Synthesis and enhanced electron transfer of supramolecular nano-composite containing dendritic dye and surface-modified ZnO nano-rods

Article abstract of DOI:10.1016/j.dyepig.2018.04.052

Supramolecular nano-composites 15T5N/ZnOx-PNH containing enhanced compatibilities of dendritic dye 15T5N and surface-modified nano-rod ZnOx-PNH were developed in this study. The physical properties of supramolecular nano-composites have been well investigated by theoretical calculation and various measurements, including UV–visible, PL, TEM, TCSPC, FT-IR, and CV. H-bonded nano-composite 15T5N/ZnO₃₀-PNH possessed the saturated quenched fluorscence as dendritic dye 15T5N complexed with surface-modified nano-rod ZnO₃₀-PNH. In contrast to nano-rod mixture 15T5N/ZnO (without surface-modification), more widened visible absorption band to promote more efficient photo-induced charge separation phenomenon was observed in supramolecular nano-composite 15T5N/ZnO₃₀-PNH. Compared with surfactant T-PNH, less efficient electron transfer of surfactant T-PC6 was observed in TCSPC and PL measurements because of the steric hindrance of long alkyl chains (-C₆H₁₃) attached to surfactant T-PC6. Therefore, the triple H-bonds between dendritic dye 15T5N and surface-modified nano-rod ZnO₃₀-PNH are verified to result in the desirable effective electron transfer in supramolecular nano-composite 15T5N/ZnO₃₀-PNH.

Full text of DOI:10.1016/j.dyepig.2018.04.052

Accepted Manuscript
Synthesis and enhanced electron transfer of supramolecular nano-composite
containing dendritic dye and surface-modified ZnO nano-rods
Chien-Min Lin, Ming-Shiou Li, Atul Kumar Dwivedi, Hong-Cheu Lin
PII:
S0143-7208(18)30257-2
10.1016/j.dyepig.2018.04.052
DYPI 6713
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 2 February 2018
Revised Date: 24 April 2018
Accepted Date: 25 April 2018
Please cite this article as: Lin C-M, Li M-S, Dwivedi AK, Lin H-C, Synthesis and enhanced electron
transfer of supramolecular nano-composite containing dendritic dye and surface-modified ZnO nano-
rods, Dyes and Pigments (2018), doi: 10.1016/j.dyepig.2018.04.052.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Graphical abstract:

ACCEPTED MANUSCRIPT
Synthesis and Enhanced Electron Transfer of Supramolecular Nano-Composite
Containing Dendritic Dye and Surface-Modified ZnO Nano-Rods
a
a
a
a,b*
Chien-Min Lin, Ming-Shiou Li, Atul Kumar Dwivedi, Hong-Cheu Lin
a
Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu,
Taiwan
b
*
Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan
Corresponding author. Fax: Int. code +886 (3)5712121.
E-mail: linhc@mail.nctu.edu.tw
Keywords:
Supramolecular nano-composite;
dendritic dye;
surface-modified nano-rod;
zinc oxide (ZnO);
photo-induced charge separation;
electron transfer
1

ACCEPTED MANUSCRIPT
Abstract
Supramolecular nano-composites 15T5N/ZnOx-PNH containing enhanced compatibilities of
dendritic dye 15T5N and surface-modified nano-rod ZnOx-PNH were developed in this study. The
physical properties of supramolecular nano-composites have been well investigated by theoretical
calculation and various measurements, including UV-visible, PL, TEM, TCSPC, FT-IR, and CV.
H-bonded nano-composite 15T5N/ZnO -PNH possessed the saturated quenched fluorscence as
30
dendritic dye 15T5N complexed with surface-modified nano-rod ZnO -PNH. In contrast to nano-rod
3
0
mixture 15T5N/ZnO (without surface-modification), more widened visible absorption band to
promote more efficient photo-induced charge separation phenomenon was observed in supramolecular
nano-composite 15T5N/ZnO -PNH. Compared with surfactant T-PNH, less efficient electron
3
0
transfer of surfactant T-PC6 was observed in TCSPC and PL measurements because of the steric
hindrance of long alkyl chains (-C H ) attached to surfactant T-PC6. Therefore, the triple H-bonds
6
13
between dendritic dye 15T5N and surface-modified nano-rod ZnO -PNH are verified to result in the
3
0
desirable effective electron transfer in supramolecular nano-composite 15T5N/ZnO -PNH.
3
0
2

ACCEPTED MANUSCRIPT
1. Introduction
Due to the broad range of energy bandgaps in zinc oxide (ZnO), ZnO-based semi-conductors
possessing excellent thermal, chemical, and structural properties are considered as attractive materials.
Therefore, ZnO nano-particles (NPs) have been witnessed to be outstanding nano-composite materials
as mixed with organic molecules. These composite materials are superior due to their enhanced
electro-optical properties, chemical stabilities, non-toxicities, bio-compatibilities, and simplicities of
fabrications [1-6]. The various applications of ZnO nano-particles are mainly attributed to their
superior sensitivity, photoluminescence, and electro-optical properties. Because of chemical reactions
between organic and inorganic molecules, such as the thiol (-SH) group of organic molecules attached
to the surface of ZnO, the nano-composites might generate new or promoted physical properties in
contrast to the nature of original ZnO nano-particles [7-9]. In addition, ZnO nano-particles could also
be well surface-modified by surfactants 1-dodecanethiol (DT) and 16-mercaptohexadecanoic acid
(MPA) via the reaction of the thiol group introduced by Chen et al [10]. Due to such advanced
properties, ZnO nano-composites in recent years have been utilized in a considerable number of
applications, such as optical, magnetic, and electronic materials [11,12]. Effective surface
modifications of nano-particles through the functional groups of organic surfactants have also
improved the compatibility of CdSe nano-particles with their organic counterpart, where the total
contact interface area of electron donor (organic) and acceptor (nano-particle) was further enhanced.
Therefore, Locklin et al. successfully applied ligand exchange method to coat the oligo-thiophene
dendrimer on the surface of CdSe nano-particles [13]. Moreover, in addition to the enhanced
solubilities of the derived nano-particles surface-modified with thiophene dendrimers, the enlarged
absorptions of thiophene dendrimers in the visible region improved light-induced charge separation
phenomena and increased power conversion efficiencies in bulky-hetero junction (BHJ) solar cells
[
14-20]. Marczak et al. used surface sol-gel process for the preparation of 5 nm-sized ZnO
nano-particles, which especially utilized the catechol functional group of porphyrinatozinc dye grafted
3

