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Mixed Valence Perovskite Cs 2 Au 2 I 6 : A Potential Material for Thin‐Film Pb‐Free Photovoltaic Cells with Ultrahigh Efficiency
Author(s) -
Debbichi Lamjed,
Lee Songju,
Cho Hyunyoung,
Rappe Andrew M.,
Hong KiHa,
Jang Min Seok,
Kim Hyungjun
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201707001
Subject(s) - materials science , perovskite (structure) , band gap , thin film , active layer , crystallite , optoelectronics , photovoltaic system , energy conversion efficiency , valence (chemistry) , layer (electronics) , nanotechnology , crystallography , ecology , chemistry , metallurgy , biology , thin film transistor , physics , quantum mechanics
New light is shed on the previously known perovskite material, Cs 2 Au 2 I 6 , as a potential active material for high‐efficiency thin‐film Pb‐free photovoltaic cells. First‐principles calculations demonstrate that Cs 2 Au 2 I 6 has an optimal band gap that is close to the Shockley–Queisser value. The band gap size is governed by intermediate band formation. Charge disproportionation on Au makes Cs 2 Au 2 I 6 a double‐perovskite material, although it is stoichiometrically a single perovskite. In contrast to most previously discussed double perovskites, Cs 2 Au 2 I 6 has a direct‐band‐gap feature, and optical simulation predicts that a very thin layer of active material is sufficient to achieve a high photoconversion efficiency using a polycrystalline film layer. The already confirmed synthesizability of this material, coupled with the state‐of‐the‐art multiscale simulations connecting from the material to the device, strongly suggests that Cs 2 Au 2 I 6 will serve as the active material in highly efficient, nontoxic, and thin‐film perovskite solar cells in the very near future.