All-inorganic 2D/3D Csx+2Pbx+1(SCN)2(I/Br)3x+2 perovskites

Abstract

All-inorganic quasi two-dimensional (quasi-2D) or two/three-dimensional (2D/3D) mixed perovskites are still in their infancy, even though they are expected to inherit the advantages of quasi-2D perovskites and all-inorganic perovskites employed in solar cells, light-emitting diodes, and detectors. Herein, we studied a series of all inorganic 2D/3D halide perovskite materials, Cs_x+2Pb_x+1(SCN)₂(I/Br)_3x+2. Different from common organic–inorganic hybrid quasi-2D perovskites exhibiting phase mixtures of different inorganic sheets, the Cs_x+2Pb_x+1(SCN)₂(I/Br)_3x+2 (x = 1, 2, 3) phases only consist of 2D Cs₂Pb(SCN)₂(I/Br)₂ and 3D CsPb(I/Br)₃ perovskite phases (here x defines the ratio of 3D CsPb(I/Br)₃ and 2D Cs₂Pb(SCN)₂(I/Br)₂ perovskite phases). Based on the optimized morphology from the Pb(Ac)₂ additive and hexadecyltrimethylammonium iodide (CTAI) passivation, the devices based on Cs_x+2Pb_x+1(SCN)₂I_3x+2 (x = 3) achieve a PCE of 8.1%.