Enhanced optical properties and dark I-V characteristics of silicon nanowire-carbon quantum dots heterostructures

Herein, we report a silicon nanowire (SiNW) array-carbon quantum dot (CQD) heterostructure photovoltaic device via direct coating of CQD on chemically-etched SiNW arrays aided by Ag. By using carbon quantum dots layer as a competent element for surface passivation and modification for SiNWs, the solar cells efficiency is improved. The 1.6 times absorption enhancement has been recorded for nitrogen doped CQD decorated pyramidal SiNW heterostructure in comparison to that of CQDs coated silicon nanowires on the planar surfaces. Inclusion of nitrogen doped CQDs into the pyramidal SiNW arrays gives enhanced absorption intensity which can act as a good absorber layer in solar cell. The heterostructure also displays a significant photoluminescence in the blue region as probed by using time-resolved photoluminescence (TRPL) technique which provide the insight into the recombination mechanism in the synthesized heterostructures and is discussed in detail.