ACCEPTED MANUSCRIPT
to ZnO nano-particles [21]. Thus, both of the increased absorption in the visible region and the
improved effective electron transfer in the contact interface area of ZnO nano-composites were
originated from the organic counterpart (i.e., porphyrinatozinc dye) and the compatibility of ZnO
nano-particles in the organic porphyrinatozinc dye, respectively [22-24].
Fig. 1. Schematic illustration of supramolecular nano-composite (15T5N/ZnO-PNH)
Herein, as shown in Fig. 1 we report the construction of a supramolecular nano-composite system
composed of dendritic thiophene-based dye 15T5N, hydrogen-bonded (H-bonded) surfactant T-PNH
(with a thiol terminus, -SH), and ZnO nano-rods, where T-PNH facilitated the electron transfer
between dye 15T5N and ZnO nano-rods via triple hydrogen-bonds (H-bonds) and a thiol linkage of
T-PNH, respectively. The surface modifications of ZnO nano-rods were introduced by surfactant
T-PNH via the thiol linkage to form surface-modified nano-rods (i.e., ZnO-PNH) not only improved
their effective electron transfer but also enhanced their compatibilities of ZnO-PNH with dye 15T5N.
Attributed to the visible absorption band of dye 15T5N and surfactant T-PNH, the nano-composite
system was widened to possess more efficient photo induced charge separation phenomena. Especially,
the imide group of perylenebisimide
(
PBI)-based surfactant T-PNH was H-bonded with the
4

ACCEPTED MANUSCRIPT
diethylaminotriazinyl group of dye 15T5N to enhance the self-assembly capability between 15T5N
and T-PNH by the formation of triple H-bonds, and thus to shorten the distance between PBI and
dendritic thiophene-based dye 15T5N to meet the electron transfer restrictions. Accordingly, the thiol
terminal group of T-PNH was involved in the covalent bond formation with ZnO nano-rods to observe
the overall electron transfer from dendritic dye 15T5N to ZnO nano-rods via surfactant T-PNH was
visualized.
2. Experimental section
2.1. Materials
The synthetic scheme for some of the dendron precursors and dendritic dye 15T5N is shown in
Scheme 1. The synthetic routes of surface-modified surfactants T-PNH and T-PC6 [25-28] are shown
in Scheme 2. ZnO nano-rods were synthesized by following the literature procedures [29]. Chemicals
and solvents were reagent grades and purchased from Aldrich, ACROS, TCI, and Lancaster Chemical
Co. Toluene, tetrahydrofuran, and diethyl ether were distilled to keep anhydrous before use.
2.2. Measurements and characterization
1
H NMR spectra were recorded on a Varian Unity 300 MHz spectrometer using CDCl solvents.
3
Elemental analyses were performed on a HERAEUS CHN-OS RAPID elemental analyzer.
UV–visible absorption and photoluminescence (PL) spectra were recorded in dilute chlorobenzene
−6
solutions (10 M) on a HP G1103A and Hitachi F-4500 spectrophotometer, respectively. Solid films
of UV–vis and PL measurements were spin-coated on quartz substrates from chlorobenzene solutions
with a concentration of 10 mg/mL. TEM studies were performed using a JEOL 2010 instrument under
an acceleration voltage of 200 kV. The samples were prepared by dispersing in DMF and then
dropping the dispersion onto the TEM copper grids. Time-correlated single-photon counting (TCSPC)
spectra were measured using a home-built single photon counting system. Excitation was performed
using a 375 nm diode laser (Picoquant PDL-200, 50 ps fwhm, 2 MHz). Infrared spectra (FT-IR) were
5

ACCEPTED MANUSCRIPT
investigated by a Perkin-Elmer Spectrum 100 instrument. Cyclic voltammetry (CV) measurements
were performed using a BAS 100 electrochemical analyzer with a standard three electrode
electrochemical cell in a 0.1M tetrabutylammonium hexafluorophosphate (TBAPF ) solution (in
6
chorobenzene) at room temperature with a scanning rate of 50 mV/s. In each case, a carbon working
electrode coated with a thin layer of these copolymers, a platinum wire as the counter electrode, and a
silver wire as the quasireference electrode were used. Ag/AgCl (3M KCl) electrode was served as a
reference electrode for all potentials quoted herein. During the CV measurements, the solutions were
+
purged with nitrogen for 30 s, and the redox couple ferrocene/ferrocenium ion (Fc/Fc ) was used as an
external standard. Each onset potential in the CV measurements was defined by the intersection of two
tangents drawn at the rising current and background current.
2.3. Dendritic dye Synthesis
The synthetic details of these intermediates (including compounds 1-4) have been published in the
literature [13].
2.3.1. Synthesis of tributyl-(5,5'-dihexyl-[2,2';3',2']terthiophen-5''-yl)stannane (5)
Into a 500 mL round-bottomed flask, compound 4 (6 g, 14 mmole), n-BuLi (9 mL, 2.5 M in
hexane, 1.4 eq), tributyltin chloride (9.45 mL, 1.2 eq), and dry THF (150 mL) were added under
nitrogen and reacted for 5 h at -78 °C. After work up, the mixture was extracted with water/EA, and
the organic liquid layer was dried over anhydrous MgSO . After removal of the solvent by
4
evaporation under reduced pressure a yellow liquid was obtained and moved to the next step for the
synthesis of compound 6 directly.
2.3.2. Synthesis of 2,3-di(5,5'-dihexyl-[2,2';3',2']terthiophen-5''-yl)thiophene (6) 7T
Into a 100 mL round-bottomed flask, compound 1 (i.e., 2,3-dibromothiophene, 1.71 g, 0.5 eq),
compound 5 (9.98 g, 14 mmole), 150 mg Pd(PPh ) , and 30 mL DMF were added under nitrogen and
3
4
reacted for 24 h at 100 °C. After work up, the mixture was extracted with water/KF saturated
aqueous to remove salts (tributyltin) and the organic liquid layer was dried over anhydrous MgSO4.
After removal of the solvent by evaporation under reduced pressure, the residue was purified by
6

