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Ionically Generated Built‐In Equilibrium Space Charge Zones—a Paradigm Change for Lead Halide Perovskite Interfaces
Author(s) -
Kim Gee Yeong,
Senocrate Alessandro,
Moia Davide,
Maier Joachim
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202002426
Subject(s) - photovoltaics , materials science , perovskite (structure) , chemical physics , ionic bonding , space charge , redistribution (election) , halide , photovoltaic system , charge carrier , ion , solar cell , mesoporous material , perovskite solar cell , nanotechnology , engineering physics , optoelectronics , physics , inorganic chemistry , chemical engineering , chemistry , electrical engineering , quantum mechanics , biochemistry , catalysis , politics , political science , law , engineering , electron
Methylammonium lead iodide (MAPI) is the archetype of the intensively researched class of perovskites for photovoltaics. Nonetheless, even equilibrium aspects are far from being fully understood. Equilibrium space charge effects at the MAPI/TiO 2 and MAPI/Al 2 O 3 interfaces are discussed, which are of paramount significance for solar cells. Different from the photovoltaic literature in which such built‐in potentials are considered as being generated solely by electronic charge carriers, a generalized picture that considers the equilibrium distribution of both ionic and electronic carriers is applied. Experimental evidence is given that shows it is the ions that are responsible for the equilibrium space charge potential, the reason being a pronounced ion adsorption at the contacts. The electronic redistribution is a sheer consequence of the so‐established electric field. Experiments with mesoporous oxide as well as experiments with MAPbBr 3 (MAPBr) indicate photovoltaic relevance and material generality in terms of the choice of the lead‐based perovskite. The occurrence of space charge effects at heterojunctions generated by ionic redistribution is not only a novel concept in photovoltaics, it also provides a new path to modifying charge‐selective interfaces, as well as a better understanding of the behavior in mesoporous systems.