Efficient PTB7-Th:Y6:PC71BM ternary organic solar cell with superior stability processed by chloroform

Blend morphology is crucial for the efficiency and stability of organic solar cells. Exploring and understanding the correlations between is meaningful and greatly desired. In this work, based on polymer donor (PTB7-Th), fullerene and non-fullerene acceptors (PC71BM and Y6), we systematically study the influence of ternary strategy and solvent system on device performance and stability. It is found that insufficient and excessive phase separation of blend could result in the depressed performance of corresponding devices. Appropriate phase separation/blend morphology can be achieved by utilizing a ternary strategy or suitable solvent. Chloroform-processed ternary blend PTB7-Th:Y6:PC71BM delivers efficiency of 9.55%, with dramatically enhanced J(SC) of 24.68 mA cm(-2) due to optimized absorption, blend morphology and optoelectmnic properties. More importantly, superior device stability is demonstrated for the optimal ternary device under both thermal stress and maximum power point operation, by maintaining 80% of initial efficiency at 85 degrees C for 880 h and presenting almost zero efficiency decay in 200 h under MPP operation.

Automated summary

The research reveals the importance of appropriate phase separation/blend morphology in device performance, which can be achieved through the use of a ternary strategy or suitable solvent.