Preparation of Efficient All-Inorganic Perovskite Solar Cells from Large Grain Via 1-Heptanamine Stabilised Cspbi2br Nanoparticles with Nh4scn Additive

Abstract

CsPbI2Br is a potential material for perovskite solar cells (PSCs) due to its better thermal stability and high efficiency. Centrifugal deposition for film formation greatly simplifies the steps of the conventional anti-solvent spin coating method, but there are still problems hindering progress, such as small grain size and poor photoelectric performance. In this work, NH4SCN was introduced as an additive during the preparation of heptylamine (C7H17N) stabilised CsPbI2Br nanoparticles (NCs) and the films were prepared by centrifugal deposition. The results show that the low melting temperature compounds which formed by thiourea from NH4SCN decomposition during annealing and unreacted PbX2 would link the small grains together by melting and flowing; after PbX2 precipitation and reaction with CsX, the grain size was significantly increased by about 95% compared to that of the untreated film. Due to large grains, less defects and high crystallinity, the final power conversion efficiency and fill factor reached 12.25% and 0.70, respectively.

Keywords: All-inorganic perovskite solar cell, Nanoparticles, thiocyanate, additive engineering, grain growth