Bilayer layer-by-layer structures for enhanced efficiency and stability of organic photovoltaics beyond bulk heterojunctions

Tanya Kumari, Irina Vyalih, Miguel Ángel León Luna, Hamsa Ahmed, Mariam Ahmad, Rovshen Atajanov, Eswaran Jayaraman, Suraj Manikandan, Barbara Paci, Aldo Di Carlo, Jens Wenzel Andreasen, Vida Turkovic, Morten Madsen

Abstract: Tuning bulk heterojunctions is an important step for improving organic photovoltaic device performance; however, challenges remain in obtaining sufficient device lifetimes using this concept. In this work, we report on high-performance PM6/Y7 layer-by-layer organic photovoltaic devices by carefully tuning the layer-by-layer structure and studying the effects on device performance. We demonstrate that an optimized layer-by-layer organic photovoltaic can effectively improve the photophysical properties of the device, resulting in a conversion efficiency of 16.21%, surpassing the bulk heterojunction counterpart. Notably, the developed layer-by-layer device also outperforms the traditional bulk heterojunction in terms of long-term photostability and thermal stability under continuous illumination and temperature stress (85°C) for approximately 1,000 h, with similar results obtained for eight other non-fullerene acceptor systems. The improved long-term photostability and thermal stability in these layer-by-layer systems is ascribed to a mitigation of the strong phase aggregation seen in the bulk heterojunction films.

External IDs:doi:10.1016/j.xcrp.2024.102027