Ryu, Tae In Yoon, Youngwoon Kim, Ji-Hoon Hwang, Do-Hoon Ko, Min Jae Lee, Doh-Kwon Kim, Jin Young Kim, Honggon Park, Nam-Gyu Kim, BongSoo Son, Hae Jung 2024-01-20T09:00:57Z 2024-01-20T09:00:57Z 2021-09-02 2014-09-23 0024-9297 https://pubs.kist.re.kr/handle/201004/126334 We synthesized a series of push pull-type copolymers by copolymerizing an electron-deficient diketo-pyrrolopyrrole with three electron-donating benzodithiophene (BDT) moieties. PDPPDTT, which incorporated a dithienothiophene (DTT), showed a higher power conversion efficiency (PCE) of 6.11% compared to 3.31% for the BDT-based polymer (PDPPBDT). PDPPDTBDT, which incorporated a dithienobenzodithiophene (DTBDT), also exhibited superior performance, with a PCE of 4.75% although this value was lower than that obtained for PDPPDTT. The presence of the DTT unit in the polymer backbone lowered the energy bandgap of the polymer and induced an optimal morphology in the polymer:PC71BM blend film, resulting in higher charge carrier generation. Furthermore, the effectively delocalized frontier orbitals of PDPPDTT enhanced intermolecular interactions between the polymer chains by favoring effective pi-pi stacking, which facilitated charge carrier transport. By contrast, PDPPDTBDT unexpectedly showed a low-crystallinity thin film despite its backbone planarity, which reduced the performance relative to that of PDPPDTT. Importantly, PDPPDTT exhibited significantly better device stability compared to the other polymers in a light soaking test due to the much higher photochemical stability of PDPPDTT. We demonstrated a systematic approach to simultaneously increasing the photovoltaic performances and device stability, and we explored the basis for the structure property relationship that accompanied such improvements. English AMER CHEMICAL SOC OPEN-CIRCUIT VOLTAGE HIGH-PERFORMANCE CONJUGATED POLYMERS CHARGE-TRANSPORT SIDE-CHAINS BANDGAP THIOPHENE COPOLYMER DESIGN SEMICONDUCTOR Simultaneous Enhancement of Solar Cell Efficiency and Photostability via Chemical Tuning of Electron Donating Units in Diketopyrrolopyrrole-Based Push-Pull Type Polymers Article 10.1021/ma501300a 1 MACROMOLECULES, v.47, no.18, pp.6270 - 6280 MACROMOLECULES 47 18 6270 6280 scie scopus 000342184700015 2-s2.0-84918524225 Polymer Science Polymer Science Article OPEN-CIRCUIT VOLTAGE HIGH-PERFORMANCE CONJUGATED POLYMERS CHARGE-TRANSPORT SIDE-CHAINS BANDGAP THIOPHENE COPOLYMER DESIGN SEMICONDUCTOR organic solar cell conjugated polymer device stability