Ternary Strategy and Burn-in Degradation Investigation of Organic Solar Cells

Organic solar cells (OSCs) as a low-cost new generation of renewable energy technology have become a promising contender that could serve as an alternative to silicon to established photovoltaic (PV) technologies in the future. Meticulous active layer engineering is a crucial element for OSCs to improve the device performance, where the application of the ternary strategy is an effective pathway. The ternary strategy retains the simplicity of the fabrication for organic solar cells and exhibits a higher potential towards large-scale fabrication. Investigating the novel application of ternary strategy in OSCs is a promising method towards higher device performance. Apart from the pursuit of the device performance, research for the long-term OSCs device stability is also critical for its practical applications and future commercialization. Burn-in degradation has become an ineluctable barrier for OSCs to achieve long-time stability, where an in-depth understanding of the mechanism behind burn-in degradation has become the precondition to conquer this barrier.The aim of research works in this thesis is to improve the performance of OSCs and provide understandings of its degradation mechanism. The ternary strategy, especially incorporated with novel non-fullerene acceptor materials, as a performance improving method, is the primary focal point in this thesis. In this thesis, we derived three novel ternary OSCs and provided a comprehensive investigation of the mechanism behind its performance enhancement. On the other hand, this thesis also systematically investigated the burn-in degradation mechanism in OSCs. We analysed the degradation mechanism based on each instability factor including light, heat, and air, to gain in-depth understating. Moreover, combined with the application of ternary strategy and the burn-in degradation study, we did a case study of the burn-in degradation in the high-efficiency PTB7-Th: COi8DFIC: PC71BM ternary OSCs. We found that the ternary st