Water-soluble poly(3,4-ethylenedioxythiophene)/nano-crystalline TiO2 heterojunction solar cells

Nanocrystalline titanium dioxide (TiO₂) thin films were prepared by the sol-gel method and were then used to fabricate an indium-tin oxide (ITO)/nano-crystalline TiO₂/poly(3,4-ethylenedioxythiophene) (PEDOT)/Au device. The junction thus obtained shows a rectifying behavior. Their current-voltage (I-V) characteristics in dark indicate that a heterojunction at the nano-crystalline TiO₂/PEDOT interface has been created. The measured open-circuit voltage (V_oc) and short-circuit current (I_sc) for the device under illumination with 50 mW/cm² light intensity under AM 1.5 conditions (device dimension was 1 cm²) are V_oc=0.39 V, I_sc=54.9 μA/cm², the filling factor (FF)=0.429 and the energy conversion efficiency (η)=0.03%.