This thesis aims to present a full-band description for the modeling and simulation of optoelectronic devices. To do this, the nonequilibrium Green's function (NEGF) formalism is used to accurately describe the quantum processes affecting carrier dynamics within the device, everything coupled through a self-consistent (SC) loop which is iterated to achieve the correct device properties under the given input conditions. Simulation of nanoscale devices should take into account several quantum processes that dominate the device behavior at these dimensions. Consequently, quantum models have acquired such a great importance nowadays in the modeling of microelectronic and optoelectronic devices, specially in the case of LED's and solar cells, whose many problems arising from the low efficiency and losses make it imperative to understand what are the real phenomena behind them.