Effect of thermal annealing on the performance of PTB7-Th:PC70BM–based ternary organic solar cells

Abstract

Molecular design, processing method and device engineering are some important strategies to improve the performance of organic solar cells (OSC). In this study, we investigate the influence of the thermal annealing (TA) treatment on the performance of ternary OSC based on PTB7-Th:PC70BM bulk heterojunction incorporating a newly designed solution-processable phthalocyanine small molecule, copper fluorinated phthalocyanine (CuPcF48). The addition of CuPcF48 as a third component has shown to improve the power conversion efficiency (PCE) of up to 7% in ternary OSC compared to binary OSC through molecular design and ternary strategies. On the other hand, employing device engineering through TA treatment, a drop in PCE for both binary and ternary OSC upon thermal annealing were observed. The results suggest that the device engineering strategy by thermal annealing treatment may not suitable for the device improvement of PTB7-Th:PC70BM-based blend.