Regulating buried interface properties and alleviating micro-strain of crystals for efficient perovskite solar cells.

Surface properties of SnO 2 and their effects on the growth of perovskite films play a crucial role for perovskite solar cells (PSCs). Herein, a facile strategy to synchronously regulate the buried interface defects and energy level arrangement, as well as improve the crystallinity of perovskite films with alleviated micro-strain by pre-modifying the SnO 2 surface with ammonium hexafluorophosphate (NH 4 PF 6 ) is proposed. The device achieved the promising PCE of 22.50% and improved stability.