Phase diagrams and stability of lead-free halide double perovskites Cs2BB′X6: B = Sb and Bi, B′ = Cu, Ag, and Au, and X = Cl, Br, and I

Journal article

Lead-free pnictogen/noble metal halide double perovskites Cs 2 BiAgCl 6 , Cs 2 BiAgBr 6 , and Cs 2 SbAgCl 6 are some of the most promising environmentally friendly alternatives to lead-halide perovskites. However, due to their relatively large band gaps (1.9-2.2 eV), they are not yet competitive candidates for use in photovoltaic devices. In this work, we perform a systematic study of the thermodynamic stability of the entire family of Cs 2 BB′X 6 compounds (B = Bi and Sb, B′ = Cu, Ag, and Au, and X = Cl, Br, and I), and we explore the possibility of chemical mixing as a route to stabilize pnictogen/noble metal halide perovskites with low band gaps. Our calculations indicate that Cs 2 BiAg 1-x Cu x Cl 6 mixes should be amenable to synthesis and could reduce the band gap down to 1.6-1.9 eV.

Authors: Filip, M; Liu, X; Miglio, A; Hautier, G; Giustino, F

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Journal of Physical Chemistry C
• Volume: 122
• Issue: 1
• Pages: 158-170
• Publication date: 2017-11-28
• Acceptance date: 2017-11-28
• DOI: 10.1021/acs.jpcc.7b10370
• EISSN: 1932-7455
• ISSN: 1932-7447
• Keywords: lead-free perovskites; double halide perovskites; stability; phase diagrams