Nghiên cứu tổng hợp vật liệu bán dẫn hữu cơ ứng dụng trong lĩnh vực quang điện tử tt tiếng anh

MINISTRY OF EDUCATION
AND TRAINING

VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY

GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY
-----------------------------

PHAN DINH LONG

RESEARCH ON THE SYNTHESIS OF ORGANIC
SEMICONDUCTING METERIALS FOR OPTOELECTRONIC
APPLICATIONS

Major

: Organic Chemistry

Code

: 62.44.01.02

SUMMARY OF DOCTOR THESIS

Ha Noi -2019
1


The thesis was completed at Institute of Chemistry-Vietnam Academy of Science and
Technology.

Supervisors 1: Dr. Hoang Mai Ha
Supervisors 2: Assoc. Prof .Dr. Nguyen Phuong Hoai Nam

Reviewer 1: …
Reviewer 2: …
Reviewer 3: ….

This thesis will be defended at the doctoral thesis evaluation council at Graduate
University of Science and Technology - Vietnam Academy of Science and Technology
Time………... 2019

The thesis could be found at:
- National Library of Vietnam
- Library of Graduate University of Science and Technology
2


INTRODUCTION
1. Necessity of the thesis
Organic materials are gradually replacing inorganic materials in all areas of
science, technology and life. In the field of optics, electricity and electronics,
organic materials have showed many superior properties, such as: soft, light, easy to
manufacture on a large scale and relatively low cost. In particular, the research
direction of manufacturing organic optoelectronic devices such as organic light
emitting diodes (OLEDs), organic solar cells (OSCs), and organic field effect
transistors (OFET) have strongly developed in recent years. However, in
comparison with inorganic materials, organic semiconductors still exhibit major
disadvantages such as low carrier mobility, low power conversion efficiency and
low durability. Therefore, the study to overcome these disadvantages is an urgent

task to apply this material into practice.
In recent years, the optoelectronic industry has developed and made a great
contribution to the economy of Vietnam. Some researches on the fabrication of
OPV and OLED components have been done over last years. However, so far, there
are very few domestic research groups which can synthesize organic
semiconducting materials. In order to approach a new and potential research
direction, we choose the topic: "Research on synthesis of organic semiconducting
for optoelectronic applications".
2. Research objectives of the thesis
The thesis focus on the synthesis of new semiconducting polymers including
wide band-gap copolymers, low band-gap copolymers and terpolymers. The optical
properties, electrical properties, crystal structure and morphology of these polymers
were investigated. These polymers were applied to OFET and OPV fabrication.
3. Main research contents of the thesis
Overview of organic semiconducting materials and organic optoelectronic
devices.
Synthesis of copolymers based on diketopyrropyrole group (DPP6T-C4)
Synthesis of wide band-gap copolymers T-3MT and 2T-3MT
Synthesis of terpolymers 3MTB and 3MTT
Study on the optical properties, electrochemical properties, semiconducting
properties of polymers
Study of crystal structure and morphology of synthesized polymers
Fabrication of optoelectronic devices: Organic solar cells (OPV) and organic
field effect transistors (OFET).

1


Chapter 1. INTRODUCTION
1.1. π-Conjugated Organic Materials

The name organic semiconductor denotes a class of materials based on carbon that
display semiconducting properties, the common characteristics is that the electronic
structure is based on π-conjugated double bonds between carbon atoms. The
delocalization of the electrons in the π-molecular orbitals is the key feature, that
allows injection delocalization and charge transport. Semiconductivity may be
exhibited by single molecules, oligomers and polymers. Semiconducting small
molecules include the polycyclic compounds as pentacene, anthracene, rubrene,...
Polymeric organic semiconductors include poly(3-hexylthiophene), poly(pphenylene vinylene), polyacetylene, polyfluorenes
1.2. Some key reactions in the synthesis of conjugated structures
1.2.1. Suzuki coupling reaction
1.2.2. Stille coupling reaction
1.2.3. Heck coupling reaction
1.2.4. Sonogashira coupling reaction
1.3. Organic electronic devices
1.3.1. Charge Transport in Organic Semiconductors
The theory of charge transport in organic semiconductors has been reviewed
extensively, and many transport models have been proposed based on the welldocumented behavior of inorganic semiconductors. However, the exact mechanisms
of charge injection and transport are still seriously debated. The general
mechanisms that are pertinent to the design of new semiconducting materials are
outlined here, but for more detailed discussions, one may refer to the papers cited in
this section. In classical inorganic semiconductors such as silicon, atoms are held
together with strong covalent or ionic bonds forming a highly crystalline threedimensional solid. Therefore, strong interactions of the overlapping atomic orbitals
cause charge transport to occur in highly delocalized bands that are mainly limited
by defects, lattice vibrations, or phonon scattering in the solid. In contrast, organic
semiconductors are composed of individual molecules that are only weakly bound
together through van der Waals, hydrogen-bonding, and π-π interactions and
typically produce disordered, polycrystalline films. Charge delocalization can only
occur along the conjugated backbone of a single molecule or between the π-orbitals
of adjacent molecules. Therefore, charge transport in organic materials is thought to
rely on charge hopping from these localized states.

1.3.2. Organic field effect transistor (OFET)
The organic field effect transistor (Organic Field Effect Transistor-OFET)
was first made by A.Tsumara in 1986. Since then a lot of research has been done to
improve material quality and improve manufacturing methods of accessories. The
organic field effect transistor is of great interest because the semiconductor layer
can be created at low temperatures on a large and flexible area at low cost.
2


