Excitonic optical properties of CH3NH3PbI3 perovskite and its dependence with temperature

Methylammonium lead iodide perovskites have a lot of potential for the development of new photovoltaic and light emitting devices. But many of their optical properties have yet to be understood. In this work, the absorption and photoluminescence properties of Methylammonium lead iodide were studied as a function of temperature. A strong excitonic absorption, modeled with Elliott formula was observed and allowed to calculate an absorption edge whose energy increases as the temperature increases with a 100 meV reduction in a phase transition at 125 K. An exciton binding energy that shifts from 20 to 32 meV as the temperature increases was also calculated. The Photoluminescence shows a strong and sharp peak that was inhibited by a second wider peak in the low temperature phase. The first one was attributed to free exciton recombination and the second one to localized exciton recombination.