ACCEPTED MANUSCRIPT
1
column chromatography (hexane/DCM = 50/1) to give an orange liquid product ( 4.43 g, 33%). H
NMR(CDCl , 300 MHz) δ 7.28 (d, 1H, J=5.3 Hz), 7.21(s, 1H), 7.18(s, 1H), 7.17(d, 1H, J=5.3 Hz),
3
6
2
2
7
.94 (d, 1H, J=1.7 Hz), 6.93(d, 1H, J=1.7 Hz), 6.88(d, 1H, 3.5 Hz), 6.86(d, 1H, 3.5 Hz), 6.51(m, 4H),
.76(t, 8H), 1.66(m, 8H), 1.34(m, 24H), 0.88(t, 6H, 6.7 Hz).
.3.3. Synthesis of tributyl{2,3-di(5,5'dihexyl[2,2';3',2']terthiophen-5''-yl)thiophen-5-yl}stannane (7)
T-SnBu3
Into a 500 mL round-bottomed flask, compound 6 (4 g, 4.38 mmole), n-BuLi (2.1 mL, 2.5 M in
hexane, 1.4 eq), tributyltin chloride (2.4 mL,1.2 eq), and dry THF (150 mL) were added under
nitrogen and reacted for 5 h at -78 °C. After work up, the mixture was extracted with water/EA, and
the organic liquid layer was dried over anhydrous MgSO . After removal of the solvent by
4
evaporation under reduced pressure, a dark orange liquid product was obtained and went for the next
step for the synthesis of compound 8 directly.
2.3.4. Synthesis of 2,3-di{2',3'-di(5',5''-dihexyl-[2'',2''; 3'',2'']terthiophen-5'''-yl)thiophen-5-yl)
thiophene (8) 15T
Into a 100 mL round-bottomed flask, compound 1 (i.e., 2,3-dibromothiophene, 0.53 g, 0.5 eq),
compound 7 (5.27 g, 4.38 mmole), 150 mg Pd(PPh ) , and 30 mL DMF were added under nitrogen
3
4
and reacted for 24 h at 100 °C. After work up, the mixture was extracted with water/KF saturated
aqueous to remove salts (tributyltin), and the organic liquid layer was dried over anhydrous MgSO4.
After removal of the solvent by evaporation under reduced pressure, the residue was purified by
1
column chromatography (hexane/DCM = 8/1) to give an orange liquid product (2.25 g, 27%). H
NMR(CDCl , 300 MHz) δ7.33 (d, 1H, J=5.3 Hz), 7.28(s, 1H), 7.24(s, 1H), 7.237(s, 1H), 7.21(s, 1H),
3
7
1
2
.20 (d, 1H, J=5.3 Hz), 7.19(s, 1H), 6.93(m, 4H), 6.84(m, 4H), 6.62(m, 8H), 2.74(t, 16H, J=7.4 Hz) ,
.61(m, 16H), 1.29(m, 48H), 0.88(t, 24H, 5.4 Hz).
.3.5. Synthesis of tributyl-{2,3-di{2',3'-di(5',5''-dihexyl-[2'',2''; 3'',2'']terthiophen-5'''-yl)thiophen-5-
yl)thiophene-yl}stannane (9) 15T-SnBu3
7

ACCEPTED MANUSCRIPT
Into a 500 mL round-bottomed flask, compound 8 (3.5 g, 1.8 mmole), n-BuLi (1 mL, 2.5 M in
hexane, 1.4 eq), tributyltin chloride (1.2 mL,1.2 eq), and dry THF (150 mL) were added under nitrogen
and reacted for 5 h at -78 °C. After work up, the mixture was extracted with water/EA and organic
liquid layer was dried over anhydrous MgSO . After removal of the solvent by evaporation under
4
reduced pressure, a dark orange liquid product was obtained and moved forward the next step for the
synthesis of compound 10 directly.
2
.3.6. Synthesis of (10) 15T5N
Into 100 mL round-bottomed flask, compound
a
9
(3.95 g, 1.8 mmole),
2
,4-bis(ethylamino)-6-chloro-1,3,5-triazine (0.4g, 1.1 eq), 150mg Pd(PPh ) , and 30 mL DMF were
3
4
added under nitrogen and reacted for 24 h at 100 °C. After work up, the mixture was extracted with
water/KF saturated aqueous to remove salts (tributyltin) and the organic liquid layer was dried over
anhydrous MgSO . After removal of the solvent by evaporation under reduced pressure, the residue
4
was purified by column chromatography (hexane/DCM = 5/1) to give an orange liquid product (800
1
mg, 21%). H NMR(CDCl , 300 MHz) δ7.97(s, 1H), 7.32(s, 1H), 7.26(s, 1H), 7.23(s, 1H), 7.22(s, 1H),
3
7.18(s, 2H), 6.89(m, 4H), 6.83(m, 4H), 6.59(m, 8H) 5.12(d, 2H, J=7.2 Hz), 3.49(s, 4H), 2.69(t, 16H,
J=7.4 Hz) , 1.61(m, 16H), 1.29(m, 48H), 0.88(t, 24H, 5.4 Hz). Elemental analysis for 15T5N;
calculated: C, 66.65; H, 6.76; N, 3.38. found: C, 66.13; H, 6.82; N, 3.51. (See Fig. S1 and Table S1.)
2.4. Synthesis of surface-modified surfactant T-PNH
2
.4.1. Synthesis of 3,4,9,10-perylenetetracarboxy-3,4-anhydride potassium salt (12)
Into a 1000 mL round-bottomed flask, 3,4,9,10-perylenetetracarboxydianhydride (11) (10.0 g,
5.5 mmol) was added in 600 ml H O and then KOH (40.0 g, 0.71 mmol in 200ml H O) was added
2
2
2
and stirred to react for 2 h at 90 °C. After work up, 50 ml CH COOH was added in the mixture and
3
stirred for 40 min at 90 °C. After removal of the solvent by evaporation under reduced pressure, the
residue was wash repeatedly with methanol and dry at 100 °C to give a purple product (10 g, 90%).
2.4.2. Synthesis of 3,4,9,10-Perylenetetracarboxylic-3,4-anhydride-9,10-imide (13) PNH
8

ACCEPTED MANUSCRIPT
3,4,9,10-Perylenetetracarboxy-3,4-anhydride potassium salt (12) (1.92 g, 4.30 mmol), amine
(25%, 2 ml), and DI water (60 mL) were mixed and stirred to react at 90 °C for 48 h. After work up,
potassium carbonate (25%, 200 mL) was added and stirred for another 3 h at 90 °C. The precipitate
was collected by vacuum filtration and washed with a mixed solvent of DI water (300 mL) and
triethylamine (10 ml). After acidification with hydrochloric acid (2 M, 500 mL), the precipitate was
collected by vacuum filtration to give a dark red product. The product was purified via sublimation (-3
mbar, 300 °C) to get the final product (0.8g, 40%). MS (MALDI-TOF): matrix (CHC): m/z(%): Calcd
+
for C H NO ; 391.330; found: 391.213 [M] . Elemental analysis for PNH; calculated: C, 73.66; H,
2
4
9
5
2
2
.32; N, 3.58. found: C, 73.80; H, 2.33; N, 3.56. (See Fig. S2 and Table S1.)
.4.3. Synthesis of N-(4-thiophenol)-3,4,9,10-perylenebis-(dicarboximide) (14) T-PNH
3,4,9,10-Perylenetetracarboxylic-3,4-anhydride-9,10-imide (13) (1 g, 2.40 mmol),
4
3
-aminothiophenol (1.2 g, 9.36 mmol), and imidazole (20 g) were stirred under nitrogen at 100 °C for
h. After work up, the mixture was dissolved in ethanol (300 ml)/HCl (2M, 300 ml) and stirred to react
for one day. The PTFE membrane (ADVANTEC 0.45 µm) filter was used to collect a dark red
filtration product (0.8g, 76%). MS (MALDI-TOF): matrix (CHC): m/z(%): Calcd for C H N O S;
3
0
14
2
4
+
4
98.510; found: 498.070 [M] . Elemental analysis for T-PNH; calculated: C, 72.28; H, 2.83; N, 5.62.
found: C, 72.22; H, 2.72; N, 5.58. (See Fig. S3 and Table S1.)
2.5. Synthesis of surface-modified surfactant T-PC6
2.5.1. Synthesis of N-(hexyl)-3,4,9,10-perylenetetracarboxylic-3,4-anhydride-9,10-imide (15) PC6
3
,4,9,10-Perylenetetracarboxy-3,4-anhydride potassium salt (12) (1.92 g, 4.30 mmol), n-hexyl
amine (2.175 g, 21.50 mmol) were added in DI water (60 mL) and stirred to react at 90 °C for 48 h.
After work up, potassium carbonate (25%, 200 mL) was added and stirred for another 3 h at 90 °C. The
precipitate was collected by vacuum filtration and washed with a mixed solvent of DI water (300 mL)
and triethylamine (10 ml). After acidification with hydrochloric acid (2 M, 500 mL), the solvent was
removed by evaporation under reduced pressure, and washed repeatedly with methanol and dry to
9

