Double dye cubic-sensitized solar cell based on Förster resonant energy transfer

Abstract

To extend the solar spectral response range of dye-sensitized nanocrystalline semiconductor thin film solar cells, eosin Y (EY) and Rhodamine B (RB) were chosen to cubic-sensitize nanocrystalline ZnO thin film. A hybrid layer containing EY and ZnO (EY/ZnO) was first electrodeposited on a nanocrystalline ZnO thin film (n-ZnO) to form a structure of n-ZnO/EY/ZnO, and then RB was sensitized to form a double dye cubic-sensitized nanocrystalline ZnO thin film with a structure of n-ZnO/EY/ZnO/RB. The absorption spectra of the two organic dyes are complementary and the emission spectrum of EY overlaps with the absorption spectrum of RB. A new dye-sensitized solar cell based on the n-ZnO/EY/ZnO/RB thin film was fabricated, in which EY as an energy-relay dye simultaneously transfers both electrons and holes to the sensitizing dye of RB by the Förster resonant energy transfer (FRET) process. Thus the spectral response range of the fabricated dye-sensitized solar cell was extended and the energy conversion efficiency was improved. The thickness of the EY/ZnO hybrid layer is the key factor in affecting the conversion efficiency of the new solar cells, and it was optimized by changing the deposition time of the hybrid layer.