1.3.3. Organic photovoltaic cell (OPV)
The first organic solar cell was C.Engel of Eastman Kodak was successfully
built in 1986. The term photovoltaic is derived from a combination of words: light
(photo) and electricity (voltaic) in Greek. Solar cells are capable of converting light
into electricity. Compared to inorganic solar cells, organic solar cells have many
advantages such as: easier manufacturing technology; flexibility, transparency;
highly variable, highly flexible; light and low cost.
1.4. Overview of research situation on the synthesis of organic semiconductor
materials
1.4.1. Research situation in the world
1.4.1.1. Semiconducting polymers bearing only donor groups
Representative polymers developed for polymer-based solar cells are poly
(3-hexylthiophene) (P3HT), poly (1,4-phenylene-vinylene) (PPVs), and poly [2methoxy-5- (3,7-dimethyloctyloxy) -1,4-phenylene-vinylene] (MDMO-PPV) that
have been extensively studied.
1.4.1.2. Conjugated donor (D)/acceptor (A) copolymers
In other studies, one of the most effective methods to narrow the band gap
of a major polymer is to combine two types of monomers with different electronic
nature, one that is rich in electronics - called the donor parts (such as fluorene,
carbazole, dibenzosilole, benzodithiophene) and the other component is acceptor,
(such as benzodiathiazole and diketopyrrolopyrrole).
In recent years, many D-A conductive polymers have been synthesized and

used to fabricate electronic devicescomponents. Especially in the field of
application to manufacture PSC, according to published documents. The conversion
of photovoltaic energy into electricity has reached 10 to more than 12%. When there
is fluorine atoms in the molecular composition of polymers, the performance of
PSC components made from this polymer is improved in the direction of increasing.
After nearly 20 years of development, the tendency to synthesize conjugated
polymers for the manufacture of optoelectronic components from polymers only
carries the group for electronics to structural copolymers and terpolymers. The
synthesis of conjugated polymers aims to control the energy levels of HOMO and
LUMO, improve solubility, and control the structure so that polymers with crystals
are suitable for different applications.
1.4.1.3. Copolymers based on the Diketopyrrolopyrrople group (DPP)
Recently, diketopyrrolopyrrole (DPP) has been used extensively in the
synthesis of polymers for manufacturing field-effect transistor components (OFET)
and organic solar cells (OPV), as they have a strong electron affinity and
symmetrical heterocyclic structure creates a flat structure with very strong foreign
molecular interactions. The solubility of these polymers can be controlled by
changing the alkyl chain length at 2 N positions of the DPP group.

3


1.4.1.4. Wide ban-gap copolymers
Among the various types of polymer donors, donor−acceptor (D−A)-type
conjugated copolymers offer high performance in non-fullerene PSC devices.
However, the absorption spectra of many kinds of D−A type copolymers overlap
with those of non-fullerene acceptors because of the strong intramolecular charge
transfer (ICT) between the donating and accepting units in the polymer backbone.
The design and synthesis of wide-bandgap conjugated polymers is one strategy for
enhancing the light-harvesting absorption area. The combination of a non-fullerene

acceptor and wide bandgap polymer can produce relatively broad complementary
absorption behavior, which can improve the external quantum efficiency (EQE) of
the final PSC and thus also increase the short-circuit current.
1.4.1.5. Terpolymers
Over the past few years, random terpolymers bearing one donor and two different
acceptors (or one acceptor and two different donors) having conjugated polymer
backbones have emerged as promising materials with many advantages over
electron-donating binary copolymers owing to the ability to fine-tune the internal
morphology of the active layer, solubility, absorption range, energy levels, and
polymer chain orientation of the former in blend films. Therefore, highly efficient
nonfullerene PSCs can be realized by using specific terpolymer systems and simple
device fabrication processes.
1.4.1.6. Synthesis of acceptor
From 2000 to 2010, fullurene derivatives were used as an acceptors in PSC.
The integration of acceptors in recent years has been developed in the
following three directions:
Non-fullerene acceptors with wide band gap energy (Eg> 1.9 ev).
Non-fullerene acceptors with medium forbidden region energy (1.9 eV> Eg >
1.5 ev ).
Non-fullerene acceptors with narrow-level region energy (Eg< 1.5 eV).
1.4.2. Domestic research situation
Overview the published literatures, nowadays, domestic studies have very
little research on the synthesis of conductiing polymer, mainly focusing on the
fabriction of of opto electronic devices.
The research team of Pham Hong Quang, University of Natural Sciences is
also working on making solar cells but based on CIGS thin film structure.
Meanwhile, the synthesis of semiconducting polymers in Vietnam is still in
its infancy. Beside the research group of Hoang Mai Ha at the Institute of
Chemistry, only the research group of Nguyen Tran Ha at National University of Ho
Chi Minh City has synthesized some polymers with conjugate structure and the first

step has been made organic solar cells using these polymers.

4


CHAPTER 2. EXPERIMENT
2.1. Chemicals and equipment
2.1.1. Chemicals and solvents
All chemicals used to synthesize copolymers and receiver elements used in
this study were purchased from Tokyo Chemical Industry Co., Ltd. (TCI), SigmaAldrich and ACROS Co.
2.1.2. Instrumentation
The molecular weights of the polymers were determined by gel permeation
chromatography (GPC, Agilent 1200 series GPC system) with o-dichlorobenzene
(ODCB) as the eluent (T58088C) on an Agilent GPC 1200 series instrument,
relative to a polystyrene standard. C, H, N, and S elemental analysis was performed
on an EA1112 (Thermo Electron Corp., West Chester, PA, USA) elemental
analyzer. The absorption spectra of the polymers as thin films and solutions
(chloroform, conc. 1 × 10−5 mol L−1) were obtained using a UV-vis absorption
spectrometer (Agilent 8453, photodiode array-type). The oxidation potentials of the
two copolymers were measured using cyclic voltammetry (Model: EA161 eDAQ).
The employed electrolyte solution contained 0.10 M tetrabutylammonium
hexafluorophosphate (Bu4NPF6) in acetonitrile. Ag/AgCl and Pt wire (0.5 mm in
diameter) electrodes were used as the reference and counter electrodes, respectively
(scan rate = 20 mV s−1).
Grazing incidence X-ray diffraction (GI-XRD) measurements were carried out at
the 3C (SAXS I) beamlines (energy = 11.040 keV, pixel size = 79.6 μm, wavelength
= 1.126 Å, 2 = 0°–20°) at the Pohang Accelerator Laboratory, Korea. The
parameters qxy and qz represent the components of the scattering vectors parallel and
perpendicular to the film surface, respectively. Atomic force microscopy (AFM,
Advanced Scanning Probe Microscope, XE-100, PSIA, tapping mode with a silicon

cantilever) was used to characterize the surface topographies of the thin-film
samples.
2.2. Synthesis of polymers
2.2.1. Synthetic scheme

5


Catalyst + Monomer + Solvent

Polymerization

Precipitation

Soxhlet extraction

Filter & dry

Scheme 2.1. Synthetic scheme of conjugated polymers
2.2.2. Synthesis of narrow-band gap polymer based on diketopyrrolopyrrole
group (P (DPP6T-C4))

7

10

P(DPP6T)-C4

Svheme 2.2. Synthesis of P(DPP6T-C4)
3,6-bis (5'-bromo-2,2'-bithiophen-5-yl) -2,5-bis (5-decylheptadecyl) pyrrolo

