Events
Elucidating the Complex Recombination Kinetics in Organic-Inorganic Trihalide Perovskites*
December 8, 2015 at 4:30pm/36-428
Dane de Quilettes
University of Washington
Solution processed semiconductors are often plagued by performance limiting defects, surprisingly organometal trihalide perovskites (e.g. CH3NH3PbI3) have exhibited excellent photovoltaic power conversion efficiencies comparable to meticulously refined commercial solar materials. We have recently used confocal photoluminescence (PL) microscopy and fluorescence lifetime imaging microscopy (FLIM) to reveal significant local heterogeneity in non-radiative recombination rates in polycrystalline perovskite thin films. Showing that although these materials have a seemingly high defect tolerance, they still possess many imperfections at surfaces and grain boundaries that detrimentally affect carrier mobility and lifetime. Here I will highlight a selection of compounds with the potential to further reduce non-radiative recombination in perovskite films, and quantify the effects on local trap state density using kinetic models. Using picosecond PL spectroscopy, I will further discuss how processing and treatments can affect the various kinetic pathways that carriers traverse before repopulation of the ground state. This seminar will emphasize the nature of non-radiative loss at the surfaces of perovskite films and point the way for further improvements in these materials for light emitting and solar cell applications.
Dane de Quilettes is a National Science Foundation Graduate Research and Clean Energy Institute Fellow at the University of Washington pursuing a dual title Ph.D. degree in Chemistry and Nanotechnology. He graduated magna cum laude from Pepperdine University in 2012 with a B.S. in Chemistry and minor in Applied Mathematics. He is primarily interested in understanding the energetic landscape excited carriers traverse upon light absorption in next generation solar materials and controlling carrier relaxation dynamics through various chemical modifications.
*This talk is part of the Perovskites Seminar Series organized by Sam Stranks and sponsored by the Center for Excitonics. For more info contact Sam Stranks: stranks@mit.edu
