Fabrication of efficient and stable wide band gap CsPbIBr2 inorganic perovskite solar cells via doping with lead chloride compound

Abstract

Currently, CsPbX3 (X = I, Br, Cl) wide bandgap inorganic perovskite solar cells (PSCs) with superior thermal stability and excellent photoelectric performance have received great attention in the photovoltaic community, showing great potential for the applications of tandem devices and building integrated photovoltaics (BIPV). Among them, CsPbIBr2 is considered as the most promising light-absorbing layers to balance performance and stability. However, its power conversion efficiency (PCE) is still lagging far behind other inorganic perovskites. It mainly attributes to the effect of sever intrinsic self-doping defect which always results in small grain size, low film coverage, and large carrier recombination. Herein, Lead Chloride (PbCl2) compound is firstly incorporated into CsPbIBr2 precursor solution to prepare CsPbIBr2−xClx wide bandgap films, and its optimal doping concentration is systematic studied in this work. Surprisingly, after the doping of PbCl2, the number of pinholes in perovskite films significantly decreased and impressive micron sized grains appeared. Besides, the improvement of crystal quality and the reduction of defect density effectively reduce the recombination of charge carriers inside the device. Hence, the optimized CsPbIBr2−xClx with a wide bandgap of 2.09 eV gains a PCE of 9.38 % and shows good thermal stability.