[3,4-c] pyrrole-1,4 (2H, 5H ) -dione (7) (275.9mg, 0.2mmol) and 5,5'-bis
(trimethylstannyl) -2,2'-bithiophene (10) (98.8mg, 0.2mmol) are dissolved in 20mL
toluene in the 3-neck flask. The solution is stirred with a magnetic stirrer in an
argon inert atmosphere. After 10 minutes, tetrakis (triphenylphosphine) palladium
(0) Pd(PPh3)4 (23mg, 10mol%) is added to the reaction mixture. The reaction
mixture is stirred in argon medium at 90° C for 6 hours. Then, the mixture is cooled
to room temperature, 60mL is added to the reaction mixture and the mixture is
6


stirred for another 10 minutes to precipitate the polymer. The precipitated polymer
is filtered and purified by Soxhlet extraction method with acetone, tetrahydrofuran
(THF), and chloroform to collect the insoluble polymer. Next, this polymer part is
dissolved in hot 1.2-diclorobenzene solvent. Insoluble particles in 1,2-diclorobenzen
are filtered out. The polymer solution is then concentrated and precipitated by
methanol to obtain 153 mg of dark green products, fusion efficiency of 54%.
Determination of structure of P(DPP6T-C4)
1H-NMR spectrum of this polymer has only 1 characteristic peak for
conjugated heterocyclic at δ 7.04ppm-7.09ppm. Typical peaks for the 5decylheptadecyl group are shown relatively clearly on 1H and 13C-NMR spectra.
Anal. Calcd. for (C86H128N2O2S6)n, Found: C, 73.22%; H, 9.04%; N,
1.97%; O, 2.32% and S, 13.45%.
Gel chromatography method is used for mass determination of polymer: Mn =
13292; Mw = 37801; PDI = 2,844.
2.2.3. Synthesis of wide band gap copolymers T-3MT and 2T-3MT
2.2.3.1. Synthesis of T-3MT

Scheme 2.3. Synthesis of T-3MT
Pd2(dba)3(0) (9.2 mg, 10.0 μmol) and P(o-tolyl)3 (12.2 mg, 40.0 μmol)
were added to a solution of compound 18 (0.247 g, 0.2 mmol) and compound 24
(0.06 g, 0.2 mmol) in toluene:DMF (9:1 v/v, 20 mL) at room temperature under

Ar atmosphere and the reaction mixture was allowed to stir at 100 °C for 24 h.
The cooled reaction mixture was poured into methanol (200 mL) to precipitate the
copolymer. The precipitated polymer was purified by Soxhlet extraction with
methanol, acetone, and chloroform, successively. After reducing the volume of
chloroform fraction in vacuo, the copolymer was then precipitated in methanol.
The final product was obtained in 83% yield
Determination of structure of T-3MT
1
H-NMR (500 MHz, CDC13):(ppm) 7,90 (s, 1H); 7.52 (s, 1H); 7,49 (s, 2H), 7,35
(s, 1H);7,18 (d, 8H); 7,11 (d, 8H);3,84 (s, 3H); 2,56(t, 8H);1,52-1,59 (m, 8H); 1,281,33 (m, 24H);0,86(t, 12H).
13
C NMR (125MHz, CDCl3): (ppm) 163,26; 141,89; 140,02; 128,57; 128,05;
35,61; 31,71; 31,25; 29,18; 22,59; 14,07
Anal. Calcd. for (C70H76O2S3)n: C, 80.41; H, 7.33; S, 9.20. Found: C,
80.23; H, 7.41; S, 9.18.
7


Gel chromatography method to determine the mass of polymer: Mn=
33,2kDa, PDI = 2.01.
2.2.3.2. Synthesis 2T-3MT

Scheme 2.4. Synthesis of 2T-3MT
Pd2(dba)3(0) (9.2 mg, 10.0 μmol) and P(o-tolyl)3 (12.2 mg, 40.0 μmol)
were added to a solution of compound 23 (0.269 g, 0.2 mmol) and compound 24
(0.06 g, 0.2 mmol) in toluene:DMF (9:1 v/v, 20 mL) at room temperature under Ar
atmosphere and the reaction mixture was allowed to stir at 100 °C for 24 h. The
cooled reaction mixture was poured into methanol (200 mL) to precipitate the
copolymer. The precipitated polymer was purified by Soxhlet extraction with
methanol, acetone, and chloroform, successively. After reducing the volume of

chloroform fraction in vacuo, the copolymer was then precipitated in methanol. The
final product was obtained in 88% yield
Determination of structure of 2T-3MT
1
H-NMR(500MHz, CDC13): (ppm)7,91 (s, 1H); 7.52 (s, 1H); 7,50 (s, 2H),
7,36 (s, 1H); 7,18 (d, 8H); 7,10 (d, 8H); 3,83 (s, 3H); 2,56(t, 8H);1,54-1,59 (8H);
1,26-1,34 (m, 24H);0,86(t, 12H).
13
C NMR (125 MHz, CDCl3): (ppm) 163,32; 141,96; 139,99; 128,57;
128,04; 35,61; 31,72; 31,25; 29,19; 22,60; 14,08
Anal. Calcd. for (C74H76O2S5)n: C, 76.77; H, 6.62; S, 13.85. Found: C,
76.51; H, 6.67; S, 13.78.
Gel chromatography method to determine the mass of polymer: Mn =
26,7kDa, PDI = 2,21
2.2.4. Synthesis of terpolyme 3MTB and 3MTT
2.2.4.1. Synthesis of 3MTB

