Investigation of photocurrent efficiency of ZnO/CdTe based Inorganic thin film solar cell

ZnO/CdTe based inorganic thin film solar cell was successfully fabricated. The efficiency of ITO/ZnO/CdTe/MoO₃/Al inorganic solar cell has been investigated. Open circuit voltage, short circuit current, fill factor and power conversion efficiency were calculated using current density-voltage characteristics. The SEM and AFM image indicate the good crystallinity and less roughness of the thin films, overall the quality of thin films are good. The effect of ZnO thickness varying from 50 nm to 150 nm was investigated and maximum efficiency of about 8.39 % was observed for the 100 nm thickness of ZnO layer. Initially as we increase the thickness of ZnO layer i.e. thicker the active layer, the more the excitons induced by light absorption. This increases the efficiency of solar cell. The thickness of ZnO ranging from 75-100 nm also support for perfect antireflection coating which increases the absorption of light. However, more increment in the ZnO thickness causes the build-in electric field weaker and the pathway becomes longer for transporting the opposite charge carriers derived from exiciton separation to their corresponding electrodes at the same time, which makes the probability of charges collection by respective electrodes lower. (author)