Halogen in materials design: Chloroammonium lead triiodide perovskite (ClNH3 PbI3 ) a dynamical bandgap semiconductor in 3D for photovoltaics.

Abstract

Methylammonium lead trihalides and their derivatives are photovoltaic materials. CH3 NH3 PbI3 is the most efficient light harvester among all the known halide perovskites (PSCs). It is regarded as unsuitable for long-term stable solar cells, thus it is necessary to develop other types of PSC materials to achieve stable PSCs (Wang et al., Nat. Energy 2016, 2, 16195). Because of this, various research efforts are on-going to discover novel lead-based or lead-free single/double PSCs, which can be stable, synthesizable, transportable, abundant and efficient in solar energy conversion. Keeping these factors in mind, we report here the electronic structures, energetic stabilities and some materials properties (viz. band structures, density of states spectra and photo-carrier masses) of the PSC chloroammonium lead triiodide (ClNH3 PbI3 ). This emerges through compositional engineering that often focuses on B- and Y-site substitutions within the domain of the BMY3 PSC stoichiometry. ClNH3 PbI3 is found to be stable as orthorhombic and pseudocubic polymorphs, which are analogous with the low and high temperature polymorphs of CH3 NH3 PbI3 . The bandgap of ClNH3 PbI3 (values between 1.28 and 1.60 eV) is found to be comparable with that of CH3 NH3 PbI3 , (1.58 eV), both obtained with periodic DFT at the PBE level of theory. Spin orbit coupling is shown to have a pronounced effect on both the magnitude and character of the bandgap. The computed results show that ClNH3 PbI3 may act as a competitor for CH3 NH3 PbI3 for photovoltaics. © 2018 Wiley Periodicals, Inc.