  We introduce a quantum dot orbital tight-binding non-equilibrium Green's
function approach for the simulation of novel solar cell devices where both
absorption and conduction are mediated by quantum dot states. By the use of
basis states localized on the quantum dots, the computational real space mesh
of the Green's function is coarse-grained from atomic resolution to the quantum
dot spacing, which enables the simulation of extended devices consisting of
many quantum dot layers.
