Effect of TiO 2 blocking layer synthesised by a sol–gel method in performances of fluorine‐doped tin oxide/TiO 2 /dyed‐TiO 2 /electrolyte/pt/fluorine‐doped tin oxide solar cells based on natural mallow dye

Abstract

Titanium dioxide (TiO2) thin film prepared by sol–gel technique and deposed by spin coating was used as the blocking layer between fluorine doped tin oxide and dyed TiO2 photoanode deposed by doctor blade in dye-sensitised solar cell (DSSC). The synthesised films show a polycrystalline structure at annealing temperature of 400°C with small amount of amorphous phase observed at 300°C. The values of the electrical conductivity varies from 0.11 to 1.17 Ω−1 cm−1 for one and two layers thin films, respectively, and the corresponding activation energies decreased as a function of the thickness, it passes from 109 meV for one layer to 55 meV for two layers. The photoanode of the DSSC was sensitised by the mallow diluted in ethanol having absorption spectra with two peaks, one around 480 nm (blue light) and the second at 665 nm (red light) attributable to the chlorophyll mixture. Improvement of the electrical performance is due to the increased electron lifetime and decreased of the recombination process showed by the open circuit voltage decay measurement. The lifetime values increase from 0.80 ms for the cell without blocking layer to 1.24 ms for the cell based on the blocking layer.