ACCEPTED MANUSCRIPT
yield a purple product (1.8 g, 90%).
2
.5.2. Synthesis of N-(hexyl)-N’-(4-thiophenol)-3,4,9,10-perylenebis(dicarbox-imide) (16) T-PC6
N-(hexyl)-3,4,9,10-perylenetetracarboxylic-3,4-anhydride-9,10-imide (15) (1.141g, 2.4 mmol),
-aminothiophenol (1.2 g, 9.36 mmol) and imidazole (20 g) were stirred under nitrogen at 100 °C for 3
4
h. After work up, the mixture was dissolved in ethanol (300 ml)/HCl (2M, 300 ml) and stirred to react
for one day. The PTFE membrane (ADVANTEC 0.45 µm) filter was used to acquire a dark red
1
filtration product (0.9g, 80%). H NMR(CDCl , 300 MHz) δ9.82(s,1H), 8.51(m, 8H, perylene),
3
7.60(d, 2H), 7.39(d, 2H), 4.21(t, 2H), 1.71(dd, 2H), 1.25(m, 6H), 0.96(m, 3H). MS (MALDI-TOF):
+
matrix (CHC): m/z(%): Calcd for C H N O S; 582.670; found: 582.054 [M] . Elemental analysis for
3
6
26
2
4
T-PC6; calculated: C, 74.21; H, 4.50; N, 4.81. found: C, 74.13; H, 4.48; N, 5.01. (See Figs. S4-S5 and
Table S1.)
3. Results and discussion
Zinc oxide (ZnO) is a well-established family member of metal oxides, which has their promising
electronic, optical, and piezoelectric properties, and the hybrid nanostructures of ZnO are generally
considered as electron acceptors in conjunction with organic dyes as electron donors. Therefore, the
H-bonded diaminotriazine moiety was connected to oligothiophene dendrimer 15T to form dendritic
dye 15T5N, which has been successfully utilized as a donor in this study (Scheme 1). The synthesis of
the third generation of 15T was performed using thiophene as the starting material following a series
of coupling reactions. We also synthesized perylenebisimide (PBI)-based surfactant T-PNH as shown
in Scheme 2. The perylene core of surfactant must be covalently functionalized with a suitable
anchoring group, i.e., thiol (-SH) group, to generate mixed hybrid systems consisting of perylene
derivatives (T-PNH and T-PC6), which could be linked to ZnO nano-rods (by various weight ratios to
surfactant) via the reaction of thiol (-SH) group with an optimum reaction time of 30 mins.
Consequently, surfactant T-PNH attached to ZnO nano-rods could hold dendritic dye 15T5N and ZnO
1
0

ACCEPTED MANUSCRIPT
Scheme 1. Synthesis of dendritic dye 15T5N.
1
1

ACCEPTED MANUSCRIPT
O
O
O
O
O
O
(11)
1
2
) KOH/H O
2
) CH COOH
3
O
O
HO
HO
O
O
1
2
3
) NH OH
1) n-hexyl amine
4
) K CO
2) K CO3
2
3
2
O
) HCl 2M
3) HCl
(12)
O
HN
O
O
O
N
O
O
O
O
O
O
(13) PNH
(15) PC6
4
-aminothiophenol
4
-aminothiophenol
imidazole /100oC
imidazole /100oC
O
N
O
O
O
HN
O
O
N
O
SH
N
SH
O
(14) T-PNH
(16) T-PC6
Scheme 2. Synthesis of surfactants T-PNH and T-CP6.
nano-rods together via the diethylaminotriazinyl group of dendritic dye 15T5N and the H-bonded
head (imide group) of T-PNH. In order to compare the H-bonded effect of T-PNH, a H-bonded
counterpart T-PC6 was also synthesized by following Scheme 2. Hence, due to the steric hindrance of
a hexyl group on the imide nitrogen of T-PC6, the H-bonded interaction of T-PC6 with dendritic dye
15T5N was expected to be reduced, which could be further proven by the PL quenching and
1
2

ACCEPTED MANUSCRIPT
time-correlated single-photon counting (TCSPC) experiments. In general, dendritic dye 15T5N was
H-bonded to surfactant T-PNH (which was attached to ZnO nano-rods via thiol reaction) to stabilize
the shell structure of the supramolecular nano-composite system.
Since dendritic structures have been used as capping agents and surface modifiers of electron
acceptors in the literature [13], the electron transfer phenomena resulting in fluorescence intensity
changes of dendritic dye 15T5N in the shell structure of the supramolecular nano-composite system
need to investigated. As shown in the UV/Vis spectra (in DMF solution) of Fig. 2(a), ZnO absorption
band was blue shifted from 365 to 360 nm and surfactant T-PNH absorption bands centered at 0-0 and
0-1 transition bands were significantly reduced in the solution of surface-modified nano-rods
ZnOx-PNH, where the subscript x is the weight ratio of ZnO to T-PNH. Moreover, the absorption
band of T-PNH was almost diminished in surface-modified nano-rod ZnO -PNH. As shown in the
3
0
PL spectra (in DMF solution) of Fig. 2(b), the corresponding PL emissions of surface-modified
nano-rods ZnOx-PNH showed different quenching behavior with various weight ratios of ZnO.
Importantly, the maximum quenching PL emission was observed in ZnO -PNH with a weight ratio
3
0
of 30:1. However, lower weight ratios of ZnO in surface-modified nano-rods ZnO -PNH and
2
0
ZnO -PNH showed distinct emissions of T-PNH in Fig. 2(b), which indicated the over-supplies of
1
0
surfactant T-PNH in ZnO -PNH and ZnO -PNH to render the aggregation of surfactant T-PNH, so
20
10
Fig. 2. (a) Absorption, (b) and (c) fluorescence spectra of ZnO, T-PNH, and ZnO -PNH with
X
different weight ratios and different reaction time of T-PNH and ZnO -PNH in DMF. (λex = 350 nm)
1
0
1
3