Scheme 2.5. Synthesis of 3MTB
8


Monomer 29 (181 mg, 0.2 mmol), monomer 24 (11.7 mg, 0.04 mmol), and
monomer 30 (47.7 mg, 0.16 mmol) were dissolved into dried toluene (10 mL) and
dimethylformamide (DMF; 1 mL) and the solution was then degassed by bubbling
with nitrogen for 10 min. Subsequently, the catalyst (Pd2(dba)3(0); 9.2 mg, 10.0
μmol) and P(o-tolyl)3 (12.2 mg, 40.0 μmol) were added to the solution and the
reaction mixture was stirred at 100 oC for 24 h. The solution was cooled to room
temperature and poured into 300 mL of methanol to obtain the precipitated polymer.
The crude product was purified by successive Soxhlet extraction with acetone,
hexane, and chloroform. The chloroform fraction was concentrated to the minimum

volume and the solution was then precipitated in methanol, filtered, and dried to
yield the target 3MTB terpolymer. The final product was obtained in 89%
Determination of structure of 3MTB
1
H-NMR (500MHz, CDC13): (ppm) 8,02; 7,56-7,67; 7,26-7,34; 6,93;
3,84; 2,90-2,98;1,44-1,55; 0,98.
13
C NMR (125MHz, CDCl3): (ppm) 163,56; 162,90; 137,30; 132,88;
128,04; 124,36; 41,49; 34,38; 32,74; 28,97; 25,86; 23,18; 23,07; 14,28; 10,98.
Elemental Anal. Calcd for (C67H44O2S5)0.8(C40H42N2S5)0.2: C, 67.11; H, 6.13; N,
0.79; S, 22.40. Found: C, 67.02; H, 6.18; N, 0.81; S, 22.35.
Gel chromatography method to determine the mass of polymer: Mn=17.1
kDa, PDI = 2.46.
2.2.4.2. Synthesis of 3MTT

Scheme 2.6. Synthesis of 3MTT
Monomer 29 (181 mg, 0.2 mmol), monomer 24 (27.4 mg, 0.04 mmol), and
monomer 31 (47.7 mg, 0.16 mmol) were dissolved in dried toluene (10 mL) and
DMF (1 mL) and the solution was degassed by bubbling with nitrogen for 10 min.
Subsequently, the catalyst (Pd2(dba)3(0); 9.2 mg, 10.0 μmol) and P(o-tolyl)3 (12.2
mg, 40.0 μmol) were added to the solution and the reaction mixture was stirred at
100 oC for 24 h. The solution was cooled to room temperature and poured into 300
mL of methanol to obtain the precipitated polymer. The crude product was purified
by Soxhlet extraction with acetone, hexane, and chloroform, successively. The
chloroform fraction was evaporated properly and the polymer solution was then
precipitated in methanol, filtered, and dried to give the target 3MTT terpolymer.
The final product was obtained with 83% yield (Mn = 12.1 kDa, PDI = 3.07).
Elemental Anal. Calcd for (C67H44O2S5)0.8(C62H74N2O4S6)0.2: C, 67.09; H,
6.30; N, 0.51; S, 21.37. Found: C, 66.97; H, 6.34; N, 0.53; S, 21.26.
9

Determination of structure of 3MTT
1
H-NMR (500MHz, CDC13): (ppm)8,02; 7,65-7,72; 7,26-7,35; 6,93;
3,81; 2,90-2,96; 1,73-1,79;1,43-1,53; 0,97-1,04.
13
C NMR (125MHz, CDCl3): (ppm) 154,63; 137,24; 41,50; 34,47; 32,78;
29,00; 25,75; 23,35; 23,15; 14,13; 10,96.
Elemental Anal. Calcd for (C67H44O2S5)0.8(C62H74N2O4S6)0.2: C, 67.09; H, 6.30; N,
0.51; S, 21.37. Found: C, 66.97; H, 6.34; N, 0.53; S, 21.26.
Gel chromatography method to determine the mass of polymer: Mn=17.1
kDa, PDI = 2.46.
2.3. Organic thin film transistors (OTFT) Fabrication
To study charge transport properties of the synthesized polymers, BGTC TFT
device structure were employed. The gate electrode was n-type doped 〈100〉 silicon
wafer and the SiO2 gate insulator has a thickness of 300 nm. The substrate was
cleaned with acetone, cleaning agent, deionized water, and isopropanol in an
ultrasonic bath. The cleaned substrates were dried under vacuum at 120 oC for 1 h,
and then treated with UV/ozone for 20 min. Then, the wafers were immersed in a 8
mmol/L solution of n-octyltrichlorosilane (OTS) in anhydrous toluene for 30 min to
generate an hydrophobic insulator surface. The polymer layer was deposited on the
OTS-treated substrates by spin-coating polymer solutions (4 mg mL-1) at 1500 rpm
for 40 s. For annealing the TFTs, the samples were further placed on a hotplate in
air at 180oC for 10 min. Finally, the source and drain electrodes were prepared using
thermal evaporation of gold (100 nm) through a shadow mask with a channel width
of 1500 µm and a channel length of 100 µm. Field-effect current-voltage
characteristics of the devices were determined in air using a Keithley 4200 SCS
semiconductor parameter analyzer. The field-effect mobility upon saturation (µ) is
calculated from the equation: IDS = (W/2L)Ciµ(VG - VTH)2, where W/L is the channel

width/length, Ci is the gate insulator capacitance per unit area, and VG and VTH are
the gate voltage and threshold voltage, respectively.
2.4. Fabrication of polymer solar cells
Bulk heterojunction (BHJ) PSCs were fabricated with an inverted device
configuration (indium-tin-oxide (ITO)/ZnO/polymer:ITIC nm)/MoO3/ Ag). A thin
layer of ZnO was fabricated on the surface of ITO-patterned glass, which was
treated with UV-ozone for 20 min. After thermally annealing the ZnO layer at 160
°C for 1 h, the active layer was prepared on top of the ZnO layer by spin-coating
polymer:ITIC blend solutions with various ratios, dissolved in chlorobenzene.
Subsequently, the electrodes were deposited on the active layers by thermal
evaporation to form a 10 nm MoO3 layer and 100 nm Ag layer (0.04 cm2
photoactive area). A Keithley 2400 source meter was used to investigate the current
density–voltage (J–V) characteristics in the dark and under AM 1.5 G illumination
at 100 mW cm-2, as supplied by a solar simulator (Oriel, 1000 W). An AM 1.5 filter
(Oriel) and a neutral density filter were employed to adjust the light intensity. The
incident light intensity was measured with a calibrated broadband optical power
meter (Spectra Physics, Model 404). The external quantum efficiency (EQE)
10


spectral response was measured using a tungsten halogen light source combined
with a monochromator (Spectra Pro 2300, Acton Research).
CHAPTER 3. RESULTS AND DISCUSSION
3.1. Results of synthesis of polymers
3.1.1. Results of synthesis of polymer DPP6T-C4
The results of the elemental analysis show that the P synthesis reaction
(DPP6T-C4) obtains a high purity product with yield of 54%.
The method of determining molecular weight by gel permeation
chromatography shows that the polymer P (DPP6T-C4) has Mn = 13292; Mw =
37801; PDI = 2,844. Thus, the product is a polymer with a relatively large

