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Speaker: Bin Hu, University of Tennessee
September 13, 2019 @ 11:00 am - 12:00 pm
Title: Orbit-Orbit Interaction Effects on Excited States in Hybrid Perovskites from 3D to 2D Design
Speaker: Bin Hu
Affiliation: University of Tennessee
Organic-inorganic hybrid perovskites are known as strong-orbital materials and have demonstrated unique photovoltaic, light-emitting, and lasing actions. The strong orbital momentum leads to an orbit-orbit interaction in excited states towards developing optoelectronic properties. In principle, the orbit-orbit interaction can directly affect both (i) Rashba effect associated with direct and indirect transitions and (ii) the interaction between excited states. Consequently, the orbit-orbit interaction provides a fundamental mechanism to control the light emission in both spontaneous and coherent regimes. Our recent studies found that the orbit-orbit interaction can be conveniently probed by using linearly and circularly polarized photoexcitations in magnetic field. More importantly, we observed in 3D perovskites that the orbit-orbit interaction can be largely changed by self-passivation of grain boundary defects. Essentially, the self-passivation of defects was induced to control the orbit-orbit interaction by the Coulomb interaction between oppositely charged defects on grain boundaries. This was realized by growing small grains on the surfaces of large grains by mixing two precursor solutions to introduce concurrently occurring fast and slow growth in in hybrid perovskites. As a result, efficient electroluminescence (EL) was demonstrated in perovskite LEDs. Furthermore, using orbit-orbit interaction can establish a cooperative interaction between light-emitting states to develop an amplified spontaneous emission (ASE) through orbital order. In 2D perovskites, we found that the orbit-orbit interaction can occur through short-range and long-range interactions occurring through magnetic electrical polarizations, consequently influencing light-emitting and photovoltaic actions. This presentation will discuss the underlying processes involved in the effects of orbit-orbit interaction on optoelectronic properties in organic-inorganic hybrid perovskites.
Dr. Bin Hu is a full professor in the department of materials science and engineering at the university of Tennessee. He received his Ph.D in condense matter physics in Chinese Academy of Sciences in 1991. After his postdoc in the department of polymer science and engineering at the University of Massachusetts (Amherst) and senior research scientist at SICPA Product Security Incorporation, Dr. Bin Hu joined University of Tennessee in 2002 as assistant professor, associate professor and then full professor. Dr. Bin Hu’s research interest includes spintronics, orbitronics, and photophysics in organic, organic-inorganic hybrid, and nanomaterials. Dr. Bin Hu received research achievement award multiple times at University of Tennessee. During his tenure-track period, he received NSF career development award. Dr. Bin Hu serves as editorial board member at Scientific Report, and associate editor at Journal of Photonics for Energy. He has published more than 160 papers in Nature Materials, Nature Communications, Advanced Materials, Advanced Energy Materials, Advanced Functional Materials, JACS, ACS Nano, Nano Energy, Small, JPCL, Scientific Report, etc.
We hope to see you there!