Highly thermally stable non-fullerene organic solar cells: p-DTS(FBTTh2)2:P(NDI2OD-T2) bulk heterojunction

•We realize highly thermally stable p-DTS(FBTTh2)2:P(NDI2OD-T2) bulk heterojunction solar cells.•The crystalline nature of the low molecular weight compound p-DTS(FBTTh2)2 enables to stabilize the p-DTS(FBTTh2)2:P(NDI2OD-T2) blend morphology at high temperature.•The original power conversion efficiency value is retained to 70% after heating at 180 °C over 20 h.

Because long-term solar cell stability may be influenced by morphological reorganization, we investigated the effect of thermal annealing on bulk heterojunction solar cells comprised of p-DTS(FBTTh2)2:P(NDI2OD-T2) (3:1). Our results indicate that the p-DTS(FBTTh2)2) compound with lower diffusion kinetics enables to stabilize the blend morphology at high temperature, leading to high thermal stability of a p-DTS(FBTTh2)2:P(NDI2OD-T2) solar cell device. Therefore, The p-DTS(FBTTh2)2:P(NDI2OD-T2) solar cell indicates highly thermally stable bulk heterojunction device as retaining 70% of its original power conversion efficiency value after heating at 180 °C over 20 h. These results indicate that p-DTS(FBTTh2)2:P(NDI2OD-T2) is a promising BHJ system for practical use in non-fullerene OSCs.

Graphical abstractThe p-DTS(FBTTh2)2:P(NDI2OD-T2) solar cell indicates highly thermally stable bulk heterojunction device as retaining 70% of its original power conversion efficiency value after heating at 180 °C over 20 h.Figure optionsDownload full-size imageDownload as PowerPoint slide