Despite their compositional versatility, most halide double perovskites feature large band gaps. Herein, we describe a strategy for achieving small band gaps in this family of materials. The new double perovskites Cs2AgTlX6(X=Cl (
- Award ID(s):
- 1809756
- NSF-PAR ID:
- 10336978
- Date Published:
- Journal Name:
- Materials Advances
- Volume:
- 1
- Issue:
- 8
- ISSN:
- 2633-5409
- Page Range / eLocation ID:
- 2840 to 2845
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract 1 ) and Br (2 )) have direct band gaps of 2.0 and 0.95 eV, respectively, which are approximately 1 eV lower than those of analogous perovskites. To our knowledge, compound2 displays the lowest band gap for any known halide perovskite. Unlike in AIBIIX3perovskites, the band‐gap transition in AI2BB′X6double perovskites can show substantial metal‐to‐metal charge‐transfer character. This band‐edge orbital composition is used to achieve small band gaps through the selection of energetically aligned B‐ and B′‐site metal frontier orbitals. Calculations reveal a shallow, symmetry‐forbidden region at the band edges for1 , which results in long (μs) microwave conductivity lifetimes. We further describe a facile self‐doping reaction in2 through Br2loss at ambient conditions. -
Abstract Despite their compositional versatility, most halide double perovskites feature large band gaps. Herein, we describe a strategy for achieving small band gaps in this family of materials. The new double perovskites Cs2AgTlX6(X=Cl (
1 ) and Br (2 )) have direct band gaps of 2.0 and 0.95 eV, respectively, which are approximately 1 eV lower than those of analogous perovskites. To our knowledge, compound2 displays the lowest band gap for any known halide perovskite. Unlike in AIBIIX3perovskites, the band‐gap transition in AI2BB′X6double perovskites can show substantial metal‐to‐metal charge‐transfer character. This band‐edge orbital composition is used to achieve small band gaps through the selection of energetically aligned B‐ and B′‐site metal frontier orbitals. Calculations reveal a shallow, symmetry‐forbidden region at the band edges for1 , which results in long (μs) microwave conductivity lifetimes. We further describe a facile self‐doping reaction in2 through Br2loss at ambient conditions. -
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