now, there is no any
study on photodiode based on the cyclophosphazene derivative con-
taining the dihydroxyphenylcoumarin compound bearing chlorine as
side group at para position. Chlorine and other species like (–F, –OCH3,
–NH2, –CH3, –OH etc) are known as ortho and para directors. These
electron rich species donate their electrons to carbon chain causing
resonance delocalizing double bond in benzene structure and thus
electrophile is directed towards ortho and para positions due to higher
electron density in these directions.
νC=C, 1175 and 1190 νP=N, 974 νP-O-Ph
.
31P NMR (CDCl3) δ/ppm: 36.62
Therefore, firstly, 7,8-dihydroxy-3-(4-chlorophenyl)coumarin (3)
compound has been synthesized from the interaction of Pyr.HCl with
phenylacrylonitrile compound (2) in silica gel filler using a microwave
oven. Then the new dioxyphenylcoumarin substituted cyclotripho-
sphazene compound (DCP-1) has been synthesized from the interaction
of compound 3 with DCP. The structures of 2, 3 and DCP-1 compounds
were confirmed by using spectroscopy methods. After chemical char-
acterization of DCP-1 sample, we fabricated a Al/p-si/phosphazene
(DCP-1)/Al device for solar tracking systems. The photoelectric and
photocapacitance properties of the diode was analyzed in detail.
(2P, t, PA(O2C12H8)), 24.56 (1P, d, PB(O4C16H10)). 1H NMR (CDCl3) δ/
ppm: 7.18–7.75 (23H, m, H3-6, H12,13, H17,18). 13C NMR (CDCl3) δ/ppm:
147.80 C1, 125.54 C2, 128.74 C3, 129.90 C4, 130.09 C5, 121.74 C6,
140.25 C7, 135.01 C8, 132.88 C9, 116.14 C10, 122.37 C11, 108.79 C12
140.01 C13, 128.51–128.66 C14, C16 and C19, 158.73 C15, 126.47 C17
,
,
129.80 C18
.
2.3. Device fabrication
To fabricate the device, the p-Si was cleaned by the RCA method.
For this purpose, the native oxide layer was removed at first by using
HF etching and then, the substrate was placed in deionized water for
5 min in an ultrasonic bath. Subsequently, the Si substrate was washed
for 5 min each in an ultrasonic bath of methanol and acetone and then
finally dried by nitrogen gas for device fabrication. The back contact
was thermally formed by evaporating the Al metal onto the substrate
and annealing at 570 ℃ for 5 min under the nitrogen environment. The
DCP-1 solution was drop cast onto the p-Si substrate to form the organic
layer and dried for 15 min at 50℃. The top contact was formed by
evaporating Al metal through the mask. The I-V (current–voltage) and
capacitance–voltage (C-V) characteristics of the fabricated diode were
determined at room temperature using a FYTRONIX electronic device
characterization system (ECS-9000), as shown in Fig. 3.
2. Experimental details
2.1. Materials and methods
HCP (hexachlorocyclotriphoshphazene) was purchased from TCI
Chemicals Company. The 2,2′-dihydroxybiphenyl and sodium carbo-
nate were provided from Merck/Sigma Aldrich, respectively. Pyr.HCl
(Pyridine hydrochloride) was purchased from Merck. The solvents re-
quired for the reaction and purification steps were purchased from
Merck. 31P, 1H, and 13C NMR analysis were processed in a Bruker DPX
400 MHz spectrometer. Chloroform‑d1 and Dimethylsulphoxide-d6
solvents were used as deuterium solvent. The FT-IR analyses were
measured on a Perkin Elmer FT-IR spectrometer.
