Alcohol assistant surface passivated perovskites for efficient perovskite solar cells

Abstract

The surface passivation has been intensively applied for diminishing surface defects, restricting leakage current and suppressing surface charge recombination, aimed to boost device performance of perovskite solar cells (PSCs). In this work, we report the utilization of alcohol to treat the surface of methylammonium lead iodide (CH 3 NH 3 PbI 3 , MAPbI 3 ) thin film for generating excess PbI 2 as a surface passivation layer. X-ray diffraction, grazing-incident wide-angle x-ray scattering, and morphological studies reveal that additional PbI 2 is indeed formed at the surface of MAPbI 3 thin films with alcohol treatment. Photoluminescence studies demonstrate that the non-radiative charge recombination is suppressed within the butanol-treated MAPbI 3 thin film. The optimal film morphology is obtained from the butanol-treated MAPbI 3 thin film. The enlarged recombination resistance, reduced trap density, and improved build-in potential are observed from the PSCs based on the butanol-treated MAPbI 3 thin film compared to those based on either pristine MAPbI 3 or the ethanol- or isopropanol-treated MAPbI 3 thin films, respectively, indicating the surface charge recombination is restricted and the interface defects are suppressed within the butanol-treated MAPbI 3 thin film. As a result, a power conversion efficiency (PCE) of 20.44% is observed from the PSCs based on the butanol-treated MAPbI 3 thin film in comparison with a PCE of 17.24% from the PSCs based on the pristine MAPbI 3 thin film. Our findings demonstrate that we have developed a facile way to approach efficient PSCs through PbI 2 surface passivation of MAPbI 3 thin films with alcohol treatment. • Development of efficient perovskite solar cells (PSCs) through surface passivation layer. • We report the utilization of various alcohols to treat the surface of methylammonium lead iodide (CH 3 NH 3 PbI 3 , MAPbI 3 ) thin film for generating excess PbI 2 as a surface passivation layer. It is found that the optimal film morphology is obtained from the butanol-treated MAPbI 3 thin film. • The enlarged recombination resistance, reduced trap density, and improved build-in potential are observed from the PSCs based on the butanol-treated MAPbI 3 thin film compared to those based on either pristine MAPbI 3 or the ethanol- or isopropanol-treated MAPbI 3 thin films, respectively, indicating the surface charge recombination is restricted and the interface defects are suppressed within the butanol-treated MAPbI 3 thin film. • A power conversion efficiency (PCE) of 20.44% is observed from the PSCs based on the butanol-treated MAPbI 3 thin film in comparison with a PCE of 17.24% from the PSCs based on the pristine MAPbI 3 thin film. Our findings demonstrate that we have developed a facile way to approach efficient PSCs through PbI 2 surface passivation of MAPbI 3 thin films with alcohol treatment.