ACCEPTED MANUSCRIPT
the optimum weight ratio of 30:1, i.e., ZnO -PNH, was preferred to have the largest quenching
3
0
effect. As shown in Fig. 2(c), the corresponding emission bands of surface-modified nano-rod
ZnO -PNH with different reaction time (i.e., 30 sec and 30 min) were quenched to different extents,
1
0
where the weaker PL emission of ZnO -PNH was observed with a longer reaction time at 30 min.
1
0
Hence, the optimum reaction time of 30 mins for nano-rod ZnO and surfactant T-PNH to produce
the saturated quenching of all surface-modified nano-rods (e.g., ZnOx-PNH) was maintained
throughout this study. Accordingly, such significant changes of the UV/Vis and PL spectra of T-PNH
and surface-modified nano-rods ZnO -PNH in Fig. 2 provided the weight ratio and reaction time
X
effects of surfactant T-PNH to ZnO nano-rods via thiol linkage to form various surface-modified
Fig. 3. (a) Absorption and (b) fluorescence spectra of 15T5N, 15T5N/ZnO, and 15T5N/ZnO -PNH
X
with a weight ratio of dendritic dye 15T5N and ZnO nano-rod (or surface-modified nano-rods
ZnO -PNH) = 1:1 for both mixtures in DMF, (c) absorption and (d) fluorescence spectra of 15T5N,
X
1
5T5N/ZnO, and 15T5N/ZnO -PNH with a weight ratio of dendritic dye 15T5N and ZnO nano-rod
X
(
or surface-modified nano-rods ZnO -PNH) = 1:1 for both mixtures in solid films. (λex = 350 nm)
X
1
4

ACCEPTED MANUSCRIPT
nano-rods (i.e., ZnO -PNH) and thus to affect the electron transfer behavior between surfactant
X
T-PNH and ZnO nano-rods as well as the PL properties of surface-modified nano-rods ZnO -PNH.
X
Furthermore, the organic surfactant T-PNH was investigated to validate our hypothesis for the
necessity to induce the electron transfer phenomenon from dendritic dye 15T5N to ZnO nano-rods via
the bridging mediator T-PNH. Therefore, as illustrated in Fig. 3 we performed UV/Vis and PL
experiments to examine the spectral changes of dendritic dye 15T5N upon the addition of ZnO
nano-rod and surface-modified nano-rods ZnO -PNH (with a weight ratio of 1:1 for both mixtures) in
X
organic solvent (DMF) and solid film. As shown in Figs. 3(b) and 3(d), the PL spectra of dendritic dye
15T5N exhibited an emission band at 557 nm in organic solvent, which was red-shifted to 600 nm in
the deposited solid film due to the occurrence of aggregation phenomenon. Upon the addition of ZnO
nano-rod and surface-modified nano-rod ZnO -PNH to dendritic dye 15T5N, the fluorescence
3
0
emissions of nano-rod mixture 15T5N/ZnO and supramolecular nano-composites 15T5N/ZnO -PNH
x
were all significantly quenched in organic solvent (DMF) as shown in Fig. 3(b). Likewise, the
emission intensities of dendritic dye 15T5N in solid films were significantly quenched but the
emission peak of 557 nm in DMF was red-shifted to 600-626 nm in solid films of nano-rod mixture
1
5T5N/ZnO and supramolecular nano-composites 15T5N/ZnO -PNH, but the PL emissions of
x
supramolecular nano-composites 15T5N/ZnO -PNH and 15T5N/ZnO -PNH with higher contents
3
0
10
of surfactant T-PNH were further quenched (with red-shifted emission peaks at 626 nm) in contrast to
stronger PL emissions (with emission peaks at 600 nm) of nano-rod mixture 15T5N/ZnO and
supramolecular nano-composite 15T5N/ZnO -PNH in Fig. 3(d), which might be due to the higher
100
electron transfer via supramolecular interactions in 15T5N/ZnO -PNH and 15T5N/ZnO -PNH
30
10
with higher contents of surfactant T-PNH. Similarly, the UV/Vis spectra of dendritic dye 15T5N
revealed the absorption bands with a broad range from 320-550 nm in DMF of Fig. 3(a), which were
further red-shifted to 320-700 nm in solid films of Fig. 3(c) owing to the stronger H-bonded
interactions of the diethylaminotriazinyl group on dendritic dye 15T5N and the H-bonded head (imide
1
5

ACCEPTED MANUSCRIPT
group) of surfactant T-PNH in solid films of supramolecular nano-composites 15T5N/ZnO -PNH
3
0
and 15T5N/ZnO -PNH. However, upon the addition of non-surface-modified ZnO nano-rods, due to
1
0
lacking of H-bonded interactions, nano-rod mixture 15T5N/ZnO in solid film did not illustrate clear
red-shifted absorption as those of H-bonded nano-composites 15T5N/ZnO -PNH and
3
0
1
5T5N/ZnO -PNH in Fig. 3(c). Therefore, such significant fluorescence quenching of both
10
supramolecular nano-composites 15T5N/ZnO -PNH and 15T5N/ZnO -PNH with higher contents
3
0
10
of surfactant T-PNH was attributed to the occurrence of electron transfer phenomena from 15T5N to
surface-modified nano-rods ZnO -PNH and ZnO -PNH via the H-bonded surfactant T-PNH.
30
10
However, the fluorescence quenching was saturated in supramolecular nano-composite
5T5N/ZnO -PNH, so 15T5N/ZnO -PNH was chosen for the later investigation of supramolecular
1
3
0
30
nano-composite. According to this result, our hypothesis to introduce a surfactant T-PNH via bridging
in between dendritic dye 15T5N and ZnO nano-rods which enabled the imide and thiol group bonding
with the terminal hydrogen of surfactant T-PNH successfully.
Furthermore, to validate the insights into the formation of triple H-bonds between the surfactant
T-PNH and dendritic dye 15T5N in our system. We performed comparison experiments by
introducing a counterpart surfactant T-PC6 (see Scheme 2) along with T-PNH and the corresponding
PL spectral changes of dendritic dye 15T5N, nano-rod mixture 15T5N/ZnO, supramolecular
nano-composites 15T5N/ZnO -PNH, and 15T5N/ZnO -PC6 are summarized in Fig. 4. Upon the
3
0
30
addition of ZnO nano-rods, the fluorescence intensity of dendritic dye 15T5N (at 600 nm) was
significantly quenched in Fig. 4. Moreover, in the presence of surfactants T-PNH and T-PC6, the
fluorescence intensities of supramolecular nano-composites 15T5N/ZnO -PNH and
3
0
1
5T5N/ZnO -PC6 were further quenched by surface-modified nano-rods ZnO -PNH and
3
0
3
0
ZnO -PC6 due to the formation of triple and double hydrogen-bonding between dendritic dye 15T5N
3
0
and surfactants T-PNH and T-PC6, respectively. However, in the presence of surfactant T-PC6 the
fluorescence intensity of supramolecular nano-composite 15T5N/ZnO -PC6 was less quenched in
30
1
6

