Bridging efficiency and stability in organic solar cells: architectural design, degradation insights, and emerging mitigation strategies.

Organic solar cells (OSCs) have received much interest because of their high power conversion efficiencies (PCEs >20%), solution processability, light-weight nature, flexibility, and possibility for low-cost fabrication. Nevertheless, their commercialization is still a significant challenge due to the inability to stabilize their long-term operation. Degradation of the device can be caused either by intrinsic factors (such as the morphological instability of the bulk heterojunction (BHJ) active layer and electrodes and interfacial diffusion of the transport layers) or extrinsic factors (such as exposure to oxygen, moisture, and light, mechanical stress, etc.). These problems severely reduce the device life. This review gives an overview of the current developments in enhancing the stability of OSCs via encapsulation, introduction of additives, interfacial engineering, optimization of the active layer, and the rational molecular design of acceptor and donor materials. It focuses on the principles of degradation and possible ways to improve the efficiency and durability of organic photovoltaics. To conclude, this review identifies the prospects of developing stable, eco-friendly and efficient OSCs in the future and provides comprehensive insights into the degradation processes and mitigation plans. Because of their ability to combine efficiency, durability and environmental sustainability, OSCs can be highly significant in the transition towards next-generation renewable energy systems.