Broadening the light absorption range via PBDB-T to improve the power conversion efficiency in ternary organic solar cells

In recent years, ternary organic solar cells, which enable extended spectral response range compared to their binary counterpart, have been emerging as an attractive strategy for obtaining impressive photovoltaic properties. In this work, the third component of PBDB-T with a medium bandgap was introduced into PBT7-Th: PC71BM host system to fabricate high efficiency ternary solar cells. It was revealed that PBDB-T not only broadens the light absorption range, but also provides pathway for energy transfer via a Firster resonance energy transfer (FRET) regime. Finally, a champion PCE of 9.45% is achieved for the bulk heterojunction (BHJ) ternary solar cells with 15 wt% PBDB-T, which is 11% enhancement in PCE compared with the host binary OSCs. These results indicate that broadening absorption range is an effective strategy to improve OSCs performance.