ABSTRACT:

Organic solar cells have garnered tremendous attention in recent years owing to their low cost, flexibility, lightweight, and ability to be processed over large areas using solution-based methods. With the continuous development of material systems, including novel Y-series non-fullerene acceptors, polymer donors, and self-assembled monolayer molecule interface materials, the power conversion efficiencies of organic solar cells have gradually increased to 20%. Understanding the stability of device is another important factor in photovoltaic technology. However, compared to the rapid progress in efficiency, research on device stability has lagged behind. The knowledge about the outdoor performance of devices under real-world conditions based on these novel photoactive materials remains elusive. Understanding their light-induced degradation mechanisms on both the material and device sides is urgently needed to bridge the gap between laboratory research and commercial application.

This dissertation aims to elucidate the relationship between device lifetime and the constituent materials, thereby delineating a path towards the development of resilient organic solar cells. By delving into the photostability of these devices, the major charge recombination mechanism is unveiled through electrical characterization. Moreover, an exploration of the photostability of the constituent materials in their film state, including Y-series acceptors, polymer donors, and self-assembled monolayer molecules, illustrates the correlation between their chemical structure and photostability. The byproducts generated from light exposure serve as the origins of device degradation. Furthermore, by subjecting encapsulated photostable devices to outdoor conditions, a positive correlation between outdoor stability and photostability is revealed. Combining insights into material structure with device photostability, guidelines for stable organic solar cells are raised, including designing stable photoactive materials with specific chemical structures and bi-layer transport layer strategy.