3. Results and discussion
2.2. Synthesis
3.1. Synthesis of the compound
2.2.1. Synthesis of 3
Compound 2 (1 g, 3.03 mmol), an appropriate silica gel (15 g) and
Pyr.HCl (5.2 g, 45 mmol) was mixed in a shilenk tube under the argon
atmosphere. The mixture was stirred at 320 W in FYRONIX microwave
oven for half an hour. The reaction mixture was acidified by adding of
1 N HCl (150 mL) when it’s temperature is cooled to room temperature.
The residue was filtered through silica gel after the precipitated part
dissolved in acetone (3 × 30 mL). The liquid part of the product was
removed under reduced pressure and obtained the solid part, which was
then washed several times with water and thereafter dried under a
vacuum. The crude product was subjected to precipitation using ethyl
acetate (15 mL) in n-hexane. The final purification step was column
chromatography (chloroform:hexane) to obtain target product 3 as a
gray solid [35,36]. Yield = 63% (0.56 g). Anal. Calc. for C15H9ClO4
(MW: 288.68): C, 62.41; H, 3.14; Found C, 62.46; H, 3.19%. FT-IR (KBr,
cm−1): 3197, 3398 νO-H, 3000, 3090 νC-H(Ar), 2917, 2857 νC-H(Al), 1660
The synthesis of compound 3 was achieved in the presence of silica
gel by the reaction of compound 2 with pyridinium hydrochloride in
non-solvent conditions under a microwave irradiation [35,36]. To ob-
tain DCP-1, 1.1 equiv. of compound 3 and DCP were reacted in dry
xylene (a mixture of isomers) and Na2CO3. The structural character-
ization of DCP-1 was provided by 1H, 13C-APT, 31P NMR, elemental
analysis, and FT-IR spectroscopy. The general synthetic scheme for all
the compounds is shown in Scheme 1.
The -C^N peaks of compound 2 was disappeared in FT-IR spectra of
3. A clear evidence for the formation of compound 3 is the conversion
of –OCH3 groups to –OH that showed OH stretching vibration at 3197
and 3398 cm−1, respectively. The C]O stretching vibrations of the
coumarin compound was appeared at 1660 cm−1. Another evidence for
the formation of compound 3 is the disappearance of –OCH3 protons at
1H NMR spectrum of 3. 1H, 13C-APT and 2D HETCOR NMR spectra of 3,
as shown in Fig. 1. In Scheme 1, number 7 and 8 phenolic –OH protons
were resonated at 9.41 and 10.19 ppm.
νC=O, 1563, 1571, 1621 νC=C
.
1H NMR (400 MHz, DMSO‑d6): δ
6.85–6.87 (1H, d, J = 8.4 Hz, H4), 7.11–7.13 (1H, d, J = 8.4 Hz, H5),
7.50–7.52 (2H, d, J = 8.8 Hz, H13), 7.75–7.77 (2H, d, J = 8.4 Hz, H14),
8.17 (1H, s, H9), 9.41 (1H, s, H7), 10.19 (1H, s, H8). 13C NMR
The disappearance of OH stretching vibrations and –OH peak in 1H
NMR spectra of DCP-1 indicates the conversion of compound 2. The
2

K. Koran, et al.
ChemicalPhysics538(2020)110897
Scheme 1. Synthetic Scheme and Numeration of each P, H and C atom at comp. 3 and DCP-1.
aromatic –CH stretching frequency at 3065 cm−1 was observed for
DCP-1. The frequency at 1741 cm−1 belongs to the carbonyl group of
DCP-1 . The characteristic P]N stretching frequencies for phosphazene
compounds were observed at 1175 and 1190 cm−1. The PeOePh
reverse current. This means that the diode exhibited a rectifying be-
haviour. The measure of the rectifying behaviour is defined as ideality
factor, which can be extracted from the slope of the linear region of ln
(I)–V plot and is expressed as follows [41],
stretching vibration was seen at 977 cm−1
.
The 31P, 1H, and 13C-APT NMR spectra for DCP-1 are shown in
Fig. 2 (A2B system). The existence of two distinct 31P peaks have con-
firmed the formation of DCP-1. Two different phosphorus peaks for
DCP-1 were observed at 24.56 and 36.62 ppm in a doublet-triplet, re-
spectively.
q
dV
kT d(ln I)
n =
(2)
The ideality factor using the above equation was found to be 6.46.
The ideality factor value greater than unity shows the non-ideal beha-
viour of the diode. This non-ideality behaviour arises from the existence
of surface states between silicon and an organic layer, non-homogeneity
of the height of Schottky barrier, silicon dioxide layer and series re-
sistance.
The detailed information of 1H and 13C NMR spectra for DCP-1 was
given in the experimental section. 13C peak of DCP-1 carbonyl was
observed at 158.73 ppm. Proposed structures were verified by both
proton integral heights in the 1H NMR and the existence of primary,
secondary and tertiary carbon atom peaks in 13C-APT NMR.
Ocaya et al. [42] have fabricated the substituted coumarin doped
fullerite organic photodiode. They have reported the ideality factor for
the doped samples ranged from 1.65 to 5.86 (20% coumarin doped).
Mekki et al. [43] have reported the ideality factor from 3.97 to 9.52 for
various graphene oxide doped methylene blue photodiode, Al/p-Si/GO
doped MB/Au. These results indicate that organic layer has an im-
portant effect on electronic parameters of the diodes. The organic layer
creates a series resistance and in turn, the ideality factor increases.
In order to use studied diode as photodiodes in optoelectronic ap-
plications, we need to know the photoconductive or photovoltaic be-
havior of the diode. For this, the diode should be analyze the photo-
response behavior under various light intensity conditions. The
following relation can be used to analyze the photoresponse behavior
[44,45].