molecular weight and a small distribution.
3.1.2. Results of synthesis of polymer T-3MT, 2T-3MT
The synthesized T-3MT and 2T-3MT exhibited good solubility in
tetrahydrofuran (THF), chloroform, and monochlorobenzene. The number-average
molecular weights (Mns) and polydispersity indices (PDIs) of T-3MT and 2T-3MT
were measured using gel permeation chromatography (GPC) with odichlorobenzene as the eluent at 80 °C. The resulting Mns and PDIs were 33.2 kDa
and 2.01 for T-3MT and 26.7 kDa and 2.21 for 2T-3MT, respectively.
3.1.3. Results of synthesis of polyme 3MTB and 3MTT
The synthesized 3MTB and 3MTT exhibited good solubility in THF, chloroform,
and monochlorobenzene. The number-average molecular weights (Mns) and
polydispersity indices (PDIs) of 3MTB and 3MTT were measured using gel
permeation chromatography (GPC) with o-dichlorobenzene as the eluent at 80 °C.
The resulting Mns and PDIs of 3MTB and 3MTT were 17.1 kDa and 2.46 for 3MTB
and 12.1 kDa and 3.07 for 3MTT, respectively.
3.2. Characterization of synthesized polymers
3.2.1. Physical properties and characteristics of optoelectronic devices of P
(DPP6T) -C4
3.2.1.1. Optical properties of P (DPP6T) -C4 and P(DPP6T) -C4/PC71BM blend
UV-Vis absorption spectra of P(DPP6T)-C4 and P(DPP6T) -C4/PC71BM
(1/2) combination in solution form and thin film on quartz substrate are shown in
Figure 3.2. Polymer P(DPP6T)-C4 has a weak absorption band at 400nm-550nm
and a strong absorption band in the range of 600nm-800nm.

11


1.0

(a)

(i)
(ii)

Absorbance (a.u.)

0.8

0.6

0.4

0.2

0.0
400

600

800

1000

Wavelength (nm)
1.4

(b)

(i)
(ii)

Absorbance (a.u.)

1.2
1.0
0.8
0.6
0.4
0.2
0.0
400

600

800

1000

Wavelength (nm)

Figure 3.6. UV-Vis absorption spectrum of P(DPP6T) -C4 (a) and P(DPP6T) C4/PC71BM combination (1/2) (b) in solution form (i) and thin film (ii)
3.2.1.2. Electrochemical properties of polymer P(DPP6T) -C4
Electrochemical properties of polymer P(DPP6T) -C4 in the film shows that
this polymer has an energy level of HOMO = -5.10 eV. Combined with the energy
width value of the forbidden region of the polymer film Eg = 1.47 eV obtained from
the UV-Vis absorption spectrum, we calculated the energy level LUMO = -3.63 eV.
These energy levels are suitable for making OPV components.
3.2.1.3. Crystal structure of P(DPP6T) -C4
The structure of P(DPP6T)-C4 is studied by GI-XRD diffraction in membrane
form (Figure 3.8). The out-of-plane diagram of this polymer membrane shows
intense diffraction peaks, indicating that the polymers have arranged themselves in

order to be perpendicular to the base. After the polymer film is incubated at 120°C,
the intensity of the diffraction peaks strongly indicates that the crystallinity of the
polymer film increases after annealing. This phenomenon explains the load mobility
of polymer increase after annealing.

12


105

2.0

(c)

(a)
10
Intensity

qz (Å-1)

1.5

1.0

P(DPP6T)-C4 (RT)
P(DPP6T)-C4 (120oC)

4

103

0.5
102

-1.5

-1

-0.5

0

0.5

1

1.5

2

4

6

8

qxy (Å-1)

10

12

14

16

18

20

2 (deg)

2.0

P(DPP6T)-C4 (RT)

(d)

(b)

P(DPP6T)-C4 (120oC)

Intensity

qz (Å-1)

1.5

1.0

102

0.5

-1.5

-1

-0.5

0

0.5

1

1.5

2

qxy (Å-1)

4

6

8

10

12

14

16

18

2 (deg)

Figure 3.8. X-ray diffraction scheme of P (DPP6T) -C4 in membrane form:
Schematic of 2-dimensional X-ray diffraction at normal temperature (RT) (a) and at
120oC (b), diagram of 1-dimensional X-ray diffraction out-of-plane (c) and in-plane
(d) at ambient temperature and at 120oC
3.2.1.4. Semiconductor properties P(DPP6T) -C4
In order to investigate the charge transport of the P(DPP6T)-C4 copolymers,
BGTC TFT devices were fabricated via the spin-coating method. The output
characteristics showed very good saturation behavior and clear saturation currents
that were quadratic to the gate bias. The carrier mobility (µ) was calculated by using
the saturation region transistor equation, IDS = (W/2L)µ C0 (VG-Vt)2, where IDS is the
source-drain current, VG the gate voltage, C0 the capacitance per unit area of the
dielectric layer, and Vt the threshold voltage. The TFTs fabricated with the
P(DPP6T)-C4 exhibited carrier mobilities of 0.57 cm2 V-1 s-1 with pristine film and
1.88 cm2 V-1 s-1 with annealed films, respectively, with a high current on/off ratio
(>106) and low threshold voltage.
3.2.1.5. P-n multi-layer structure OPV device based on P (DPP6T)-C4/PC71BM
The structure of OPV device was: ITO/PEDOT: PSS (40nm)/P (DPP6T) C4 (60nm)/PC71BM (30nm)/LiF (0.8 nm)/Al (100nm). Typically, p-n layers are
only fabricated by evaporation in vacuum using single molecules. In this study,
because P (DPP6T) -C4 is not soluble in chloroform solvent while PC71BM is well
soluble in chloroform, we can make p-n layers by conventional spin-coating method

13


(a)

Normalized Absorbance (a. u.)

