Influence of the inverse Auger process on the performance of InxGa1−xN/GaN quantum dot solar cells

It has been proposed that the use of self-assembled nano sized quantum dot (QD) arrays can break the Shockley–Queisser efficiency limit by extending the absorption of solar cells into the low-energy photon range while preserving their output voltage. This would be possible if the infrared photons are absorbed in the two sub-bandgap QD transitions simultaneously and the energy of two photons is added up to produce one single electron–hole pair, as described by the intermediate band model. This paper indicates the energy conversion efficiency of a quantum dot multilayer solar cell considering impact ionization effect. A p–i–n InxGa1−xN/GaN quantum dot solar cell structure has been taken into account in the calculation. It is shown that the efficiency of a cell strongly depends on the impact ionization in stacked quantum dots at i-region of the cell. In our proposed structure it is demonstrated that, if averaged probability of impact ionization, P, varies from zero to one, maximum efficiency increases by more than 12% (from 43 percent in P = 0 to 55 percent in P = 1). Also it is demonstrated that by decreasing θ, maximum efficiency increases and reaches to its maximum, 59%, in θ = 2.