CH3NH3CaI3 Perovskite: Synthesis, Characterization, and First-Principles Studies

In recent years, organo-lead-halide perovskites have emerged as promising new materials for photovoltaics, reaching high efficiencies. The excellent photoelectronic properties and easy solution processing makes the lead perovskite an ideal light harvesting material in a solar cell. In spite of these great advantages, there are concerns about the lead contained in the material because of its well-known toxicity characteristics. Obtaining new metal halide perovskites without lead is still a challenge; until now, only a few experimental reports have been published and some other theoretical calculations replacing lead by most of the possible candidates of the periodic table. In this paper, we show for the first time synthesis of the calcium hybrid perovskites CH3NH3CaI3 and CH3NH3CaI3–xClx with complementary studies based on first-principles band-structure calculation. Crystallographic analysis shows a pseudocubic structure, and optical measurements confirms that this type of perovskite absorbs light in the UV region, which is in good agreement with the calculation that showed a band gap larger than 3.5 eV.