Improved photovoltaic performance of quantum dot-sensitized solar cells using multi-layered semiconductors with the effect of a ZnSe passivation layer

摘要

Lead chalcogenide colloidal quantum dots (QDs) are potential candidates for applications effective in the near infrared spectral range. Photoanodes were sensitized with PbS/CdS/CdSe/ZnS and PbS/CdS/CdSe/ZnSe via a simple successive ion layer adsorption and reaction (SILAR) technique. In the present study, ZnSe was used as an alternative to ZnS. ZnSe was deposited on a TiO2/PbS/CdS/CdSe photoanode, which was more efficient in reducing electron recombination in the QDSSCs. The performance of the QDSSCs was scrutinized using a polysulfide electrolyte and a copper sulfide counter electrode. The PbS/CdS/CdSe/ZnSe electrode resulted in enhanced efficiency as compared to the PbS/CdS/CdSe/ZnS-sensitized QDs. Red shifts with PbS/CdS/CdSe/ZnSe were observed, which were attributed to the combined effect of QDs. This was confirmed via photovoltaic studies and electrochemical impedance spectroscopy. The PbS/CdS/CdSe/ZnSe electrode exhibits a short circuit current density of 17.53 mA cm(2) with an enhanced power to conversion efficiency (eta) of 4.15% under 1 Sun illumination (AM 1.5G, 100 mW cm(-2)).