Abstract
We have studied the optical and photoelectrical properties of liquid state photoelectrochemical cells (PECs) based on photoactive electrodes based on poly (phenyl azo methane thiophene) (PPAT) and a composite film of nano-crystalline titanium dioxide (nc-TiO 2) and PPAT. The device fabricated with nc-TiO 2/PPAT photoactive electrode shows better performance with an open circuit voltage ( V oc) 0.56 V, short circuit photocurrent ( J sc) = 0.87 mA/cm 2 and fill factor (FF) = 0.58 under illumination with white light intensity of 10 mW/cm 2. We have analyzed the experimental results by comparing the IPCE spectra of both devices. It is observed that the device with nc-TiO 2/PPAT photoactive electrode shows better photovoltaic response as compared to the device based on PPAT photoactive electrode. This indicates that PPAT shows its p-type semiconducting behavior in the device based on PPAT, while in the device based on nc-TiO 2/PPAT photoactive electrode, the PPAT acts as a sensitizer to nano-crystalline TiO 2. The PEC based on TiO 2/PPAT photoelectrode exhibit an exponential increase of low frequency device capacitance due to the diffusion of electrons along TiO 2 network. Effect of iodine doping in PPAT on the photovoltaic performance of PEC have been also studied.
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