ACCEPTED MANUSCRIPT
Fig. 4. Emission spectra of dendritic dye 15T5N, nano-rod mixture 15T5N/ZnO, supramolecular
nano-composites 15T5N/ZnO -PNH, and 15T5N/ZnO -PC6 in solid film. (λex = 350 nm)
3
0
30
contrast to supramolecular nano-composite 15T5N/ZnO -PNH. Therefore, due to the attachment of
3
0
soft alkyl chains (-C H ) to surfactant T-PC6 which hampered the H-bonded strength with dye
6
13
15T5N, the electron transfer phenomenon is less efficient than as observed in the presence of
surfactant T-PNH.
Furthermore, the hybrid ZnO nano-rods were directly investigated by TEM morphological
measurements to verify the dimensions of ZnO nano-rods and account for the contribution of
surfactant T-PNH for electron transfer from dendritic dye 15T5N to ZnO nano-rods. Fig. 5 (a) shows
that the non-modified ZnO nano-rods roughly possessing a length of 50 nm and a width of 10 nm were
aggregated to some extents. In Fig. 5 (b), dendritic dye 15T5N was uniformly widespread as grey color
in nano-rod mixture 15T5N/ZnO. As shown in Fig. 5 (c), a thin layer of dendritic dye 15T5N in
supramolecular nano-composite 15T5N/ZnO -PNH was formed in the peripheral part of
30
surface-modified nano-rod ZnO -PNH, which was mainly because dendritic dye 15T5N was
30
H-bonded with surface-modified nano-rod ZnO -PNH to enhance the miscibility of dendritic dye
3
0
1
7

ACCEPTED MANUSCRIPT
Fig. 5. TEM images: (a) ZnO nano-rods (b) nano-rod mixture 15T5N/ZnO (c) supramolecular
nano-composite 15T5N/ZnO -PNH. (scale bar = 50 nm)
3
0
1
5T5N with surface-modified nano-rod ZnO -PNH. In contrast to surfactant T-PNH, due to the
30
attachment of soft alkyl chains (-C H ) to surfactant T-PC6 which hampered the H-bonded strength
6
13
with dye 15T5N, the electron transfer phenomenon is less efficient in supramolecular nano-composite
5T5N/ZnO -PC6 than as observed in supramolecular nano-composite 15T5N/ZnO -PNH
1
3
0
30
containing surfactant T-PNH. Furthermore, the extents of H-bonds in both supramolecular
nano-composites 15T5N/ZnO -PC6 and 15T5N/ZnO -PNH were compared by significant changes
3
0
30
in the morphological photos TEM of Fig. S6 and Fig. 5 (c), respectively. In contrast to supramolecular
nano-composite 15T5N/ZnO -PC6, there is no thin layer of dendritic dye 15T5N formed in the
3
0
peripheral part of surface-modified nano-rod ZnO -PC6 in Fig. S6 due to weaker H-bonds in
30
supramolecular nano-composite 15T5N/ZnO -PC6. Accordingly, it is clear to verify the difference of
30
morphological photos caused by the formation of H-bonded effects.
Significant fluorescence quenching studies of dendritic dye 15T5N, nano-rod mixture
1
5T5N/ZnO, supramolecular nano-composites 15T5N/ZnO -PC6 and 15T5N/ZnO -PNH were
30 30
further proceeded by performing life time decay experiments. As shown in Fig. 6, fluorescence life
time decay patterns can be obtained by using time-correlated single-photon counting (TCSPC)
methodology. The excited state of supramolecular nano-composite 15T5N/ZnO -PNH had a reduced
3
0
half-life time of 0.425 ns in contrast to pure dendritic dye 15T5N (0.69 ns). This is quite consistent
1
8

ACCEPTED MANUSCRIPT
Fig. 6. Life time decay patterns (monitored at λ = 530 nm and λex = 375 nm) of dendritic dye 15T5N,
nano-rod mixture 15T5N/ZnO, supramolecular nano-composites 15T5N/ZnO -PC6 and
3
0
1
5T5N/ZnO -PNH in solid films.
30
Table 1. Time-correlated single-photon counting (TCSPC) photoluminescence quenching efficiency
PLQE), decay constant and quenching rate constant kcf values of 15T5N, 15T5N/ZnO,
5T5N/ZnO -PNH, and 15T5N/ZnO -PC6 (monitored at λ = 530 nm and λex = 375 nm).
(
1
X
30
1
9

ACCEPTED MANUSCRIPT
with the stronger PL quenching of supramolecular nano-composite 15T5N/ZnO -PNH observed in
3
0
Fig. 3(d) compared with dendritic dye 15T5N. The related TCSPC values of photoluminescence
quenching efficiency (PLQE) and quenching rate constant kcf of 15T5N, 15T5N/ZnO,
1
5T5N/ZnO -PNH (x = 10, 30, and 100), and 15T5N/ZnO -PC6 are demonstrated in Table 1.
X 30
Among all k values in Table 1, supramolecular nano-composite 15T5N/ZnO -PNH (solid-film)
cf
30
9
possessed the maximum quenching rate constant k = 5.7 x 10 /s, which is 17 times higher than that of
cf
8
nano-rod mixture 15T5N/ZnO (k = 3.3 x 10 /s) due to the H-bonded interaction of dendritic dye
cf
1
5T5N and surface-modified nano-rod ZnO -PNH to induce more efficient supramolecular electron
30
transfer. In contrast to supramolecular nano-composite 15T5N/ZnO -PNH, the lower quenching rate
30
9
constant k = 3.7 x 10 /s of 15T5N/ZnO -PNH was attributed to the over-supply and aggregation of
cf
10
surfactant T-PNH in surface-modified nano-rod ZnO -PNH (with a lower weight ratio of ZnO),
1
0
8
which was also verified in Fig. 2(b). Moreover, the lowest quenching rate constant k = 4.0 x 10 /s of
cf
1
5T5N/ZnO -PNH among all supramolecular nano-composites was observed due to the deficient
100
supply of surfactant T-PNH in surface-modified nano-rod ZnO -PNH. However, supramolecular
1
00
nano-composite 15T5N/ZnO -PNH still possessed a higher rate constant k than that of nano-rod
1
00
cf
8
mixture 15T5N/ZnO (k = 3.3 x 10 /s for nano-rods without any surface modification). Thus, it is
cf
apparent that the proper weight ratio of 30:1 for nano-rod ZnO to surfactant T-PNH improves the
electron transfer from dendritic dye 15T5N to surface-modified nano-rod ZnO -PNH to the highest
3
0
degree.
Furthermore, we performed FT-IR measurements to study H-bonded interactions of
surface-modified nano-rod ZnO -PHN, dendritic dye 15T5N, and supramolecular nano-composite
3
0
1
5T5N/ZnO -PNH as summarized in Fig. S7. Upon the addition of dendritic dye 15T5N to the
30
surface-modified nano-rod ZnO -PNH to form supramolecular nano-composite 15T5N/ZnO -PNH,
3
0
30
the N-H stretching band of dendritic dye 15T5N was broadened and the C=O stretching band of
-1
dendritic dye 15T5N was also shifted to a higher wavenumber 1637cm , which confirmed the
2
0

