1160106-14-8Relevant articles and documents
Synthesis and characterization of bridged bithiophene-based conjugated polymers for photovoltaic applications: Acceptor strength and ternary blends
Chen, Chiu-Hsiang,Hsieh, Chao-Hsiang,Dubosc, Martin,Cheng, Yen-Ju,Hsu, Chain-Shu
, p. 697 - 708 (2010)
Six of three-component donor-acceptor random copolymers P1-P6, symbolized as (thiophene donor)m -(thiophene acceptor)n, were rationally designed and successfully synthesized by the palladium-catalyzed Stille coupling. The 4H-cyclopenta[2,l-b:3,4-b']dithiophene (CPDT) unit serves as the donor for Pl-P4, while the benzothiadiazole (BT), quinoxaline (QU), dithienoquinoxaline, and thienopyrazine (TP) units are used as the acceptor for P1, P2, P3, and P4, respectively. P5 and P6 are structurally analogous to P1 and P2 except for using the dithieno[3,2-b:2',3'-d]silole (DTS) unit as the donor. Because the band gap lowering ability of the acceptor units in the polymer is in the order TP > BT > QU presumably due to the quinoid form population in the polymers, the optical band gaps can be well adjusted to be 1.2,1.6, and 1.8 eV for P4, P1, and P2, respectively. It is found that the two bridged bithiophene units, CPDT and DTS, have similar steric and electronic effects on the P1 and P5 as well as P2 and P6, respectively, leading to comparable intrinsic properties and device performances. Bulk heterojunction photovoltaic cells based on ITO/PEDOT:PSS/polymer:PC7BM/Ca/Al configuration were fabricated and characterized. Although P4 exhibits the lowest optical band gap, broadest absorption spectrum, and highest mobility, the too low-lying LUMO level hinders the efficient exciton dissociation, resulting in a low PCE of 0.7%. Compared with poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b'] dithiophene)-alt-4,7-(2,l,3-benzothiadiazole)] (PCPDTBT), random copolymer P1 shows more blue-shifted, broader absorption spectrum, comparable mobility, and a higher PCE of 2.0%. In view of the fact that P1 shows a higher band gap with strong absorption in visible region, while PCPDTBT has a lower band gap to mainly absorb NIR light, a BHJ device with the active layer containing ternary blend of PCPDTBT/P1/PC71BM was investigated and achieved an enhanced PCE of 2.5%, which outperforms the devices based on the binary blending systems of PCPDTBT/ PC71BM(PCE = 1.4%)orP1/PC71BM(PCE = 2.0%) under the identical conditions. Such an improvement is ascribed to the complementary absorption and compatible structure of P1 and PCPDTBT polymers.
Optoelectronic Properties of A-π-D-π-A Thiophene-Based Materials with a Dithienosilole Core: An Experimental and Theoretical Study
Caselli, Monica,Vanossi, Davide,Buffagni, Mirko,Imperato, Manuel,Pigani, Laura,Mucci, Adele,Parenti, Francesca
, p. 1314 - 1323 (2019/05/15)
Two A-π-D-π-A thiophene-based small molecules with a central dithienosilole core and dicyanovinyl (DCV) end groups were synthesized. These compounds differ only by the presence of alkyl and alkylsulfanyl chains, respectively, on the thiophene beta positions. Computational data together with the spectroscopic and electrochemical findings (obtained by means of absorption, steady-state/time-resolved emission techniques, and cyclic voltammetry) revealed that both molecules possess low electronic and optical band gaps, broad absorption spectra, and good stability both in p and n-doping states, which make them suitable for optoelectronic applications. In both compounds, the HOMO–LUMO transition involves an intramolecular charge transfer from the electron-donor dithienosilole unit to the two terminal electron-acceptor DCV groups. A marked positive emission solvatochromism was observed for both molecules and was interpreted on the basis of the symmetry breaking in the S1 excited state. The two synthesized compounds were also compared to their shorter precursors and to similar oligothiophenes to understand how the nature of the building block influences the characteristics of the final materials. Furthermore, it was possible to better understand the contribution of the sulfur atom in modulating the optical properties of the small molecules studied.
Semiconductor materials prepared from dithienylvinylene copolymers
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, (2016/01/20)
Disclosed are new semiconductor materials prepared from dithienylvinylene copolymers with aromatic or heteroaromatic π-conjugated systems. Such copolymers, with little or no post-deposition heat treatment, can exhibit high charge carrier mobility and/or good current modulation characteristics. In addition, the polymers of the present teachings can possess certain processing advantages such as improved solution-processability and low annealing temperature.