|
چکیده
|
In this research, two novel multi-layer photoelectrodes were fabricated and applied in quantum dot sensitized solar cells (QDSCs). The double layer scaffolds were composed of a TiO2 nanocrystalline sub-layer covered with an over-grown TiO2 nanorods (NRs) or ex-synthesized TiO2 hollow spheres (HSs) film. The light sensitization was carried out by deposition of separated PbS, CdS and CdSe quantum dots (QDs) layers. Finally, two electron blocking/passivating films of ZnS and SiO2 were formed for better photovoltaic (PV) performance. The syntheses of TiO2 nanocrystals (NCs), HSs and NRs were performed and tuned through different hydrothermal methods. The depositions of the PbS, CdS and ZnS layers were carried out by conventional successive ionic layer adsorption and reaction (SILAR) process. The CdSe and SiO2 films were also formed using a modified, effective chemical bath deposition (CBD) and sol–gel techniques, respectively. The PbS sensitizing film was additionally utilized for higher PV efficiency and the number of deposition cycles(X) was altered for the purpose of optimization. For the cell with novel TiO2NCs/TiO2NRs/PbS(X)/CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode, the highest efficiency was about 5.5% and achieved for X = 2. This power conversion efficiency (PCE) was enhanced about 28% compared to that of the PbS free photoelectrode. The other improved TiO2 NCs/TiO2HSs/PbS(X)/ CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode was also utilized with a light scattering HSs film. The maximum efficiency was achieved about 6.5% for the extra PbS(2) sensitizing layer. This PCE was increased about 20% compared to the PbS free photoelectrode and 51% compared to that of the QDSC with the PbS free, NRs included photoanode. The highest efficiency was attributed to the co-sensitization and optimized PbS sensitizing layer together with the effective light scattering and utilization of double passivating layers.
|