A series of benzo[1,2-b:4,5-b′]dithiophene (BDT)-based low band-gap polymers with electron-withdrawing side chains were synthesized using Stille coupling reactions. These polymers exhibited the deep HOMO levels (−5.53 to −5.65 eV) due to the incorporation of electron-withdrawing side chains. Deep HOMO levels of these polymers resulted in the higher power conversion efficiency (PCE) of 2.68% due to higher open-circuit voltage (Voc), which resulted from deep HOMO levels, compared with BDT-based low band-gap polymers without electron-withdrawing side chains.
- Kazuhiro Nakabayashi
- Hiroshi Otani
- Hideharu Mori
