  Low-dimensional electronic and glassy phononic transport are two important
ingredients of highly-efficient thermoelectric material, from which two
branches of the thermoelectric research emerge. One focuses on controlling
electronic transport in the low dimension, while the other on multiscale phonon
engineering in the bulk. Recent work has benefited much from combining these
two approaches, e.g., phonon engineering in low-dimensional materials. Here, we
propose to employ the low-dimensional electronic structure in bulk phonon-glass
crystal as an alternative way to increase the thermoelectric efficiency.
Through first-principles electronic structure calculation and classical
molecular dynamics simulation, we show that the $\pi$-$\pi$ stacking
Bis-Dithienothiophene molecular crystal is a natural candidate for such an
approach. This is determined by the nature of its chemical bonding. Without any
optimization of the material parameter, we obtain a maximum room-temperature
figure of merit, $ZT$, of $1.48$ at optimal doping, thus validating our idea.
