Electron beam induced current characterization of solid-state dye sensitized solar cell

Abstract

Electron beam induced current (EBIC) was applied in the study of dye sensitized solar cell (DSSC), which present properties such as electrical stability, the possibility to use curved geometries, and cost-effectiveness. In the studied cells, the liquid electrolyte was replaced by a solid-state hole transport material (HTM) based on spiro-OMeTAD solution. Since the irradiation of electrons in a solar cell produces electron-hole pairs in a similar way as the photon irradiation, the EBIC measurements allowed the evaluation of the conductivity between FTO and electrolyte containing TiO2, the current homogeneity in the active layer, the EBIC signal behavior as a function of cell thickness, and the differences observed in the collection of electron and holes in each contact, leading to the mapping of the charge carrier generation and collection efficiency in the cross section of the DSSC. The combination of EBIC, grazing incidence X-ray diffraction (GIXRD) and Energy dispersive spectrometry (EDS/SDD) were used to demonstrate the homogeneity of the generated electrical current, phase and composition distribution in the studied cells. The enhancement in the electrical conduction between the contact layer (FTO) and the photoanode after treatment with TiCl4 was demonstrated. Our work demonstrates that EBIC can be used as an important support quality control technique of solid-state dye sensitized solar cells, indicating the need of efficiency improvement in regions like the interface between FTO/TiO2 and depth distribution of HTM into the cell.