Numerical simulation and modeling of spectral conversion by silicon nanocrystals with multiple exciton generation

Silicon nanocrystals (Si-NCs) were applied on the front surface of a conventional silicon solar cell. Considering absorption with multiple exciton generation (MEG) yields and consequently photoluminescence, the cell performance was simulated based on a numerical model founded on experimental results in literature. The results show that the cell efficiency could be prominently enhanced by MEG yields and spectral down-conversion. However, though MEG yields could reach 250% within Si-NCs, it only contributes 8.7% to the cell efficiency enhancement while wavelength shifting dominates the cell efficiency enhancement mechanism. Additionally, extraction factor which is defined as ratio of photons extracted from Si-NCs to the generated carries in Si-NCs is the most critical parameter for cell performance improvement. Therefore, to realize this novel structure cell, further experimental work should be lay on improving MEG efficiency as well as photoluminescence efficiency and optical confinement of the photoluminescence. (C) 2011 American Institute of Physics. [doi:10.1063/1.3549697]