title: PbI2-HMPA Complex Pretreatment for Highly Reproducible and Efficient CH3NH3PbI3Perovskite Solar Cells.
abstract: Interfacial engineering of the meso-TiO2surface through a modified sequential deposition procedure involving a novel PbI2-HMPA complex pretreatment is conducted as a reproducible method for preparing MAPbI3based perovskite solar cells providing the highest efficiencies yet reported with the polymer HTM layer. Grazing-incidence X-ray diffraction depth profiling confirms the formation of a perovskite film with a PbI2-rich region close to the electron transport layer (ETL) due to the strong interaction of HMPA with PbI2, which successfully retarded the dissolution of the PbI2phase when depositing the perovskite layer on top. These results are further confirmed by energy-dispersive X-ray spectroscopy performed in a scanning transmission electron microscope, which reveals that the I/Pb ratio in samples treated with the complex is indeed reduced in the vicinity of the ETL contact when compared to samples without the treatment. The engineered interface leads to an average power conversion efficiency of 19.2% (reverse scan, standard deviation SD < 0.2) over 30 cells (best cell at 19.5% with high FF of 0.80).
authors.affiliation: School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, China.|Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.|Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300072, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.affiliation: Interdisciplinary Centre for Electron Microscopy, EPFL , CH-1015 Lausanne, Switzerland.
authors.forename: Emad
authors.initials: E
authors.lastname: Oveisi
authors.affiliation: Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Photovoltaics and Thin Films Electronics Laboratory, EPFL Neuchâtel , CH-2002 Neuchâtel, Switzerland.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Jeangros
authors.affiliation: Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.
authors.forename: Giulia
authors.initials: G
authors.lastname: Grancini
authors.affiliation: Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.
authors.forename: Sanghyun
authors.initials: S
authors.lastname: Paek
authors.affiliation: School of Chemical Engineering and Technology, Tianjin University , Tianjin 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300072, China.
authors.forename: Yaqing
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Group for Molecular Engineering of Functional Materials, EPFL Valais Wallis , CH-1951 Sion, Switzerland.
authors.forename: Mohammad Khaja
authors.initials: MK
authors.lastname: Nazeeruddin