3.1.6. BHJ-OPV device made from P (DPP6T-C4) and PC71BM
The BHJ-OPV device was made using P (DPP6T) -C4 as a donor and
PC71BM as an acceptor (Figure 3.7a). The structure of OPV components is:
ITO/PEDOT: PSS (40nm)/P combination (DPP6T) -C4: PC71BM (80nm)/LiF
(0.8nm)/Al (100nm). The combination of P (DPP6T) -C4 and PC71BM is dissolved
in 1,2-diclorobenzene solvent and the solution is spin-coating on the PEDOT layer:
PSS.
3.2.2. Physical properties and characteristics of optoelectronic devices of T3MT and 2T-3MT
3.2.2.1. Optical properties
The UV-vis absorption spectra of the two copolymers in the solution and thin film
states are shown in Figures 3.12. The maximum absorption wavelengths in the
solution states and films were respectively 523 and 520 nm for T-3MT and 529 and
519 nm for 2T-3MT. The spectra of both polymers were featureless with no wellresolved vibronic bands and strong absorption spectral bands from 400 to 600 nm
due to intramolecular charge transfer (ICT) between 3MT (the accepting unit) and
IDT/IDTT (the donating unit). Although the two polymers had different donating
units, their absorption maxima and spectral profiles were quite similar.
.
1.2

T-3MT
2T-3MT

0.9

0.6

0.3

0.0
300

400

500

600

700

Wavelength (nm)

Normalized Absorbance (a.u.)

1.2

(b)

T-3MT
2T-3MT

0.9

0.6

0.3

0.0
300

400

500

600

700

Wavelength (nm)

Figure 3.12. UV-vis absorption spectra of T-3MT and 2T-3MT in solution [solvent:
chloroform] (a) and thin film state (b).
3.2.2.2. Electrochemical properties of T-3MT and 2T-3MT

14


T-3MT
2T-3MT

0.003

(a)
Current (a. u.)

0.002
0.001
0.000
-0.001
-0.002
-0.003

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

E (V) vs Ag/AgCl

-5.32

-5.87

-4.30

PC71BM

-5.4

ITIC

-4.17 -4.14

IM-IDT

2T-3MT

Energy levels (eV)

T-3MT

-3.33 -3.27

(b)

-5.72
-6,10

Figure 3.16. Cyclic voltammograms of thin films of T-3MT and 2T-3MT
on Pt electrode (a). Energy diagrams of T-3MT and 2T-3MT as p-type copolymers
and IM-IDT, ITIC, and PC71BM as n-type small molecules (b).
Cyclic voltammetry (CV) was employed to determine the energy levels of the two
synthesized polymers, and the corresponding parameters are displayed in Figure
3.16. The HOMO energy was estimated from the onset oxidation potential of the
CV curve. The HOMO level (-5.32 eV) of 2T-3MT was slightly higher than that of

T-3MT (-5.40 eV), which might be due to the relatively stronger donor ability of
IDTT. The lowest unoccupied molecular orbital (LUMO) energy calculated from
the HOMO and optical bandgap was -3.33 eV for T-3MT and -3.27 eV for 2T3MT. As shown in Figure 3.16b, both polymers had a sufficient energy level offset
for use as p-type semiconductors with the three acceptors.
3.2.2.3. Crystalline structure of T-3MT, 2T-3MT and their blend with different
acceptor
Grazing incidence wide-angle X-ray diffraction (GIWAXD) measurements
were conducted for the wide-bandgap copolymers and the polymer:acceptor blend
films to better understand the performance of the PSC devices (Figure 3.17 and
3.18). The profiles of the as-cast films of the two polymers in the out–of–plane and
15


in–plane modes did not show clear crystalline behavior. The diffraction profiles of
the polymer:IM-IDT blend films displayed multiple ring patterns along all radial
directions, which is attributed to the crystalline nature of the IM-IDT acceptors.
Correspondingly, a bright diffraction spot was observed along the qz axis,
corresponding to the (010) diffraction of the polymer chains in the out–of–plane
profile. This observation indicates that the polymer chains of T-3MT and 2T-3MT
were arranged in a face-on orientation on the substrate, which might be driven by
crystallization of the IM-IDT acceptors. On the other hand, the blend films of two
polymers and ITIC did not show clear diffraction pattern, implying much less
crystalline morphology than that of IM-IDT based blend film. The polymer:PC71BM
blend films showed typical diffraction ring pattern of PC71BMs or its cluster along
all radial directions. The polymer donors did not show any crystalline character.
From these results, it was found that the polymer blends with ITIC or PC71BM are
much less crystalline compared to those with IM-IDT, which may explain the lower
Jsc and FF. In addition, the enhanced Jsc for the PSC employing the polymer and
IM-IDT can be ascribed to the predominant face-on orientation of the polymer
chains, which might facilitate charge transport via intermolecular hopping in the

vertical direction.

1

0
0

Out-of-plane

0.5

1

1.0

Out-of-plane

0.5

1

1.0

1.5

0.5

2.0

1.0

1.5

q (Å2-1)

1

0

0

Out-of-plane

0.5

1

Intensity (a.u.)

2

Intensity (a.u.)

1.0

1.5

In-plane

0.5

2.0

q

qxy (Å-1)

1.0

1.5

2

q(xy)
(Å-1)

q (Å-1)

Intensity (a.u.)

2

1

Intensity (a.u.)

qz (Å-1)

1.5

In-plane

qq(xy)
(Å-1)

qxy (Å-1)

qz (Å-1)

1.0

q2 (Å-1)
Intensity (a.u.)

Intensity (a.u.)

qz (Å-1)

1

0

(d)

0.5

2.0

2

0

(c)

1.5

In-plane

q(xy)
q
(Å-1)

qxy (Å-1)

(b)

Intensity (a.u.)

2

Intensity (a.u.)

qz (Å-1)

(a)

Out-of-plane

In-plane

0
0

1

0.5

1.0

qxy (Å-1)

1.5

q(xy)
q
(Å-1)

2.0

0.5

1.0

q2 (Å-1)

1.5

,
Figure 3.17. 2D GIWAXD patterns of the as-cast films of (a) T-3MT, (b) T3MT:IM-IDT, (c) T-3MT:ITIC, (d) T-3MT:PC71BM
16

1

0
0

Out-of-plane

0.5

1

1.0

Out-of-plane

0.5

1

1.0

1.5

0.5

2.0

1.0

1.5

q2 (Å-1)

1

0
0

Out-of-plane

0.5

1

Intensity (a.u.)

2

Intensity (a.u.)

1.0

1.5

In-plane

0.5

2.0

1.0

1.5

q2 (Å-1)

q(xy)
q
(Å-1)

qxy (Å-1)
Intensity (a.u.)

2

1

0
0

1

Intensity (a.u.)

qz (Å-1)

1.5

In-plane

q(xy)
q
(Å-1)

qxy (Å-1)

qz (Å-1)

1.0

q2 (Å-1)

Intensity (a.u.)

