Atmospheric stable and flexible Sn-based perovskite solar cells via a bio-inspired antioxidative crystal template

Sn-based perovskite solar cells (PSCs) demonstrate a potential development in eco-friendly devices due to their hypotoxicity. However, poor stability and crystalline quality are still the challenges for achieving high-performance and long-term operating devices. In this work, inspired by biological protein, nickel-porphyrin (Ni-P) with electron cloud on conjugate ring is applied into Sn-based perovskite to prevent perovskite from being eroded. The synergistic effect of water and oxygen is broken in grain boundaries and surface so that the stability of PSCs can be improved obviously, despite there is hardly any barrier for water to erode. Simultaneously, the electron-rich molecules can passivate the defects of perovskite such as iodine vacancy. Moreover, the ester group in Ni-P molecule can bind with SnI2 to form complex and then restrain nucleation. Combining with the template effect of 2D molecular, the crystallization of perovskite films is optimized. Therefore, the Sn-based PSCs with Ni-P achieve a stabilized power conversion efficiency (PCE) of 7.79% with negligible hysteresis in flexible devices, respectively. Moreover, the PSCs can maintain 80% of the pristine PCE after 300 h under air environment.