3,5-dichlorobenzylamine lead high-performance and stable 2D/3D perovskite solar cells

Organic–inorganic lead halide peroxides (OIHPs) have attracted much interest due to their excellent photovoltaic properties, but practical applications are limited by long-term stability and further performance enhancement. Two-dimensional/three-dimensional (2D/3D) heterojunction is a promising strategy to address these issues. Here, short-chain 3,5-dichlorobenzylamine (DBA) with halogen functional groups is introduced to react with excess PbI 2 to form the 2D perovskite layer in mixed perovskite films of Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 , which passivates surface defects, favours energy band alignment of functional layers and suppresses non-radiative recombination of carriers. As a result, DBA-treated 2D/3D PSCs obtained a champion PCE of 21.54% with an improved open circuit voltage ( V oc ) of 1.171 V. More importantly, the 2D/3D heterojunction can effectively protect the underlying 3D perovskite from moisture ingress. The unencapsulated 2D/3D devices retain 90% of their initial efficiency even after aging at 40 ± 5% RH for 1000 h, while the 3D device retains only 40%.