Electrochemical Synthesis and Photovoltaic Property of Cadmium Sulfide−Polybithiophene Interdigitated Nanohybrid Thin Films

Interdigitated hybrid films consisting of cadmium sulfide (CdS) nanorod arrays and interpenetrating polybithiophene have been synthesized by electrochemical depositions. The vertically aligned CdS nanorods were self-assembled on gold-coated glass substrates through a simple cathodic process of an electrolyte solution containing cadmium sulfate and potassium thiocyanate, without the use of any templates. The conjugated polymer polybithiophene was deposited into the nanorod arrays by in situ electrochemical polymerization. The resulting interdigitated nanohybrid films showed dense packing of the polymer in the nanorod arrays with a filling ratio estimated to be 76%. Raman spectroscopy and Fourier transform infrared revealed charge-transfer between the polymer and the CdS nanorods, consistent with the high filling ratio and improved polymer−CdS interface. Solar cells based on these hybrid films with vapor-deposited aluminum cathode exhibited a diode characteristic with a rectification ratio of 10 3 at ± 1 V. The measured open-circuit voltage was 0.84 V, and the short-circuit current was 0.52 mA/cm 2 . The overall power conversion efficiency was 0.38%.