Synthesis of Small-Molecule-Dyes Based on Ethyl-4H-Chromen-4-Ylidene Malononitrile as Electron-Withdrawing Group for OSCs

다국어 초록 (Multilingual Abstract)

Two new acceptor-donor-acceptor (A-D-A) type conjugated small molecule donors, denoted as IDTT-CMCN and IDTT-HT-CMCN, based on indacenodithieno[3,2-b]thiophene (IDTT) and 2-(2-methyl-4H-chromen-4-ylidene)malononitrile (CMCN), have been synthesized for application in organic solar cells. In these A-D-A type small-molecules IDTT is the electron donating unit while CMCN is the electron-withdrawing unit. In comparison with IDTT-CMCN, IDTT-HT-CMCN has 3-hexylthiophene (HT) as a π-bridge unit between the IDTT and CMCN moieties to increase the solubility and extend the π-conjugation length. OSCs based on both of these donors and PC71BM as the acceptor were fabricated to investigate the effect of alkylthiophenes on the photovoltaic properties. As a result, the IDTT-HT-CMCN showed a power conversion efficiency (PCE) as high as 7.60% with a short circuit current of 12.7 mA/cm², open circuit voltage of 0.94 V, and fill factor of 63.8%.