MSE Seminar: Reduced Dimensional Solution-Processed Energy Materials
Speaker: Li Na Quan, University of California Berkeley
Title: Reduced Dimensional Solution-Processed Energy Materials
Metal halide perovskites are promising solution-processed materials for use in photovoltaics and light emitting diodes (LEDs) in view of their excellent semiconducting properties, the broad spectral range of light absorption, and narrow bandwidth emission. In this talk, I will present how we use the low dimensional perovskite to increase material stability, concentrate charge, improve light emission property, and create optical sources. I will discuss the approaches to improve the stability of the materials, light emitting properties and device performance by tuning the dimensionality and create the mixed-perovskite material with tunable electronic bandgap. At an applied level, I will demonstrate how we achieve the perovskite materials that exhibit near-perfect passivation, with their photoluminescence quantum yields closely approaching unity. They are bright, stable, efficient and easily solution-processible, which renders them useful for light emitting applications. These materials can also be a good platform to design and synthesis of the infra-red (IR) emitting materials and devices. Beyond the material development, I will describe how the electronic excitation of the materials are couple to the lattice vibration and deformation using advanced time-resolved spectroscopy. The unique soft nature of the perovskite lattice gives rise to dynamic fluctuations in the electronic bandgap, which distinguishes hybrid perovskites from traditional inorganic semiconductors.