The study of the photo-response characteristics of organic photosensors integrated with pentacene based thin film transistors

We have investigated the photo-response characteristics of organic photosensors (OPS) integrated with pentacene based thin film transistors (TFTs). The fabricated device configuration is PEN/ITO/PEDOT:PSS/(poly(3-hexylethiophene)/phenyl-C61-butryic acid methyl ester) (P3HT/PCBM)/Al and PDMS/Au/(poly-4-vinyphenol) (PVP)/pentacene/Au. In order to study the effect of the applied voltage to the pentacene-TFT on the OPS, each device is connected in series. The response current is tuned dependant on the gate-source voltage and the anode-source voltage. The change of the photo induced ON current in the integrated device is measured under light illuminations ranging from 50 mW/cm2 to 500 mW/cm2; the corresponding photo-response (ΔI/I0) of the devices varied from 0.16 to 1.9. We found that the photo-response characteristic is high at the low anode-source voltage and high gate-source voltage.