Anti-naphthalene bisbenzimidazole columnar mesogens as interfacial modifiers in perovskite solar cells

Abstract

Introducing an interfacial layer is a strategic way to improve the performance and stability of perovskite solar cells by optimizing charge transport, reducing recombination, and enabling proper energy level alignment. In conventional perovskite solar cells, the commonly used hole transport layer, spiro-OMeTAD, is limited by its poor hole mobility, low intrinsic conductivity and susceptibility, which result in interfacial defects and device degradation. To address these challenges, we developed organically self-assembled semiconductors utilizing anti-naphthalene bisbenzimidazole (NB20) as an interfacial layer between the perovskite and spiro-OMeTAD. The NB20 layer enhances hole extraction, passivates the interfacial defects, and improves charge transport, leading to an approximately 9% performance boost through better energy level alignment and lower recombination losses. Additionally, the modified device with the passivated layer shows enhanced stability by maintaining 80.69% of its original power conversion efficiency after 1000 hours, whereas unmodified devices have retained only 58.73% of their initial performance.