Oxygen influencing the photocarriers lifetime of CH3NH3Pbl3-xClx film grown by two-step interdiffusion method and its photovoltaic performance

During the growth of CH3NH3PbI3-xClx (MAPbI(3-x)Cl(x)) perovskite films by the two-step inter-diffusion method, the presence of a trace amount of oxygen gas is critical to their physical properties and photovoltaic performance. As the oxygen concentration increases, poor film morphologies and incomplete surface coverage are observed. Moreover, by XRD, Raman scattering, and photoluminescence measurements, we find that MAPbI(3-x)Cl(x) grains become more distorted and the electron-hole recombination rate dramatically increases. Higher oxygen concentration triggers a sharp decrease in the current density and the fill factor of corresponding solar cells, which degrades device performance, on average, from 14.3% to 4.4%. This work proves the importance of controlling the oxygen atmosphere in the fabrication of high-performance perovskite solar cells. (C) 2016 AIP Publishing LLC.