3.2. Current-voltage (I-V) characteristics of the diode
Fig. 5 shows the forward and reverse I-V characteristics of the Al/p-
Si/organic layer/Al under various solar light intensities. The I-V char-
acteristics of the diode were analysed using the thermionic emission
theory. In this theory, the relationship between current and voltage is
expressed by the following [38–40],
q(V IRs)
q(V IRs )
I = Io
1
exp
nkT
kT
(1)
where k is the Boltzmann constant, V is the applied bias voltage, and T
is the temperature.
Iph = APm
(3)
As seen in Fig. 4, the reverse current of the diode increases with
solar light intensity, whereas the forward current did not change with
solar light. The change in reverse current is due to the separation of
electrons and holes at reverse bias, as the separation of charge carries a
reverse bias region is significant more than the separation at forward
bias region. The forward current of the diode is highly higher than the
where P is the illumination intensity, A is the constant, and m is the
constant whose value can be found by plotting a graph between pho-
tocurrent log(Iph) and illumination intensity log(P) as shown in Fig. 5
and the value of m is found to be 0.26. This value of m suggests the
sublinear behavior of the photoresponse.
3

K. Koran, et al.
ChemicalPhysics538(2020)110897
Fig. 1. (A) 1H NMR; (B) 13C-APT; and (C) 2D HETCOR NMR spectrum of 3 (DMSO‑d6).
3.3. Transient characteristics of the diode
conductance-voltage characteristics were studied. The dependence of
capacitance on frequency and voltage is shown in Fig. 8a. As seen in
Fig. 8a, the capacitance doesn’t change with frequency at positive
voltage. However, capacitance shows a peak at a negative voltage and
the height of this peak decreases with an increase in frequency. At low
frequencies, the charge carrier can respond to the applied signal and
results in high capacitance. The capacitance was adjusted with series
resistance and it is seen in Fig. 8b that the adjusted capacitance CADJ
exhibits peak. The peak position shifts from low frequency to high
frequency. This change suggests that the charge carriers at interface of
the diode follows the frequency of alternating current and in turn, in-
terface states are formed.
Fig. 6 shows the transient photocurrent characteristics of the diode
for photoresponse analysis. As soon as the solar light was switched on
the diode, the photocurrent of the diode increases immediately to a
certain value due to the photo charge pairs generation. When the light
was switched off the photocurrent comes back to its initial value be-
cause the extra-generated free charge carriers are not available for
conduction. The transient photocurrent characteristics of the diodes
indicate that the diode can be optically switched by solar light.
In addition, the photocapacitance response of the diode was mea-
sured and the transient photocapacitance characteristics are given in
Fig. 7. The photocapacitance value increases with the increase in solar
light intensity and it drops back to its original level when the light is off.
This sudden change in capacitance with change in illumination in-
tensity confirms the photocapacitor behaviour. The diode exhibited the
highest photocapacitance at 10 KHz and under the illumination in-
tensity 100 mW/cm2. Hence, our device can also be used as a photo-
capacitor. A similar photo capacitance response has been noted in one
of our previous report [46], where cyclotriphosphazene substituted
with dioxyphenylcoumarin with methyl group at meta position was
used to fabricated the photodiode. The I-V characteristics of Al/HCP-2/
p-Si/Al diode shows higher rectification ratio and a stronger photo
capacitance effect was observed.
This decrease in peak capacitance is attributed to the incapability of
the interface charge carriers to follow the high frequency of AC (al-
ternating current) signal. The effect of frequency and voltage on con-
ductance was measured and shown in Fig. 9. The figure shows that the
conductance does not indicate any important change at positive vol-
tage, whereas, the conductance value increases with both an increase in
frequency and voltage at a negative side. The existence of interface
states is the obvious cause of dispersive capacitance. The series re-
sistance, density of interface states and formation of insulator layer
cause the nonlinear behaviour in capacitance voltage and conductance
voltage characteristics curves. Thus, the corrected capacitance voltage
and conductance voltage with a series resistance effect is given by the
following relation [47–49],
3.4. Capacitance–voltage and Conductance–voltage characteristics
(Gm2 + ( Cm)2)Cm
Cadj
=
a2 + ( Cm)2
(4)
To investigate the junction behaviour, the capacitance–voltage and
4

K. Koran, et al.
ChemicalPhysics538(2020)110897
Fig. 2. (A) 31P NMR; (B) 1H NMR; and (C) 13C-APT NMR spectrum of DCP-1 (in CDCl3).
Fig. 3. Schematic diagram of the Al/p-si/phospha-
zene (DCP-1)/Al fabricated device.
