Improved photovoltaic performance of InGaN single junction solar cells by using n-on-p type device structure

摘要

The performance of In(0.65)Ga(0.35)N single junction solar cell including an InGaN window layer with p-on-n and n-on-p two types of configurations has been theoretically investigated. By taking polarization effects into consideration, it is found that with the same dislocation density the n-on-p type cell has a very high conversion efficiency, while the energy conversion efficiency of the conventional p-on-n type cell is very low. The superior performance of the n-on-p type cell is due to a better carrier collection efficiency resulting from an improved band alignment at the interface between the In(0.65)Ga(0.35)N emitter layer and the InGaN window layer, as compared to the n-on-p structure. The effects of dislocation density on the n-on-p type In(0.65)Ga(0.35)N solar cell efficiency have been evaluated and are compared with the case of the GaAs solar cell, showing that the InGaN solar cell has a greater tolerance level to the dislocation density than GaAs solar cell, which is very similar to the case for the light-emitting diodes.