Modified structure of two-dimensional polythiophene derivatives by incorporating electron-deficient units into terthiophene-vinylene conjugated side chains and the polymer backbone: synthesis, optoelectronic and self-assembly properties, and photovoltaic application

Abstract

Molecular engineering on the conjugated side chains of two-dimensional (2D) conjugated polymers was conducted and its effect on the optical, electronic, self-assembly and photovoltaic properties was investigated. A new monomer, M2, was prepared by capping (E)-3 0 -(2-(2,5-dibromothiophen-3-yl)vinyl)-4,4 00 -bis(2-ethylhexyl)-2,2 0 :5 0 ,2 00 -terthiophene, M1, with two heptanoyl groups, and then coupled with 5,5 0 -bis(trimethylstannyl)-2,2 0 -bithiophene via microwave-assisted Stille polymerization to produce a series of polythiophene derivatives with terthiophene-vinylene conjugated side chains, TTV-PTs.Copolymer P2 shows a down-shifted HOMO energy level, enhanced solubility, and red-shifted absorption, as compared with P1; however, the bulky side chains significantly disrupt the coplanarity of thiophene rings in the polymer backbone and the ability to self-assemble into an ordered structure. The GIXRD measurements reveal that the original crystallinity of P1 can be recovered by simply inserting a few 2,1,3-benzothiadiazole units into the polythiophene main chain in P2 through a random copolymerization route to yield a terpolymer, P3, which possesses excellent crystallinity, thereby causing a three-fold increment in hole mobility. Furthermore, the P1/PC 61 BM, P2/PC 61 BM, and P3/PC 61 BM solar devices exhibit power conversion efficiencies of 3.89%, 1.52%, and 4.17%, respectively, under AM1.5G illumination with an intensity of 100 mW cm À2 .

Conjugated Random Terpolymer Donors towards High‐Efficiency Polymer Solar Cells

“…Wang et al . reported a new PTs‐based random terpolymer TD3 by employing thiophene with terthiophene‐vinylene (TTV) side chain, 2,1,3‐benzothiadiazole (BT) and bithiophene as repeating units . As anticipated, the introduction of TTV side chain down shift the HOMO energy level and improve the solubility.…”

Synthesis and Characterization of Two-Dimensional Conjugated Polymers Incorporating Electron-Deficient Moieties for Application in Organic Photovoltaics

“…The two-dimensional grazing incident X-ray diffraction (2D-GIXRD) samples were prepared by drop-casting from CB solution (10 g/L) on 10 mm × 10 mm Si wafers substrate and then thermal annealing at 120 °C, 20 min. 2D-GIXRD measurements were carried out on the wiggler beamline BL17A1 of the National Synchrotron Radiation Research Center (NSRRC, Hsinchu, Taiwan), with a wavelength of 1.333 Å delivered from a superconducting wavelength-shifting magnet and a Si (111) triangular crystal monochromator (TCM) [ 26 , 33 ]. The data were recorded by a Mar3450 image plate with exposure duration 60 s. The two-dimensional diffraction pattern was converted to a one-dimensional powder diffraction profile by fit-2D program.…”

“…The polymer solar cells (PSCs) were fabricated with the structure of ITO/PEDOT:PSS/polymer:PC 61 BM/Ca/Al from our previous work [ 20 , 26 ]. The ITO glasses were cleaned by a sequential ultrasonic treatment in detergent, deionized water, acetone, and isopropanol for 20 min.…”

“…In our previous studies, terthiophene–vinylene (TTV)-based conjugated polymers possess a broader absorption region and deeper HOMO levels than rr-P3HT [ 20 , 25 , 26 ]. Herein, a novel 2-D polymer PTTVBDT, as shown in Figure 2 , has been designed and synthesized by cooperating TTV and BDT units via Stille polymerization.…”

Large thermoelectric efficiency of doped polythiophene junction: A density functional study

“…Polythiophene (PT) is one of the famous and applicable p-conjugated molecules, with thiophene (T) rings are located in antiposition states to each other and has non-degenerated ground state. Because of its potential in integrating optical and electronic devices, it is important to investigate the thermoelectric properties of PT and its derivative based devices [19][20][21][22]. Asaduzzaman et al studied the change in electronic properties of PT via replacing of some hydrogen atoms (H) by nitrogen atoms (N) and methyl (CH3) group based on density functional theory (DFT) [23].…”