Fig. 5. Photoresponse plot between lnP vs. lnIph of the Al/p-si/phosphazene
(DCP-1)/Al diode.
Fig. 4. Current-voltage characteristics of the Al/p-si/phosphazene (DCP-1)/Al
diode under various illumination conditions.
5

K. Koran, et al.
ChemicalPhysics538(2020)110897
Fig. 6. Transient response of the Al/p-si/phosphazene (DCP-1)/Al diode.
Fig. 7. Transient photocapacitance response of the diode.
Fig. 8. Capacitance plots of the Al/p-si/phosphazene (DCP-1)/Al diode a) C-V
b) Cadj-V.
(Gm2 + ( Cm)2)a
a2 + ( Cm)2
Gadj
=
(5)
diode [51]:
where, Cm and Gm are determined by impedance analyser and a is de-
(Gadj
)
max
2
Dit
=
termined by
2
qA [(Gmax Cox
)
+ (1 Cm Cox )2]
(8)
a = Gm (Gm2 + ( Cm)2)Rs
(6)
Where Cox is the capacitance of the interlayer. The value of interface
states density (Dit) was calculated and is given in Dit vs V plot as shown
in Fig. 11. It can be seen clearly in Fig. 11 that the Dit is decreased with
the frequency and then becomes constant at a lower frequency range.
This behavior caused due to the low response of the interface state
densities at high frequencies. High Dit values are the main cause for the
non-ideal result for the I–V and C–V characteristics of the diode.
where Cadj is the adjusted capacitance, Gadj is the adjusted conductance
and Rs is the series resistance. The conductance G and adjusted con-
ductance Gadj dependence of applied voltage and frequency are shown
in Fig. 9a and b, respectively.
The presence of peak in capacitance and conductance plots is due to
series resistance. Thus, the series resistance value for the diode is cal-
culated by using the following relation [47,50].
Gm
RS
=
4. Conclusions
Gm2 + ( Cm)2
(7)
Fig. 10 shows the frequency dependence of series resistance. The
Phosphazene (DCP-1) based photodiode was fabricated in this
study. The photocapacitance and photoconductance behaviors of the
phosphazene (DCP-1) based diode were investigated. The ideality
factor value shows a non-ideal I-V behavior of the diode. The transient
photoconductance analysis shows that the device can be utilized as a
photocapacitor. The interface state charges play an important role and
modify the capacitance and conductance values of the diode. Adjusted
capacitance and conductance were determined due to the series re-
sistance effect. Finally, the effects of applied AC signal frequency on
interface states inside the organic layer were investigated. It was found
these states significantly modify the C-V and G-V behavior of the diode.
The obtained results suggest that the phosphazene (DCP-1) based
photodiode can be used as photosensor in solar tracking systems.
peak series resistance decreases with the increase in applied AC signal
frequency. An excess resistance at low frequency is observed due to the
interface states following the low frequency signal, which results in a
peak formed in the capacitance voltage graph, as shown in Fig. 10. The
peak intensity is changed with frequency. The magnitude of the peak is
decreased with increasing frequency. This behaviour is due to the
numbers of interface charge carriers. The decrease in magnitude of the
series resistance peak is related to the charge carriers following fre-
quency. The interface charge carriers form the interface states at the
interface of the diode. The interface states affect the diode properties.
Thus, it is important to determine the interface states for the studied
diode. The following relation gives the density of interface states for the
6

K. Koran, et al.
ChemicalPhysics538(2020)110897
Fig. 11. Density interface states dependence on frequency.
Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influ-
ence the work reported in this paper.
Acknowledgements
The synthesis and characterization of compounds were supported by
Research Fund of TUBITAK under project number 110T652. The elec-
trical and photodiode measurements of this work were supported by
Scientific Research Projects Coordination Unit of Firat University under
project number KRMYO.16.01. Authors would like to acknowledge the
support of the King Khalid University for this research through a grant
RCAMS/KKU/007-18 under the (Research Center for Advanced
Materials Science) at King Khalid University, Kingdom of Saudi Arabia.
Fig. 9. Conductance plots of the Al/p-si/phosphazene (DCP-1)/Al diode a) G-
V b) Gadj-V.
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CRediT authorship contribution statement
Kenan Koran: Visualization, Formal analysis, Writing - review &
editing. Bilal Arif: Formal analysis. Dilawar Ali: Data curation.
Ayşegül Dere: Formal analysis. Furkan Özen: Formal analysis.
Abdullah G. Al-Sehemi: Data curation. A. Al-Ghamdi: Data curation.
Ahmet Orhan Görgülü: Supervision, Project administration. Fahrettin
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