Superlattice intermediate band solar cell with resonant upper-conduction-band assisted photo-absorption and carrier extraction

Drift-diffusion modeling of a superlattice p-i-n device with resonant conduction-band assisted photon absorption and carrier

“…The new conduction sub-bands originated by such a splitting due to the N induced perturbation are denoted as E_ and E+ [9], An example of material composition selection in AlGaAs/GaAsN system is shown in AlGaAs/GaAsN system is shown in Figure 2. To assess the photovoltaic potential of the proposed design we have undertaken a detailed balance modeling of by assuming a device incorporating a 0.5 microns superlattice region with the intermediate band region absorption properties comparable to the one calculated in Fig 3. The preliminary calculation presented here assumes that all photons with energy larger than the bandgap of AlGaAs (or E+) are be absorbed in the emitter of the device (thick emitter approximation) whereas photons with energy comprised between the fundamental miniband state and resonant E+ level are absorbed with an absorption properties similar to that of the dilute nitride superlattice [10,11]. Since here the intersubband absorption between the fundamental or excited states (intermediate 2D band) and to the upper conduction band and involves 3D like E+ states of the dilute nitride material/AlGaAs, the oscillator strength =0 selection rule under normal illumination does not limit the absorption as it is the case for conventional superlattices.…”