%0 Journal Article
%A Wuttig, Matthias
%A Schön, Carl-Friedrich
%A Schumacher, Mathias
%A Robertson, John
%A Golub, Pavlo
%A Bousquet, Eric
%A Gatti, Carlo
%A Raty, Jean-Yves
%T Halide Perovskites: Advanced Photovoltaic Materials Empowered by a Unique Bonding Mechanism
%J Advanced functional materials
%V 16
%N 2
%@ 1057-9257
%C Weinheim
%I Wiley-VCH
%M FZJ-2021-06174
%P 2110166 -
%D 2022
%X Outstanding photovoltaic (PV) materials combine a set of advantageous properties including large optical absorption and high charge carrier mobility, facilitated by small effective masses. Halide perovskites (ABX3, where X = I, Br, or Cl) are among the most promising PV materials. Their optoelectronic properties are governed by the BX bond, which is responsible for the pronounced optical absorption and the small effective masses of the charge carriers. These properties are frequently attributed to the ns2 configuration of the B atom, i.e., Pb 6s2 or Sn 5s2 (“lone-pair”) states. The analysis of the PV properties in conjunction with a quantum-chemical bond analysis reveals a different scenario. The BX bond differs significantly from ionic, metallic, or conventional 2c2e covalent bonds. Instead it is better regarded as metavalent, since it shares about one p-electron between adjacent atoms. The resulting σ-bond, formally a 2c1e bond, is half-filled, causing pronounced optical absorption. Electron transfer between B and X atoms and lattice distortions open a moderate bandgap resulting in charge carriers with small effective masses. Hence, metavalent bonding explains favorable PV properties of halide perovskites, as summarized in a map for different bond types, which provides a blueprint to design PV materials.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000710103100001
%R 10.1002/adfm.202110166
%U https://juser.fz-juelich.de/record/904604