Limiting efficiency of silicon based nanostructure solar cells for multiple exciton generation

Abstract

The materials for multiple exciton generation (MEG) solar cells have often focused on colloidal systems using low band gap materials such as PbSe. However, detailed balance calculations with non-ideal quantum yield (QYs) lead to higher band gaps, with silicon close to the optimum value. We calculate the conversion efficiency of MEG processes including non-idealities for nanostructured silicon. We also boost efficiency of MEG solar cells using multijunction solar cell configurations. Incorporating MEG into multijunction solar cells leads to increased calculated efficiencies due to QYs greater than unity in each junction. Here we have simulated the possible MEG enhanced QY of each junction and the corresponding conversion efficiencies for double junction hybrid solar cells. This hybrid structure extends the opportunities to maximize the MEG effect and also to select the appropriate effective bandgaps using silicon nanostructures.