A BHJ-thin-film/liquid-electrolyte based electrochemical-sensor for visible light-detection

Abstract

The current study presents a new type of inexpensive and very sensitive bulk heterojunction (BHJ) organic photo-sensor (OPS) configuration that incorporates a layer of liquid electrolyte into the conventional BHJ photodiode arrangement. Initially, a P3HT:PCBM blend based photo-anode was deposited onto ITO substrates using spin coating. Then the semiconductor coated photo-anode was attached to a Pt/ITO counter electrode. A 40m gap between photo-anode and counter electrode was filled with a liquid (iodine based) HI-30 electrolyte. Various electrical parameters including ideality factor, series and shunt resistance were extracted from the current-voltage characteristics under dark and light conditions. The value of mobility measured under dark conditions was found to be 25.58 ? 10-6 m2 V-1 s-1. In addition, the samples were found to have a series and shunt resistance of 133.33 and 74.70k, respectively. Under illumination, the fabricated photodiodes exhibited a linear current-irradiance relationship, with a rapid response time, when exposed to transient light, thus making the newly proposed hybrid BHJ photo-diode configuration a potential alternative to the conventional photo-sensors.