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UID:20250814T060857EDT-7299J6sFOo@132.216.98.100
DTSTAMP:20250814T100857Z
DESCRIPTION:Abstract:\n\nLead halide perovskites have been demonstrated as 
 high performance materials in solar cells and light-emitting devices. Thes
 e materials are characterized by coherent band transport expected from cry
 stalline semiconductors\, but dielectric responses and phonon dynamics typ
 ical of liquids. Here we explain the essential physics in this class of ma
 terials based on their dielectric functions and dynamic symmetry breaking 
 on nano scales. We show that the dielectric function in the THz region may
  lead to dynamic and local ordering of polar nano domains by an extra elec
 tron or hole\, resulting a quasiparticle which we call a ferroelectric lar
 ge polaron\, a concept similar to solvation in chemistry. Compared to a co
 nventional large polaron\, the collective nature of polarization in a ferr
 oelectric large polaron may give rise to order(s)-of-magnitude larger redu
 ction in the Coulomb potential. We suggest that the shape of a ferroelectr
 ic polaron resembles that of a Belgian waffle. The ferroelectric or Belgia
 n waffle polarons may explain the defect tolerance and low recombination r
 ates of charge carriers in lead halide perovskites\, as well as providing 
 a design principle of the “perfect” semiconductor for optoelectronics.\n\n
 Bio:\n\nXiaoyang Zhu is the Howard Family Professor of Nanoscience and a P
 rofessor of Chemistry at Columbia University. He received a BS degree from
  Fudan University in 1984 and a PhD from the University of Texas at Austin
  in 1989. After postdoctoral research with Gerhard Ertl at the Fritz-Haber
 -Institute\, he joined the faculty at Southern Illinois University as an A
 ssistant Professor in 1993. In 1997\, he moved to the University of Minnes
 ota as a tenured Associate Professor\, later a Full Professor\, and a Merc
 k endowed professor. In 2009\, he returned to the University of Texas at A
 ustin as the Vauquelin Regents Professor and Served as directors of the DO
 E Energy Frontier Research Center (EFRC) and the Center for Materials Chem
 istry. In 2013\, he moved to Columbia University. His honors include a Dre
 yfus New Faculty Award\, a Cottrell Scholar Award\, a Friedrich Wilhelm Be
 ssel Award\, APS Fellow\, a Vannevar Bush Faculty Fellow Award from DOD\, 
 and an Ahmed Zewail Award from the American Chemical Society. Among his pr
 ofessional activities\, he serves on the editorial/advisory boards of Scie
 nce Advances\, Chemical Physics\, and Progress in Surface Science\, and as
  a scientific advisor to Brookhaven National Laboratory and the Fritz-Habe
 r-Institute of the Max-Planck Society.\n
DTSTART:20200218T180000Z
DTEND:20200218T193000Z
LOCATION:Room 10\, Maass Chemistry Building\, CA\, QC\, Montreal\, H3A 0B8\
 , 801 rue Sherbrooke Ouest
SUMMARY:Chemical Society Seminar: Xiaoyang Zhu - Ferroelectric Polarons\, B
 elgian Waffles\, and Electron Solvation in Semiconductors
URL:/chemistry/channels/event/chemical-society-seminar
 -xiaoyang-zhu-ferroelectric-polarons-belgian-waffles-and-electron-solvatio
 n-303030
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