A Polymer with a Benzo[2,1-b;3,4-b′]dithiophene Moiety for Photovoltaic Applications

The characterization of a benzo[2,1‐b;3,4‐b′]dithiophene containing conjugated polymer (PBTT) is demonstrated, with regard to its photovoltaic performance. X‐ray diffraction measurements reveal that the thermal treatment results in an increased crystallinity within the PBTT:[70]PCBM network and subsequent spatial rearrangement in the film. Upon stepwise annealing, the PBTT‐based bulk‐heterojunction solar cells show an overall conversion efficiency of 2.7 % under 1 sun light illumination. The photovoltaic devices based on PBTT show a high efficiency, maintained over one month. All these aspects suggest that the use of self‐organizable materials is an efficient approach for high‐performance photovoltaic applications. The photovoltaic performance of a new benzo[2,1‐b;3,4‐b′]dithiophene‐containing conjugated polymer is demonstrated. The pairing of this polymer as donor and [70]PCBM as acceptor results in a good performance in a bulk heterojunction solar cell, featuring a power conversion efficiency of 2.7 % upon stepwise post‐annealing.