title: Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI2Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy.
abstract: The presence of the PbI2passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CH3NH3PbI3perovskite crystals and PbI2passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains. By systematically exploring the interfacial electronic structures of individual perovskite grains, enhanced charge separation and reduced back recombination were observed when an optimal design of interfacial PbI2passivation layers consisting of a thickness less than 20 nm at perovskite crystal grains was applied.
authors.affiliation: Department of Physics, National Sun Yat-sen University , Kaohsiung 804, Taiwan.
authors.forename: Min-Chuan
authors.initials: MC
authors.lastname: Shih
authors.forename: Shao-Sian
authors.initials: SS
authors.lastname: Li
authors.affiliation: Department of Physics, National Sun Yat-sen University , Kaohsiung 804, Taiwan.
authors.forename: Cheng-Hua
authors.initials: CH
authors.lastname: Hsieh
authors.forename: Ying-Chiao
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Department of Physics, National Sun Yat-sen University , Kaohsiung 804, Taiwan.
authors.forename: Hung-Duen
authors.identifier: 0000-0002-5257-532X
authors.initials: HD
authors.lastname: Yang
authors.affiliation: Department of Physics, National Sun Yat-sen University , Kaohsiung 804, Taiwan.|Institute of Physics, Academia Sinica , Nankang, Taipei 115, Taiwan.|Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology , Taipei 106, Taiwan.
authors.forename: Ya-Ping
authors.identifier: 0000-0001-7065-4411
authors.initials: YP
authors.lastname: Chiu
authors.affiliation: Institute of Physics, Academia Sinica , Nankang, Taipei 115, Taiwan.
authors.forename: Chia-Seng
authors.initials: CS
authors.lastname: Chang
authors.affiliation: Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology , Taipei 106, Taiwan.
authors.forename: Chun-Wei
authors.identifier: 0000-0003-3096-249X
authors.initials: CW
authors.lastname: Chen
mesh_terms: D017610:Calcium Compounds; D004581:Electronics; D006046:Gold / Q000737:chemistry; D007854:Lead / Q000737:chemistry*; D008029:Lighting / Q000379:methods; D016252:Microscopy, Scanning Tunneling / Q000295:instrumentation; D061848:Optical Imaging / Q000379:methods*; D010087:Oxides; D012993:Solar Energy; D013499:Surface Properties; D014025:Titanium
chemical_list: D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D007854:Lead; C029891:lead chloride; D006046:Gold; D014025:Titanium
keywords: PbI2 passivation layer; Perovskite-based solar cells; heterointerface; scanning tunneling spectroscopy