Abstract:

Excited electronic states have played a critical role in the operation of many of our transformative technologies including in displays, photodetectors, and solar cells and will likely be foundational to future quantum devices. Surprisingly, our ability to manipulate and control excited states is still in its infancy, as most carriers rapidly lose energy and coherence as they inefficiently transport through materials. The goals of my research have been to develop an in depth understanding of the fundamental loss mechanisms which limit efficient energy flow and information transfer in nanostructured materials. In this talk, I will discuss the first visualization defect-dominated charge carrier recombination and transport in polycrystalline perovskite semiconductors. Next, I will show passivation strategies I developed to selectively target these defective regions on the nanoscale, leading to new benchmarks in quasi-Fermi level splitting (i.e. voltage), charge carrier lifetime, and photovoltaic device performance. Lastly, I will discuss my work in controlling the relaxation of strongly-coupled states of light and matter, exciton-polaritons, towards the formation of room-temperature Bose-Einstein condensates. These studies have uncovered new and exciting directions in engineering the photochemical, electronic, and magnetic properties of materials that are needed to build  the next generation of optoelectronic and quantum technologies.

Bio: 

Dr. Dane W. deQuilettes is the Chief Science Officer and Cofounder of Optigon, an MIT spinout building multimodal metrology tools for automated materials characterization. Previously, he was a Principal Investigator and member of the Technical Staff at MIT Lincoln Laboratory in the Quantum Information and Integrated Nanosystems Group. Prior to Lincoln Lab, he held a postdoctoral position at MIT in the group of Vladimir Bulovic, where he led a team in achieving the longest charge carrier lifetime ever measured in a direct bandgap semiconductor through the chemical design of surface fields. In 2017, he received his Ph.D in Chemistry and Nanotechnology from the University of Washington working in David Ginger’s group as a NSF Graduate Research and Clean Energy Institute Fellow. During his graduate studies, he was the first to discover the location of defects in polycrystalline metal halide perovskite semiconductors and he subsequently developed some of the first passivation strategies that have since been used to set world records in perovskite LED efficiency as well as photovoltaic power conversion efficiency. He has been named 1 of the 11 “Rising Stars” in the Natural Sciences by Nature Index, awarded the IUPAC-Solvay International Award for Young Chemists, and was listed to Forbes 30 under 30 in Energy for his work in developing new materials for solar energy conversion.