(Invited) Photovoltaic Aspects of Organic Lead Halide Perovskites

Organic lead halide perovskites have gained a lot of attention in recent months because of their photovoltaic property. Varying the composition of Br- and Cl- in such perovskites allows us to tune the bandgap of these materials. Crystallization kinetics can be tailored to yield improved thin film homogeneity by simply tuning the composition of halides in the precursor solution. Formation of methyl ammonium lead halide in films prepared from mixed halide systems is dictated by the complexation equilibrium between Pb2+ and Br-, and Pb2+ and I-. The excited state characterization offers a convenient way to probe the evolution of perovskite structure from lead halide complex. Spectroscopic and structural characterization techniques shed light on the thermally-driven evolution of the perovskite structure in mixed halide systems.