Efficiency enhancement and chrono-photoelectron generation in dye-sensitized solar cells based on spin-coated TiO 2 nanoparticle multilayer photoanodes and a ternary iodide gel polymer electrolyte

The effect of the thickness of a multilayer TiO 2 photoanode on the performance of a dye-sensitized solar cell (DSC) made with a polyethylene oxide-based gel polymer electrolyte containing ternary iodides and performance enhancer 4-tert-butylpyridine is studied. Multilayer photoanodes consisting of up to seven layers of TiO 2 nano-particles (13 nm and 21 nm) are prepared by spin coating of successive layers. XRD results confirm the predominant presence of the anatase phase of TiO 2 in the multilayer structure after sintering. The SEM images reveal the formation of a single TiO 2 film upon sintering due to merging of individually deposited layers. The photocurrent density ( J SC ) and the efficiency increase with the number of TiO 2 layers exhibiting the maximum efficiency and J SC of 5.5% and 12.5 mA cm −2 , respectively, for the 5-layered electrode of total thickness 4.0 µm with a 9.66 × 10 –8 mol cm −2 surface dye concentration. The present study introduces a method of determining the rate of effective photoelectron generation and the average time gap between two successive photon absorptions where the respective results are 1.34 molecule −1 s −1 and 0.74 s for the most efficient cell studied in this work.