A first-principles prediction on the "healing effect" of graphene preventing carrier trapping near the surface of metal halide perovskites. Issue 13 (6th March 2018)

• Record Type: Journal Article
• Authors: Wang, W.-W.; Dang, J.-S.; Jono, R.; Segawa, H.; Sugimoto, M.
• Is Part Of: Chemical science. Volume 9:Issue 13(2018)
• Page Start: 3341
• Page End: 3353
• Publication Date: 2018-03-06
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7sc04837h
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : We introduce a healing effect of graphene preventing carrier trapping by the defects near the surface of metal halide perovskites. Abstract : We herein report that surface modification of metal halide perovskites using graphene would be beneficial to improving the energy conversion efficiencies of perovskite solar cells. The present first-principles calculations on MAPbI3 with a single vacancy created by removing either I, Pb or MA show that the I and Pb vacancies near the surface result in the formation of Pb–Pb and I–I dimers, respectively. They are predicted to yield mid-gap levels, and would degrade the energy conversion efficiency of perovskite solar cells through carrier trapping. The present calculations suggest that when the surface of MAPbI3 is covered with a graphene sheet, the formation of the carrier trapping dimers would be suppressed. The origin of the "healing effect" of graphene on the lattice defect is ascribed to electronic interactions on the surface, which prevent charge localization at the lattice defects beneath the surface.