Perovskite films with a sacrificial cation for solar cells with enhanced stability based on carbon electrodes

Abstract

Organic-inorganic lead halide perovskite solar cells have high power conversion efficiency; however, their poor environmental stability is still a problem that needs to be solved. In this study, a tetrabutylammonium cation is introduced into mixed-cation lead a mixed-halide Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 perovskite as a sacrificial cation to enhance the stability of the corresponding solar cells. Tetrabutylammonium cations located at grain boundaries are beneficial for the formation of two-dimensional perovskite grains perpendicular to the substrate during heat treatment, which can enhance the stability of solar cells against moisture. By optimizing the content of tetrabutylammonium iodide ions, a maximum power conversion efficiency of 12% is achieved for the solar cell with the structure of FTO/c-TiO2/m-TiO2/perovskite/carbon. Without encapsulation, the tetrabutylammonium contained perovskite solar cell does not obviously degrade at ambient atmosphere (60% relative humidity and 27 °C) for over 1000 h. Moreover, this solar cell can retain over 80% of its initial efficiency for 500 h at 85 °C and in dry air.