ACCEPTED MANUSCRIPT
formation of H-bonds via the diethylaminotriazinyl group of dendritic dye 15T5N and the H-bonded
head (imide group) of surface-modified nano-rod ZnO -PNH.
3
0
In order to verify the existence of H-bonds between dendritic dye 15T5N and surfactant T-PNH,
supramolecular nano-composite 15T5N/ZnO -PNH was further examined by variable temperature
30
FT-IR spectroscopy as illustrated in Figs. 7(a)-(d). Upon heating the samples up to 180 °C in Figs. 7(a)
-1
and 7(c), the corresponding C=O stretching band of surfactant T-PNH at 1637 cm and N-H stretching
-1
band of dendritic dye 15T5N at 3408 cm were both shifted to higher stretch wavenumbers of 1682
-1
and 3423 cm , respectively. However, as the samples cool down to 60 °C, the corresponding C=O
stretching band of surfactant T-PNH and N-H stretching band of dye 15T5N were restored to their
original wavenumbers in Figs. 7(b) and 7(d). According to this result, the occurrence of
hydrogen-bonds between dendritic dye 15T5N and surfactant T-PNH in Fig. 7 (e) is confirmed and
thus to facile electron transfer from dye 15T5N to ZnO via surfactant T-PNH.
2
1

ACCEPTED MANUSCRIPT
Fig. 7. (a)-(d) Variable FTIR spectra of supramolecular nano-composite 15T5N/ZnO -PNH of C=O
3
0
(a and b) and N-H (c and d) stretching band curve, (e) pictorial diagram of H-bonded structure in
nano-composite 15T5N/ZnO -PNH containing dendritic dye 15T5N and surface-modified nano-rod
3
0
ZnO -PNH.
3
0
2
2

ACCEPTED MANUSCRIPT
As shown in Fig. 8, the energy levels of electronic states for organic molecules generally
correspond to the energy carried by UV-visible radiation and thus to absorb energy by the
electromagnetic radiation and promote an electron from a lower energy molecular orbital (valence
band) to a higher energy molecular orbital (conduction band). For the efficient electron transfer to
occur from electron donor to acceptor, the lowest unoccupied molecular orbital (LUMO) level of
electron donor (i.e., 15T5N) should be above that of acceptor (i.e., ZnO nano-rods). However, the
highest occupied molecular orbital (HOMO) level of the hole donor should be below that of the
acceptor in order to transport the holes. In addition, the HOMO and LUMO levels of surfactant T-PNH
should fall in between those of both donor and acceptor as shown in Fig. 8, which can reduce energy
barriers in both transportation of electrons and holes. The similar approach of a surfactant with
intermediate HOMO and LUMO levels has also been developed in the literature [30].
Fig. 8. Energy level diagram of LUMO/HOMO levels for dendritic dye 15T5N, surfactant T-PNH,
and ZnO nano-rods.
2
3

ACCEPTED MANUSCRIPT
Normally, dealing with new materials the cyclic voltammetry (CV) is utilized to analyze energy
band structures, which contain the energy levels of HOMO, LUMO, and the bandgap between them.
Since the active electron-transfer moieties of dendritic dye 15T5N (electron donor) and surfactant
T-PNH are complimentary components of the H-bonded adduct as supramolecular nano-composite
1
5T5N/ZnO -PNH, the energy levels of dye 15T5N, surfactant T-PNH, and ZnO nano-rods are
30
compared for the possibility of electron transfer. The concerning results of cyclic voltammetry (CV)
measurements are demonstrated in Fig. S8.
As illustrated in Fig. 8 and Table S2, the energy band structures of HOMO and LUMO levels of
dendritic dye 15T5N, surfactant T-PNH, and ZnO nano-rods were obtained from the redox potentials
of Ered and E via CV measurements, which were measured according to the following empirical
ox
Bredas equation (i.e., ELUMO = EHOMO+E ). The sequential LUMO levels of dendritic dye 15T5N
g
(-3.31 eV), surfactant T-PNH (-3.75 eV), and ZnO nano-rods (-4.10 eV) suggested the plausible
mechanism of electron transfer from dye 15T5N to ZnO nano-rods.
The orbitals of dendritic dye 15T5N and surfactant T-PNH were calculated using a Hartree-Fock
algorithm to reveal the HOMO level on dendritic dye 15T5N, while the LUMO was centered on
surfactant T-PNH moiety (Fig. 9). The LUMO energy difference between dendritic dye 15T5N and
Fig. 9. Theoretical study of model compounds, i.e., dendritic dye 15T5N and surfactant T-PNH, for
supramolecular nano-composites 15T5N/ZnOx-PNH.
2
4

ACCEPTED MANUSCRIPT
surfactant T-PNH can be attributed to the change of the π conjugation after the formation of the
H-bonded adduct, which also weakened the imide moiety (C=O) conjugated to the perylene system in
surfactant T-PNH. Accordingly, the theoretical calculation further validated the plausible electron
transfer phenomena from dendritic dye 15T5N to ZnO nano-rods via surfactant T-PNH.
4. Conclusion
In conclusion, this study is aimed for synthesis of nano-composites with supramolecular (i.e.,
H-bonded) properties and investigation of electron transfer effects among supramolecular
nano-composites, where thiophene-based dendritic dye 15T5N containing
,4-bis(ethylamino)-1,3,5-triazine core acted as an electron donor. Moreover, ZnO nanorods were
2
surface-modified with two kinds of perylenebisimide (PBI)-based surfactants (T-PNH and T-PC6)
through the reaction of a thiol group at the termini of T-PNH and T-PC6 to form ZnOx-PNH and
ZnOx-PC6, respectively, which were synthesized to improve electron transport as an electron acceptor.
Finally, supramolecular nano-composites 15T5N/ZnOx-PNH were constructed by dendritic dye
1
5T5N and surface-modified nano-rods ZnOx-PNH. Based on TCSPC results, the supramolecular
nano-composite 15T5N/ZnO -PNH (solid-film) possessed the maximum quenching rate constant k
cf
3
0
9
8
=
5.7 x 10 /s, which is 17 times higher than that of nano-rod mixture 15T5N/ZnO (k = 3.3 x 10 /s)
cf
due to the H-bonded interaction of dendritic dye 15T5N and surface-modified nano-rod ZnO -PNH
3
0
to induce more efficient supramolecular electron transfer. Thus, it is apparent that surfactant T-PNH
improves the electron transfer from dendritic dye 15T5N to surface-modified nano-rod ZnO -PNH.
3
0
In contrast to surfactant T-PNH, less efficient electron transfer of surfactant T-PC6 was observed in
TCSPC and PL measurements because of the steric hindrance of long alkyl chains (-C H ) attached to
6
13
surfactant T-PC6, which hampered the H-bonded strength of surface-modified nano-rod ZnO -PC6
3
0
with dendritic dye 15T5N. Such stronger supramolecular interactions of surface-modified nano-rod
ZnO -PNH with dendritic dye 15T5N have been proven to be achieved due to the formation of triple
3
0
2
5

