Ultrafast Carrier Dynamics of Dual Emissions from Methylammonium Lead Iodide Perovskites

Hybrid lead iodide perovskites have been attractive for its optical properties for many applications in different fields. One of the most promising applications is as a material for future generation of solar cells. The understanding of the photoexcitation dynamics is very important for improving their performance in solar cells and other applications. We implemented optical two-dimensional coherent spectroscopy to study the carrier dynamics and coupling of dual emissions in Methylammonium Lead Iodide film at 115 K. The sample was prepared by spin-coating perovskite precursor onto a glass substrate and successive annealing at 100 °C. From the 2D spectra we observed an ultrafast redistribution of the photoexcited carriers into the two emission resonances. The dynamics of carrier relaxation into the high energy and low energy resonance are different. The high-energy resonance is a short-lived transient state. The low-energy resonance has a longer lifetime and interacts with coherent phonons.