Intensity (a.u.)

qz (Å-1)

1

0

(d)

0.5

2.0

2

0

(c)

1.5

In-plane

q(xy)
q
(Å-1)

qxy (Å-1)

(b)

Intensity (a.u.)

2

Intensity (a.u.)

qz (Å-1)

(a)

Out-of-plane

0.5

1.0

1.5

q(xy)
q
(Å-1)

qxy (Å-1)

2.0

In-plane

0.5

1.0

1.5

q2 (Å-1)

Figure 3.18. 2D GIWAXD patterns of the as-cast films of (a) 2T-3MT, (bf) 2T3MT:IM-IDT, (c) 2T-3MT:ITIC, and (d) 2T-3MT:PC71BM.
Cấu trúc tinh thể của T-3MT, 2T-3MT và của các tổ hợp của polyme:
3.2.2.4. Morphological studies of the blend films
The surface topography of the as-cast active layer with no solvent additive
was evaluated by atomic force microscopy (AFM).
3.2.2.5. Non-fullerene polymer solar cells

To investigate the performance of non-fullerene PSCs based on the two
polymers used in this study, inverted BHJ PSCs were fabricated with the
ITO/ZnO/polymer:n-type small molecule/MoO3/Ag configuration.35 Two kinds of
non-fullerene small molecules (IM-IDT and ITIC) and PC71BM as a fullerene
derivative were selected for evaluation of the optimized device performance in
BHJ-type PSCs. Simple device fabrication was achieved by using a solventadditive-free as-cast blend film of the polymers and acceptors in different blend
ratios. Among the three kinds of PSCs, the polymer:IM-IDT blends showed higher
17


PCE values than the polymer:ITIC blend, and the best PCE of 3.96% was obtained
with the 2T-3MT:IM-IDT(1:1 wt. ratio)-based PSC.
3

(b)

T-3MT:IM-IDT(1:1)
T-3MT:ITIC(1:2)
T-3MT:PC71BM(1:1)

0

2

-3

-6

-9
-0.2

0.0

0.2

0.4

0.6

2T-3MT:IM-IDT(1:1)
2T-3MT:ITIC(1:1.5)
2T-3MT:PC71BM(1:2)

2

Current density (mA/cm )

2

Current density (mA/cm )

(a)

0.8

1.0

0
-2
-4

-6
-8
-0.2

1.2

0.0

Voltage (V)

(c)

(d)

60

T-3MT:IM-IDT (1:1)
T-3MT:ITIC (1:2)
T-3MT:PC71BM (1:1)

0.8

1.0

1.2

40

EQE (%)

EQE (%)

0.6

2T-3MT:IM-IDT (1:1)
2T-3MT:ITIC (1:1.5)
2T-3MT:PC71BM (1:2)

50

40
30
20

30
20
10

10
0

0.4

Voltage (V)

60
50

0.2

400

500

600

700

0

800

400

500

600

700

800

Wavelength (nm)

Wavelength (nm)

Figure 3.20- 3.21. J-V curves (a, b) and EQE spectra (c, d) of PSCs employing the
as-cast blend films of T-3MT and 2T-3MT with IM-IDT, ITIC and PC71BM. No
solvent additive was used for fabricating the blend films.
3.2.3. Physical properties and characteristics of optoelectronic devices of 3MTB

and 3MTT
3.2.3.1. Optical properties of polymers 3MTB and 3MTT
The UV-vis absorption spectra of the two terpolymers in the solution and thin film
states are shown in Figure 3.22. The strong intramolecular charge transfer
absorption spectral bands (π= 400~700 nm) of these D-A-containing terpolymers
(3MTB and 3MTT) were broadened and red-shifted upon incorporation of BTz or
BiTPD as strong accepting units, compared to the bands of 3MT-Th. The
absorption spectra of the thin films were red-shifted relative to those of the
solutions, indicating strong intermolecular interaction between the polymer
backbones of the terpolymers, even though the repeating units of the terpolymers
were rather disordered owing to the regio-random 3MT unit. The optical bandgaps
of 3MTB, 3MTT, and 3MT-Th were 1.78, 1.87, and 1.98 eV, respectively, as
measured from the absorption edges in the absorption spectra. This indicates that
the presence of the BTz of BiTPD units in the polymer backbones resulted in a
18


(a)

Normalized Absorbance (a. u.)

pronounced decrease in the optical bandgap owing to the strong electron
withdrawing ability of these units.
1.2

0.9

3MTB
3MTT
3MT-Th

ITIC

0.6

0.3

0.0
300

400

500

600

700

800

Wavelength (nm)

(b)

Normalized Absorbance (a.u.)

1.2

0.9

3MTB

3MTT
3MT-Th
ITIC

0.6

0.3

0.0
300

400

500

600

700

800

900

Wavelength (nm)

Figure 3.22. UV-vis absorption spectra of polymers in chloroform solutions (a) and
in films (b).
3.2.3.2. Electrochemical properties of polymers 3MTB and 3MTT
The highest occupied molecular orbital (HOMO) energy levels of these polymers
were measured by cyclic voltammetry and the lowest unoccupied molecular orbital

(LUMO) energies were calculated from the optical bandgaps and HOMO values.
The cyclic voltammograms and energy level alignment of the synthesized polymers
are displayed in Figures 3.25. The onset oxidation potentials (Eoxs) of 3MTB,
3MTT, and 3MT-Th were 1.02, 1.07, and 0.99 V, respectively, and the
corresponding HOMO levels were calculated to be -5.45, -5.50, and -5.42,
respectively. The calculated LUMO levels were -3.67, -3.63, and -3.44 eV for
3MTB, 3MTT, and 3MT-Th, respectively. The energy level offsets of the
terpolymers compared to those of ITIC, as a nonfullerene acceptor, could guarantee
strong photoinduced charge transfer between the polymer and ITIC.
19


Ferrocene
3MTB
3MTT
3MT-Th

Intensity

(a)

-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

-3.67

-3.63

-3.44

-5.50

ITIC

-5.45

3MT-Th

3MTT

-4.14

3MTB

(b)

Energy levels (eV)

E (V vs Ag/Ag+)

-5.42
-5.72

Figure 3.25. Cyclic voltammograms of the polymer films (a); energy levels of the
three polymers as donors and ITIC as the acceptor in PSCs (b).
3.2.3.3. Crystal structure of 3MTB ,3MTT
Grazing incidence wide-angle X-ray diffraction (GIWAXD) measurements
were performed for the neat films of the individual terpolymers and the as-cast
terpolymer:ITIC blend films to better understand the high performance of the
terpolymer-based PSCs (Figure 3.26). For the neat films, the terpolymers obviously
exhibited a face-on orientation, with the (010) π-π-stacking peak (d(010) = 3.94 Å for

3MTB, d(010) = 3.99 Å for 3MTT) in the out-of-plane direction. The 3MTB and
3MTT:ITIC blends also displayed a strong (010) diffraction of the π–π stacking in
the out-of-plane profiles. The data indicate that the terpolymer chains in the blend
films predominantly adopted the face-on orientation on the substrate, which is
similar to the diffraction data for the 3MT-Th:ITIC blend film. Such a polymer
chain arrangement can lead to excellent charge transport phenomena in a vertically
stacked PSC.

