Recent Progress and Challenges Towards Highly Stable Nonfullerene Acceptor-Based Organic Solar Cells

Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) have made significant breakthrough in their device performance, now achieving a power conversion efficiency of ~18% for single junction devices, driven by the rapid development in their molecular design and device engineering in recent years. However, achieving long-term stability remains a major challenge to overcome for their commercialization, due significantly to the current lack of understanding of their degradation mechanisms as well as the design rules for enhancing their stability. In this review, we focus specifically on the recent progress on understanding the degradation mechanisms and enhancing the stability of high performance NFA-based OSCs. We first provide an overview of the recent advances in the molecular design and device engineering of several classes of high performance NFA-based OSCs for various targeted applications, before presenting a critical review of the different degradation mechanisms identified through photochemical-, photo-, and morphological degradation pathways. Potential strategies to address these degradation mechanisms for further stability enhancement, from molecular design, interfacial engineering and morphology control perspectives, are also discussed. Finally, an outlook will be given highlighting the remaining key challenges toward achieving the long-term stability of NFA-OSCs