Halide Perovskites: Advanced Photovoltaic Materials Empowered by a Unique Bonding Mechanism

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 governed B?X bond, which is responsible for pronounced masses carriers. These frequently attributed to ns2 configuration B atom, i.e., Pb 6s2 Sn 5s2 (“lone-pair”) states. The analysis in conjunction with quantum-chemical bond reveals different scenario. differs significantly from ionic, metallic, conventional 2c?2e covalent bonds. Instead it better regarded as metavalent, since shares about one p-electron between adjacent atoms. resulting ?-bond, formally 2c?1e half-filled, causing absorption. Electron transfer atoms lattice distortions open moderate bandgap carriers Hence, metavalent bonding explains favorable halide perovskites, summarized map types, provides blueprint design