Recognition of light sensing p-n junction for hetero-structure CuInSe2/TiO2 and CuInSe2/HF-TiO2: Study of carrier transport mechanism

Searching of electronic system with functionality is the epitome of the material research and in this context; nanomaterials CuInSe2 and TiO2 are the promising stars whose possible applications in electronic devices are just endless. However, the fabrication of junction based device using these two materials is most tantalizing prospect in material science is still at its rudimentary stage. In this letter, we report our recognition of current rectification behavior of CuInSe2/TiO2 heterojunction, identical to the I-V characteristics of p-n junction diode and the impact of white light on it. The HOMO-LUMO band positions of hydrothermally derived CuInSe2 and TiO2 nanomaterials indicate that in thermal equilibrium a built-in-potential must arise across the junction. The current-rectification ratio of the configuration Al/CuInSe2/TiO2/ITO is improved from 560 to 627 at voltage +/- 2 V on white light illumination and this kind of behavior is certainly offering us an unprecedented way to realize the CuInSe2/TiO2 hetero-junction as photo-sensing p-n diode. The device performance is improved further by replacing TiO2 with HF treated TiO2.