A dye/polymer based solid state thin film photoelectrochemical cell used for light detection

In the present investigation solid state polymer photoelectrochemical (PEC) cells have been fabricated for light detection using thin film of blends of optically active Safranine-T dye dispersed in polyvinyl alcohol (PVA) used as an inert polymer matrix and polyethylene oxide (PEO) complexed with ammonium perchlorate (NH4ClO4) ion salt as a solid electrolyte with ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers. A thin film (∼200 nm) of this blend is sandwiched between two transparent indium tin oxide (ITO) coated glass plates which act as the two contact electrodes. Upon application of an external bias voltage on the device the photo response is observed while illuminating the device from a tungsten lamp. The measured photosensitivity is about 0.20 μA mW−1 cm2 at a bias voltage of 3.5 V and at an incident intensity of about 40 mW cm−2. It is observed that the sensitivity depends on the bias voltage and the nature of this dependence is studied. From the observation on the growth and the decay of the photocurrent at different bias voltages the photosensitivity versus the bias voltage is evaluated. The characteristic feature that emerges from the present study is that the device can be used as a large area photodetector with a somewhat slower speed of response.