Efficiency Enhancement of Wide Bandgap Lead Perovskite Solar Cells with PTAA Surface-Passivated with Monomolecular Layer from the Viewpoint of PTAA Band Bending

Abstract

Thisreport is on the efficiency enhancement of wide bandgap leadhalide perovskite solar cells (WBG Pb-PVK PSCs) consisting of FA(0.8)Cs(0.2)PbI(1.8)Br(1.2) as thelight-harvesting layer. WGB Pb-PVK PSCs have attracted attention asthe top layer of all perovskite-tandem solar cells. Poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] (PTAA), a conductive polymer, is alwaysused as the hole transporting layer (HTL) for Pb-PVK PSCs. Nevertheless,the hydrophobic surface of the PTAA sometimes destroys the growthof the FA(0.8)Cs(0.2)PbI(1.8)Br(1.2) film. On the other hand, the Fermi level of PTAA is not well matchedwith that of perovskite film. Thus, the PCE of the WBG Pb-based PSCswith PTAA as the HTL was not very high. In this report, the efficiencyof the FA(0.8)Cs(0.2)PbI(1.8)Br(1.2) is improved by passivating the surface of the PTAA with a monomolecularlayer, where the surface becomes hydrophilic, and the band bendingof the PTAA layer is improved to cause swift hole collection. Finally,WBG Pb-PVK PSCs (1.77 eV) with 16.52% efficiency are reported.