Fabrication of quantum dot-sensitized solar cells with multilayer TiO_2/PbS(X)/CdS/CdSe/ZnS/SiO_2 photoanode and optimization of the PbS nanocrystalline layer

摘要

In this work, two multilayer photoanode structures of TiO_2/PbS(X)/CdS/ZnS/ SiO_2 and TiO_2/PbS(X)/CdS/CdSe/ZnS/SiO_2 were fabricated and applied in quantum dot-sensitized solar cells (QDSCs). Then, the effect of PbS QDs layer on the photovoltaic performance of corresponding cells was investigated. The sen-sitization was carried out by PbS and CdS QDs layers deposited on TiO_2 scaffold through successive ionic layer adsorption and reaction (SILAR) method. The CdSe QDs film was also formed by a fast, modified chemical bath deposition (CBD) approach. Two passivating ZnS and SiO_2 layers were finally deposited by SILAR and CBD methods, respectively. It was shown that the reference cell with TiO_2/ CdS/ZnS/SiO_2 photoanode demonstrated a power conversion efficiency (PCE) of 3.0%. This efficiency was increased to 4.0% for the QDSC with TiO_2/PbS(2)/CdS/ ZnS/SiO_2 photoelectrode. This was due to the co-absorption of incident light by low-bandgap PbS nanocrystalline film and also the CdS QDs layer and well transport of the charge carriers. For the CdSe included QDSCs, the PbS-free reference cell represented a PCE of 4.1 %. This efficiency was improved to 5.1 % for the optimized cell with TiO_2/PbS(2)/CdS/CdSe/ZnS/SiO_2 photoelectrode. The maximized efficiency was enhanced about 25% and 70% compared to the PbS-free reference cells with and without the CdSe QDs layer.