20


1

Intensity (a.u.)

qz (Å-1)

Intensity (a.u.)

2

(a)

Out-of-plane

In-plane

0
0

1

0.5

qxy (Å-1)

1.5

0.5

2.0

1.0

1.5

q2 (Å-1)

qq(xy)
(Å-1)

1

Intensity (a.u.)

2
Intensity (a.u.)

qz (Å-1)

(b)

1.0

Out-of-plane

In-plane

0
0

1

0.5

qxy (Å-1)

1.0

1.5

q2 (Å-1)

1

Out-of-plane

0.5

qxy (Å-1)

Intensity (a.u.)

1

0

1.0

1.5

In-plane

0.5

2.0

1.0

1.5

q2 (Å-1)

qq(xy)
(Å-1)

1

Intensity (a.u.)

2
Intensity (a.u.)

qz (Å-1)

0.5

2.0

2

0

(d)

1.5

qq(xy)
(Å-1)
Intensity (a.u.)

qz (Å-1)

(c)

1.0

Out-of-plane

In-plane

0

0

1

qxy (Å-1)

0.5

1.0

1.5

qq(xy)
(Å-1)

2.0

0.5

1.0

1.5

q2 (Å-1)

Figure 3.26. Two-dimensional GIWAXD patterns of the as-cast films of (a) 3MTB,
(b) 3MTT, (c) 3MTB:ITIC, and (d) 3MTT:ITIC. (e) Out-of-plane and in-plane XRD

patterns of pristine terpolymers and blend films.
3.2.3.4. Morphological studies of the blend films
The surface topography of the as-cast active layer with no solvent additive
was evaluated by atomic force microscopy (AFM). As shown in Figure 3c−e, the
active layers composed of the 3MTB and 3MTT:ITIC blends comprised very fine
domains with a small root-mean-square roughness (Rq) of 0.30 and 0.32 nm,
respectively. These values are slightly smaller than that of the 3MT-Th:ITIC blend
film (0.36 nm).

21


3
0

(b) 100

3MTB:ITIC (1:1.5)
3MTT:ITIC (1.2:1)
3MT-Th:ITIC (1:1)

3MTB:ITIC(1:1.5)
3MTT:ITIC(1.2:1)
3MT-Th:ITIC (1:1)

80

-3
-6

EQE (%)

Current density (mA/cm2)

(a)

-9
-12

0.8 nm

-0.8 nm

40
20

-15
-18
-0.2 0.0

60

0.2 0.4 0.6
Voltage (V)

0.8

0

1.0

400

Rq = 0.30 nm

600

700

800

Wavelength (nm)

(d)

(c)

500

(e)

Rq = 0.32 nm

Rq = 0.36 nm

Figure 3.27. (a) Current density-voltage (J-V) curves and (b) EQE spectra of PSCs
employing the as-cast polymer:ITIC blend film without solvent additives. (c−e)
AFM height images of the as-cast polymer:ITIC films. 3MTB:ITIC (a), 3MTT:ITIC
(b), 3MT-Th:ITIC (c). No solvent additive was used in the active layer.
3.2.3.5. Nonfullerene polymer solar cells

Nonfullerene BHJ PSCs were fabricated by using the synthesized
terpolymers 3MTB and 3MTT; a 3MT-Th-based PSC was also fabricated with the
same device configuration and used as a control device. An inverted type PSC
structure with the ITO/ZnO/polymer:ITIC/MoO3/Ag configuration was selected for
consistency with the literature.25 Simple device fabrication was achieved by using a
solvent-additive-free as-cast blend film of the polymer and ITIC in different blend
ratios. The performance and stability (e.g., shelf-life and operational stability) of the
PSC devices were investigated.
3.2.3.6. Shelf-life and operational stability of the PSCs
The shelf-life of the PSC devices was investigated by keeping them out of the glove
box without encapsulation under ambient conditions for over 1000 h. Interestingly,
the devices fabricated with the as-cast films of the terpolymer:ITIC blend displayed
higher PCE values, even after 1056 h.
The operational stability of the PSC devices was also investigated by continuous
irradiation (AM 1.5 G illumination at 100 mW cm−2). The device performance was
assessed periodically to observe the effect of the illumination time on degradation of
the device efficiency. The performance of all the PSC devices deteriorated with
increasing illumination /operation time. Nevertheless, the 3MTB and 3MTT-based
PSC devices displayed much better stability than the 3MT-Th-based PSCs. The
22


presence of the BTz and BiTPD units not only improved the PCE but also improved
the shelf-life and operational stability of the PSCs.
CONCLUSION AND RECOMMENDATION
1. Conclusion
The research results of the dissertation have new contributions, ensuring the
science and practice:
+ Have synthesized a new conjugated copolymers based on the
Diketopyrrolopyrrol P group (DPP6T-C4). In particular, the use of decylheptadecyl

group at 2 N sites in DPP group improves the solubility of copolymers.
+ Have synthesized 2 new wide band gap polymers: T-3MT and 2T-3MT.
These copolymers are combined with different acceptors in order to expand the
UV-Vis absorption that lead to an improvement of power conversion efficiency of
OPV devices.
+ 2 terpolymes have been synthesized: 3MTB and 3MT. OPV devices made
from these terpolymers have good properties with very high shelf-life and
operational stability, opening up their potential applications in practice.
+ From the above results, the thesis has contributed to the development of the
research direction of synthesis of semiconducting polymer for optoelectronic
applications.
2. Recommendation
Development of the research results of the thesis for the research directions
in the same field:
+ Synthesis of semiconducting polymer for optoelectronic applications.
+ Fabrication of high performance OPVs with high shelf-life and
operational stability to develop commercial product.

23