Correlating Molecular Structures with Transport Dynamics
in High-Efficiency Small-Molecule Organic Photovoltaics
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Abstract
Efficient charge transport is a key
step toward high efficiency
in small-molecule organic photovoltaics. Here we applied time-of-flight
and organic field-effect transistor to complementarily study the influences
of molecular structure, trap states, and molecular orientation on
charge transport of small-molecule DRCN7T (D1) and its analogue DERHD7T
(D2). It is revealed that, despite the subtle difference of the chemical
structures, D1 exhibits higher charge mobility, the absence of shallow
traps, and better photosensitivity than D2. Moreover, charge transport
is favored in the out-of-plane structure within D1-based organic solar
cells, while D2 prefers in-plane charge transport