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Finite-Temperature TD-DMRG for the Carrier Mobility of Organic Semiconductors
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posted on 2020-07-02, 14:50 authored by Weitang Li, Jiajun Ren, Zhigang ShuaiA large
number of nonadiabatic dynamical studies have been applied
to reveal the nature of carrier transport in organic semiconductors
with different approximations. We present here a “nearly exact”
graphical-process-unit-based finite-temperature time-dependent density
matrix renormalization group (TD-DMRG) method to evaluate the carrier
mobility in organic semiconductors, as described by the electron–phonon
model, in particular, in rubrene crystal, one of the prototypical
organic semiconductors, with parameters derived from first-principles.
We find that (i) TD-DMRG is a general and robust method that can bridge
the gap between hopping and band pictures, covering a wide range of
electronic coupling strengths and (ii) with realistic parameters,
TD-DMRG is able to account for the experimentally observed “band-like”
transport behavior (∂μ/∂T < 0) in rubrene. We further study the long-standing puzzle of
the isotope effect for charge transport and unambiguously demonstrate
that the negative isotope effect (∂μ/∂m < 0 where m is the
atomic mass) should be universal.