Enhanced efficiency and light stability of planar perovskite solar cells by diethylammonium bromide induced large-grain 2D/3D hybrid film

In this work, diethylammonium bromide (DABr) is used in planar perovskite solar cells to post-treat methylammonium iodide (MAPbI(3)) films to fabricate high quality 2D/3D perovskite hybrid films. DABr treatment not only induces the small crystals secondary growth into large crystals, which lead to the formation of large-grain 3D perovskite films, but also forms a 2D DA(2)PbI(4-x)Br(x) capping layer on the MAPbI(3) surface. The 2D DA(2)PbI(4-x)Br(x) capping layer improves the moisture stability of the films. The larger grains and better crystallized 2D/3D perovskite films with fewer defects and interfacial contact between TiOx layer and active layer are beneficial to eliminate the light soaking effect and enhances the light stability. Transient PL spectra reveal that the 2D layer can act as an interface modification layer to promote the photogenerated carrier dissociation and hole extraction. By applying MAPbI(3) and 2D/3D perovskite film as light absorbers in PVSCs, we are able to enhance PCE from 14.37% to 18.30%.