TY  - JOUR
AU  - Wuttig, Matthias
AU  - Schön, Carl-Friedrich
AU  - Schumacher, Mathias
AU  - Robertson, John
AU  - Golub, Pavlo
AU  - Bousquet, Eric
AU  - Gatti, Carlo
AU  - Raty, Jean-Yves
TI  - Halide Perovskites: Advanced Photovoltaic Materials Empowered by a Unique Bonding Mechanism
JO  - Advanced functional materials
VL  - 16
IS  - 2
SN  - 1057-9257
CY  - Weinheim
PB  - Wiley-VCH
M1  - FZJ-2021-06174
SP  - 2110166 -
PY  - 2022
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000710103100001
DO  - DOI:10.1002/adfm.202110166
UR  - https://juser.fz-juelich.de/record/904604
ER  -