  Due to their structured density of states, molecular junctions provide rich
resources to filter and control the flow of electrons and phonons. Here we
compute the out of equilibrium current-voltage characteristics and dissipated
heat of some recently synthesized oligophenylenes (OPE3) using the Density
Functional based Tight-Binding (DFTB) method within Non-Equilibrium Green's
Function Theory (NEGF). We analyze the Peltier cooling power for these
molecular junctions as function of a bias voltage and investigate the
parameters that lead to optimal cooling performance. In order to quantify the
attainable temperature reduction, an electro-thermal circuit model is
presented, in which the key electronic and thermal transport parameters enter.
Overall, our results demonstrate that the studied OPE3 devices are compatible
with temperature reductions of several K. Based on the results, some strategies
to enable high performance devices for cooling applications are briefly
discussed.
