1. Tuning the Optical Absorption of Sn-, Ge-, and Zn-Substituted Cs2AgBiBr6 Double Perovskites: Structural and Electronic Effects
- Author
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Paz Sebastia-Luna, Michele Sessolo, Henk J. Bolink, Nicolás Albiach-Sebastián, Joaquín Calbo, Francisco Palazon, and Enrique Ortí
- Subjects
Materials science ,General Chemical Engineering ,Materials Chemistry ,Electronic effect ,Analytical chemistry ,Double perovskite ,General Chemistry ,Absorption (electromagnetic radiation) ,Materials ,Cèl·lules fotoelèctriques - Abstract
Lead-free halide double perovskites (DPs) are highly tunable materials in terms of chemical composition and optical properties. One of the most widely reported DPs is Cs2AgBiBr6, which is envisaged as a promising absorber for photovoltaics. Nevertheless, its bandgap (around 1.9−2.3 eV) remains too large for common tandem solar cells. In this work, we report the mechanochemical synthesis of Sn-, Ge-, and Zn-substituted Cs2AgBiBr6 in powder form; their bandgaps reach 1.55, 1.80, and 2.02 eV, respectively. These differences are rationalized through density functional theory calculations, demonstrating combined electronic and structural (disorder) effects introduced by the divalent metal-cation substituents. Finally, we present the first vacuum-deposited thin films of the Sn-substituted DP, which also show a notable narrowing of the bandgap, and this paves the way toward its implementation in photovoltaic solar cells.
- Published
- 2021
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