Abstract
Heterojunction solar cells of p-type cupric oxide (CuO) and n-type silicon (Si), p-CuO/n-Si, have been fabricated using conventional sputter and rapid thermal annealing techniques. Photovoltaic properties with an open-circuit voltage (V-oc) of 380mV, short circuit current (J(sc)) of 1.2mA/cm(2), and a photocurrent of 2.9mA/cm(2) were observed for the solar cell annealed at 300 degrees C for 1min. When the annealing duration was increased, the photocurrent increased, but the V-oc was found to reduce because of the degradation of interface quality. An improvement in the V-oc resulting to a record value of 509mV and J(sc) of 4mA/cm(2) with a high photocurrent of similar to 12mA/cm(2) was achieved through interface engineering and controlling the phase transformation of CuO film. X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analysis have been used to investigate the interface properties and crystal quality of sputter-deposited CuO thin film. The improvement in V-oc is mainly due to the enhancement of crystal quality of CuO thin film and interface properties between p-CuO and n-Si substrate. The enhancement of photocurrent is found to be due to the reduction of carrier recombination rate as revealed by transient photovoltage spectroscopy analysis.