Investigation of low-cost Cu2O-CuI based photovoltaic devices with near infrared response

Recently there has been a growing interest in thin films formed from low-cost, non-toxic semiconducting materials due to the promise shown for use in a wide variety of applications ranging from solar cells to environmental purification. In this study, we form n-type copper (I) oxide (n-Cu2O) thin films by boiling copper electrodes in copper (II) sulfate (CuSO4) solutions of varying molarity. Thin films of p-type copper (I) iodide (p-CuI) are then formed over the n-Cu2O films - thus completing p-n heterojunctions that are studied as photon-detecting devices with near infrared response. The devices have a final configuration of glass/FTO/Cu/n-Cu2O/p-CuI/graphite-FTO/glass. We characterize these devices via responsivity, capacitance-voltage (CV), and ultraviolet-visible-near infrared (UV-VIS-NIR) spectroscopy measurements. A peak photoresponsivity of 75mA/W at 575nm and 1mA/W at 943nm is observed at room temperature. The response data also indicates a variation in device response with film thickness -- we are making efforts to optimize these films to increase performance.