La-doped CH3NH3BaI3: A promising transparent conductor La-doped CH3NH3BaI3: A promising transparent conductor
Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, Maharashtra, India
Adv. Mater. Lett., 2017, 8 (4), pp 342-345
Publication Date (Web): Mar 14, 2017
Copyright © IAAM-VBRI Press
Hybrid perovskites (CH3NH3PbI3) is one of the most promising novel materials for solar harvesting. Toxicity of lead (Pb), however, has always remained a concern. We investigated the electronic structure of complete replacement of Pb by alkaline earths (Ca, Sr, Ba) and found them to be wide band gap (Eg) semiconductors (band gap ~ 3.7 to 4.0 eV), and hence not suitable as absorber material. This opens up a new avenue to explore these materials as transparent conductor (TC). We doped CH3NH3BaI3 (largest Eg) with La, which shifts its Fermi level (EF) at conduction band bottom and induces states at EF for conduction. This is precisely what is required for a transparent conductors. Optical and transport properties simulated from linear response (within Density Functional Theory (DFT)) calculations suggested it to be a very good TC material with a high figure of merit (s/a), where s is the electrical conductivity and a is the optical absorption coefficient. This claim is also supported by our calculated results on density of states at EF, effective mass, carrier concentration etc. at various La-doping. We propose CH3NH3(Ba1-xLax)I3 (x£12.5%) to be a good TC material to be used in an all perovskite solar cell.
Solar cell, transparent conductor, hybrid perovskites, density functional theory.