Effect of Photoanode Modification on Charge Transport,Recombination and Efficiency of Dye Sensitized SolarCells Using Synthetic Organic Dyes

The DSSCs (Dye-sensitized solar cells) with photoanode using different sizes of particulate TiO2 (18 nm, 30 nm and 200 nm) have been fabricated. The synthetic organic dyes (LEG4) was used as photosensitizer. The present work mainly investigates the influence of TiO2 photoanode modification on light absorption, charge transport and carrier recombination which are then correlated to the device efficiency measured under AM1.5 solar irradiance. The DSSCs with photoanode using larger 200-nm-TiO2 as light scatterer outperform other devices without larger TiO2. It is attributed to an increase in harvesting photons (by UV-vis spectroscopic measurement) via light scattering, smaller ideality factor (by dark current analysis), thus lower recombination possibility, lower charge transfer resistance and longer electron lifetime (by electrochemical impedance spectroscopy) which results in longer electron diffusion and higher charge collection efficiency. The photoanode modification in DSSCs has a strong impact on optical and charge transport properties, and eventually on the photovoltaic performance.