Blocking layer modeling for temperature analysis of electron transfer rate in quantum dot sensitized solar cells

Abstract

In this article, we simulate thermal effects on the electron transfer rate from three quantum dots CdSe, CdS and CdTe to three metal oxides TiO₂, SnO₂ and ZnO₂ in the presence of four blocking layers ZnS, ZnO, TiO₂ and Al₂O₃, in a porous quantum dot sensitized solar cell (QDSSC) structure, using Marcus theory. We considered blocking layer as being on quantum dots and metal oxide, and we approximated quantum dots-blocking layer in the form of a sphere with new epsilon and radius. We import blocking layer effect in the Coulomb energies, which leads to the correct conduction band edges of the quantum dots and free energy of system and finally the Marcus equation. We obtained the results for the temperature range 400-250 ° K which show that, increasing temperature for different combinations and blocking layers can give decreasing, increasing or decreasing-increasing trends. For ZnO-CdTe combination, blocking layers ZnO, ZnS, TiO₂, Al₂O₃ respectively, and for the other combinations, ZnO, TiO₂, Al₂O₃, ZnS respectively, have owned the highest rate. For verifying the simulation method, one of the experimental works performed by other researchers in the field of blocking layer was regenerated, that was in good agreement with our method with 3 percent error.

The results obtained in this study can be better interpreted for empirical observations and also in the design and selection of MO-QD appropriate combinations in the presence of blocking layer in QDSSCs by considering the applied thermal effects.

Keywords: electron transfer rate; temperature; quantum dot; metal oxide