Sp-hybridized carbon enabled crystal lattice manipulation, pushing the limit of fill factor in β-CsPbI3 perovskite solar cells

Abstract

Due to their superior thermal stability, inorganic perovskites, especially CsPbI₃, possess great application prospects. However, non-radiative recombination energy dissipation caused by defect states has always been a technical bottleneck restricting the development of perovskite solar cells. Herein, graphdiyne (GDY), an sp-hybridized carbon framework, has been introduced to manipulate the CsPbI₃ perovskite crystal lattice. On the one hand, GDY serves as a Lewis base, thereby regulating the perovskite crystallization process and leading to high-quality thin film with low-defect state density. On the other hand, the GDY molecule at grain boundaries relieves the inevitable crystal lattice stress within the CsPbI₃ perovskite film caused by the high thermal annealing temperature. As a result, a record-high fill factor of 83.96% and an ultra-high open-circuit voltage of 1.191 V for β-phase CsPbI₃ perovskite solar cells are achieved simultaneously. This work provides a proficient methodology to manipulate the crystal lattice of inorganic perovskites toward high-performance photovoltaics.