Chemo-thermal surface dedoping for high-performance tin perovskite solar cells

Removing the lead (Pb) from state-of-the-art perovskite solar cells (PSCs) while maintaining high power conversion efficiencies (PCEs) is a prominent step toward full commercialization. The field has identified tin (Sn) PSCs as a promising alternative, but the performance of these Sn PSCs are limited primarily by detrimental Sn(IV) self-doping. Herein, we demonstrate Sn PSCs with PCEs up to 14.7% via a surface-dedoping approach. This method features the chemo-thermal removal of Sn(IV) self-dopants that are found mainly accumulated on the surface of Sn perovskite thin films, and its optimization can avoid negative effects on film morphology. Using this method, we show about a 3-fold enhancement in carrier lifetime and a 2-fold reduction in trap density, underpinning the device's efficiency improvement. The Sn PSCs are also stable, with a 92% PCE retention after 1,000 h of storage in a nitrogen-filled glovebox. This work paves a way for PSCs to achieve their technological potential without Pb involvement.