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 pyra-midal 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.

Automated summary

In this study, a silicon nanowire-carbon quantum dot heterostructure photovoltaic device was developed by directly coating carbon quantum dots on chemically-etched silicon nanowire arrays. The efficiency of the solar cells was improved by using carbon quantum dots as a surface passivation and modification element for the silicon nanowires. A 1.6 times absorption enhancement was observed for the nitrogen doped carbon quantum dot decorated pyramidal silicon nanowire heterostructure compared to carbon quantum dots coated silicon nanowires on planar surfaces. The inclusion of nitrogen doped carbon quantum dots into the pyramidal silicon nanowire arrays provided enhanced absorption intensity, making them a good absorber layer in solar cells. The heterostructure also exhibited significant photoluminescence in the blue region, allowing insight into the recombination mechanism.