title: Alkali Metal Halide Salts as Interface Additives to Fabricate Hysteresis-Free Hybrid Perovskite-Based Photovoltaic Devices.
abstract: A new method was developed for doping and fabricating hysteresis-free hybrid perovskite-based photovoltaic devices by using alkali metal halide salts as interface layer additives. Such salt layers introduced at the perovskite interface can provide excessive halide ions to fill vacancies formed during the deposition and annealing process. A range of solution-processed halide salts were investigated. The highest performance of methylammonium lead mixed-halide perovskite device was achieved with a NaI interlayer and showed a power conversion efficiency of 12.6% and a hysteresis of less than 2%. This represents a 90% improvement compared to control devices without this salt layer. Through depth-resolved mass spectrometry, optical modeling, and photoluminescence spectroscopy, this enhancement is attributed to the reduction of iodide vacancies, passivation of grain boundaries, and improved hole extraction. Our approach ultimately provides an alternative and facile route to high-performance and hysteresis-free perovskite solar cells.
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Dhanashree
authors.initials: D
authors.lastname: Moghe
authors.affiliation: Department of Engineering Physics, Polytechnique Montreal , Montréal, H3T 1J4 Québec, Canada.
authors.forename: Soroush
authors.initials: S
authors.lastname: Hafezian
authors.forename: Pei
authors.initials: P
authors.lastname: Chen
authors.forename: Margaret
authors.initials: M
authors.lastname: Young
authors.forename: Mark
authors.initials: M
authors.lastname: Elinski
authors.affiliation: Department of Engineering Physics, Polytechnique Montreal , Montréal, H3T 1J4 Québec, Canada.
authors.forename: Ludvik
authors.initials: L
authors.lastname: Martinu
authors.affiliation: Department of Engineering Physics, Polytechnique Montreal , Montréal, H3T 1J4 Québec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Kéna-Cohen
authors.forename: Richard R
authors.initials: RR
authors.lastname: Lunt
keywords: alkali metal halide salt; doping; hole extraction; hysteresis; iodide vacancies; passivation; perovskite photovoltaics