ACCEPTED MANUSCRIPT
H-bonds between dendritic dye 15T5N and surfactant T-PNH. Additionally, the theoretical
calculations were further validated the plausible electron transfer phenomena from dye 15T5N to ZnO
nano-rods via surfactant T-PNH. Finally, we expected that these supermolecular nano-composites will
have favorable electron transfer effect by means of the formation of H-bonded nano-composites,
which could lead to superior performance of photovoltaic cells and chemical sensors in the future
applications.
Acknowledgment
The financial supports of this project are provided by the Ministry of Science and Technology
(MOST)
in
Taiwan
through
MOST
103-2113-M-009-018-MY3
and
MOST
103-2221-E-009-215-MY3.
References
[
[
[
1] Mohammed OFA. Layer-by-Layer ZnO nanoparticle-PbS quantum dot-self-assembly platform
for ultrafast interfacial electron injection. Small 2015;11:112-8.
2] Samia ACS, Chen X, Burda C. Semiconductor quantum dots for photodynamic
therapy. J Am Chem Soc 2003;125:15736-7.
3] Xu H, Pang X, He Y, He M, Jung J, Xia H, Lin Z, et al. An unconventional route to
monodisperse and intimately contacted semiconducting organic–inorganic nanocomposites.
Angew Chem Int Ed 2015;54;4636-40.
[
[
4] Galoppini E, Rochford J, Chen H, Saraf G, Lu Y, Hagfeldt A, Boschloo G, et al. Fast electron
transport in metal organic vapor deposition grown dye-sensitized ZnO nanorod solar cells. J Phys
Chem B 2006;110:16159-61.
5] Zhang H, Cui Z, Wang Y, Zhang K, Ji X, Lu C, et al. From water-soluble CdTe nanocrystals to
fluorescent nanocrystal-polymer transparent composites using polymerizable surfactants. Adv
2
6

ACCEPTED MANUSCRIPT
Mater 2003;15:777-80.
[
[
[
6] EI Saeed AM, EI-Fattah MA, Azzam AM. Synthesis of ZnO nanoparticles and studying its
influence on the antimicrobial, anticorrosion and mechanical behavior of polyurethane composite
for surface coating. Dyes Pigm 2015;121:282-9.
7] Wei H, Sun H, Zhang H, Gao C, Yang B, et al. An effective method to prepare
polymer/nanocrystal composites with tunable emission over the whole visible light range. Nano
Res 2010;3:496-505.
8] Sun H, Zhang H, Zhang J, Wei H, Ju J, Li M, et al. White-light emission nanofibers obtained
from assembling aqueous single-colored CdTe NCs into a PPV precursor and PVA matrix. J
Mater Chem 2009;19:6740-4.
[
[
[
[
9] Lee C, Sundar VC, Heine JR, Bawendi MG, Jensen KF, et al. Full color emission from II-VI
semiconductor quantum dotepolymer composites. Adv Mater 2000;12:1102-5.
10] Chen L, Xu J, Holmes JD, Morris MA. A facile route to ZnO nanoparticle superlattices: Synthesis,
functionalization, and self-assembly. J Phys Chem C 2010;114:2003-11.
11] Pang L, Shen YM, Tetz K, Fainman Y. PMMA quantum dots composites
of pre-polymerization. Opt Express 2005;13:44-9.
fabricated via use
12] Lü C, Gao J, Fu Y, Du Y, Shi Y, Su Z, et al. A ligand exchange route to highly luminescent
surface-functionalized ZnS nanoparticles and their transparent polymer nanocomposites. Adv
Funct Mater 2008;18:3070-9.
[
[
13] Locklin J, Patton D, Deng S, Baba A, Millan M, Advincula RC, et al. Conjugated
oligothiophene-dendron-capped CdSe nanoparticles: Synthesis and energy transfer. Chem Mater
2
004;16:5187-93.
14] Gao J, Lü C, Lü X, Du Y. A Phen-functionalized nanoparticles/polymer fluorescent
nanocomposites via ligand exchange and in-situ bulk polymerization. J Mater Chem
2
007;17:4591-7.
2
7

ACCEPTED MANUSCRIPT
[
[
[
[
[
15] Althues H, Palkovits R, Rumplecker A, Simon P, Sigle W, Bredol M, et al. Synthesis and
characterization of transparent luminescent ZnS:Mn/PMMA nanocomposites. Chem Mater
2
006;18:1068-72.
16] Hung CH, Whang WT. Effect of surface stabilization of nanoparticles on luminescent
characteristics in ZnO/poly(hydroxyethyl methacrylate) nanohybrid films. J Mater Chem
2
005;15:267-74.
17] Kyaw AKK, Wang DH, Wynands D, Zhang J, Nguyen TQ, Bazan GC, et al. Improved light
harvesting and improved efficiency by insertion of an optical spacer (ZnO) in solution processed
small molecule solar cells. Nano Lett 2013;13:3796-801.
18] Yi M, Yi J, Wang J, Wang L, Gao W, Lin Y, Luo Q, Tan H, Ma CQ, Wang H, et al.
Perylenediimide derivatives based on a dendritic oligothiophene core as electron acceptor for
use in polymer solar cells. Dyes Pigm 2017;139:498-508.
19] Keshtov ML, Godovsky DY, Kuklin SA, Lee J, Kim J, Lim B, Lee HK, Biswas S, Koukaras
EN, Sharma GD, et al. Design, synthesis and photophysical properties of D1-A-D2-A-D1-type
small molecules based on fluorobenzotriazole acceptor and dithienosilole core donor for
solution processed organic solar cells. Dyes Pigm 2016;132:387-97.
[
[
[
20] Zhang W, Sun Y, Wei C, Lin Z, Li H, Zheng N, Li F, Yu G, et al. Vinylidenedithiophen-
methyleneoxindole-based donor-acceptor copolymers with 1D and 2D conjugated backbones:
Synthesis, characterization, and their photovoltaic properties. Dyes Pigm 2017;144:1-8.
21] Marczak R, Werner F, Gnichwitz JF, Hirsch A, Guldi DM, Peukert W, et al.
Communication
via electron and energy transfer between zinc oxide nanoparticles and organic adsorbates. J Phys
Chem C 2009;113:4669-78.
22] Zhou J, Zuo Y, Wan X, Long G, Zhang Q, Ni W, et al. Solution-processed and
high-performance organic solar cells using small molecules with a benzodithiophene unit. J Am
Chem Soc 2013;135:8484-7.
2
8