Mixed Valence Perovskite Cs2Au2I6: A Potential Material for Thin‐Film Pb‐Free Photovoltaic Cells with Ultrahigh Efficiency |
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| Authors: | Lamjed Debbichi Songju Lee Hyunyoung Cho Andrew M. Rappe Ki‐Ha Hong Min Seok Jang Hyungjun Kim |
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| Affiliation: | 1. Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Yuseong‐Gu, Daejeon, Korea;2. School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Yuseong‐Gu, Daejeon, Korea;3. Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA;4. Department of Materials Science and Engineering, Hanbat National University, Yuseong‐Gu, Daejeon, Korea;5. Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Yuseong‐Gu, Daejeon, Korea |
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| Abstract: | New light is shed on the previously known perovskite material, Cs2Au2I6, as a potential active material for high‐efficiency thin‐film Pb‐free photovoltaic cells. First‐principles calculations demonstrate that Cs2Au2I6 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 Cs2Au2I6 a double‐perovskite material, although it is stoichiometrically a single perovskite. In contrast to most previously discussed double perovskites, Cs2Au2I6 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 Cs2Au2I6 will serve as the active material in highly efficient, nontoxic, and thin‐film perovskite solar cells in the very near future. |
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| Keywords: | first‐principles calculations lead‐free perovskite solar cells mixed valency multiscale simulations thin film solar cells |
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