Stable and scalable 3D-2D planar heterojunction perovskite solar cells via vapor deposition.

Abstract The device stability and toxic-solvent-free processing are indispensable development to industrialize organometal halide perovskite solar cells. In this work, the conventional top surface of vapor prepared 3D-MAPbI 3 was replaced by 2D-(BA) 2 (MA) n‐1 Pb n I 3n+1 perovskite platelet via molecular substitution from MA (CH 3 NH) to BA (C 4 H 9 NH 2). Our fully vapor process fabricated a 3D-2D perovskite heterojunction for solar cell application, realizing the power conversion efficiency as high as 16.50% and the average one as 15.40%. Furthermore, unencapsulated devices can sustain their 81% efficiency after 30 days under 55% RH, and also 74% efficiency after 30 days under 80 °C heat stress. Stability of humidity resistance arises from the reduced n value of 2D perovskite caused by the surface reaction of moisture, and the improvement of thermal stability comes from the buffering of MA molecules release. Meanwhile, the fabrication of large scale device with high efficiency is also demonstrated in our experiment. Graphical abstract Image 1 Highlights • 3D-2D heterojunction perovskite solar cells were fabricated by vapor deposition. • 3D-2D device shows champion PCE of 16.50% and the stability has been greatly improved compare with 3D device. • The stability mechanism for 2D perovskite layer to protect 3D perovskite is explained. • The potential of scale up fabrication is demonstrated. [ABSTRACT FROM AUTHOR]