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DTSTART;TZID=America/Los_Angeles:20211021T160000
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DTSTAMP:20260617T100130
CREATED:20210816T220310Z
LAST-MODIFIED:20210816T220310Z
UID:13526-1634832000-1634832000@www.chemistry.ucla.edu
SUMMARY:Understanding and Exploiting Redox in Conjugated Polymers: From Improved Polymer Conductivity\, to Photoinduced Charge Transfer\, to Next Generation Polymer Binders for Lithium Ion Batteries
DESCRIPTION:Semiconducting polymer have the potential to be use in an exciting array of devices\, but their intrinsic conductivity is \nlow due to their large band gaps. Chemically doping conjugated polymers is an effective way to increase conductivity \nand involves introducing treating the polymer with a strong electron acceptor or donor that can undergo charge \ntransfer (i.e. redox) with the polymer. The charge transfer reaction creates delocalized electrical carriers on the \npolymer chain (usually positive polarons a.k.a. holes) while the dopant molecules remain in the film and serves as a \ncounterion. Unfortunately\, strong electrostatic attraction between counter-ions and most dopants will localize the \npolarons and reduce their mobility. Here\, we first explore a new family dopants based on substituted icosahedral \ndodecaborane (DDB) clusters that provide a unique combination of high oxidizing potential and large size. By tuning \nthe cluster redox potential\, we can understand the role of energetics in polymer conductivity\, and the large size helps \nreduce electrostatic interactions\, resulting in polymer films with highly delocalized polarons and thus high \nconductivity. A combination of molecular substituent tuning\, electronic spectroscopy\, and X-ray scattering are used \nto under chemical-structure-function relationships. We next consider applications for doped conjugated polymers\, in \nthis case focusing on electrochemically doped polymers and their application as binders in lithium ion batteries. \nBattery binders are usually chosen only for chemical inertness\, but the use of conjugated polymer binder can \nincrease overall conductivity and thus rate capabilities. By tuning the polymer redox to match the electrode material\, \nhighly conductive doped binders can be produced\, and by tuning the side chains\, ionic conductivity can be mixed with \nelectronic conductivity\, both of which are needed for fast battery operation. Finally\, we end by examining self- \nassembling amphiphilic conjugated polymers\, and consider both photo-doping and chemical doping of these unique \nwater soluble polymers.
URL:https://www.chemistry.ucla.edu/seminars/tba-11/
CATEGORIES:Organic Colloquium,Seminars
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