posted on 2018-12-10, 00:00authored byNa’im Kalantar, Dvira Segal
Understanding
excitation and charge transfer in disordered media
is a significant challenge in chemistry, biophysics, and material
science. We study two experimentally relevant measures for carrier
transfer in finite-size chains, a mean first-passage time (MFPT) and
the steady-state transfer time (SSTT). We discuss the relationship
between these measures and derive analytic formulas for 1D chains.
We exemplify the behavior of these time scales in different motifs:
donor–bridge–acceptor systems, biased chains, and alternating
and stacked copolymers. We find that the MFPT and the SSTT may administer
different, complementary information on the system, jointly reporting
on molecular length and energetics. Under constraints such as fixed
donor–acceptor energy bias, we show that the MFPT and the SSTT
are optimized (minimized) under fundamentally different internal potential
profiles. This study brings insights into the behavior of the MFPT
and the SSTT and suggests that it is beneficial to perform both transient
and steady-state measurements on a conducing network so as to gather
a more complete picture of its properties.