Link between hopping models and percolation scaling laws for charge transport in mixtures of small molecules
Author(s)Kim, Jang-Joo; Ha, Dong-Gwang; Baldo, Marc A
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Mixed host compositions that combine charge transport materials with luminescent dyes offer superior control over exciton formation and charge transport in organic light emitting devices (OLEDs). Two approaches are typically used to optimize the fraction of charge transport materials in a mixed host composition: either an empirical percolative model, or a hopping transport model. We show that these two commonly-employed models are linked by an analytic expression which relates the localization length to the percolation threshold and critical exponent. The relation is confirmed both numerically and experimentally through measurements of the relative conductivity of Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) :1,3-bis(3,5-dipyrid-3-yl-phenyl)benzene (BmPyPb) mixtures with different concentrations, where the TCTA plays a role as hole conductor and the BmPyPb as hole insulator. The analytic relation may allow the rational design of mixed layers of small molecules for high-performance OLEDs.
DepartmentMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Department of Materials Science and Engineering
American Institute of Physics (AIP)
Ha, Dong-Gwang, Jang-Joo Kim, Marc A. Baldo. “Link Between Hopping Models and Percolation Scaling Laws for Charge Transport in Mixtures of Small Molecules.” AIP Advances 6, 4 (April 2016): 045221 © 2016 Author(s)
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