No 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 380 mV, short circuit current (J sc ) of 1.2 mA/cm 2 , and a photocurrent of 2.9 mA/cm 2 were observed for the solar cell annealed at 300°C for 1 min. 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 509 mV and J sc of 4 mA/cm 2 with a high photocurrent of~12 mA/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.

No abstract

Copper-rich interfacial-layer (Cu-rich IL) is formed during sputter deposition of cupric oxide (CuO) layer on silicon (Si). It has significant impact on the performance of p-CuO/n-Si heterojunction solar cells. In this report, CuO films deposited on Si at different RF-power levels using single and two-step RF-sputtering techniques and p-CuO/n-Si heterojunction solar cells have been investigated. Systematic characterization using XPS, AFM, XRD, Raman, and HR-TEM reveal that two-step RF-sputtering technique offers better crystal quality CuO film with thinner Cu-rich IL layer. Photovoltaic (PV) properties with an open-circuit voltage (Voc) of 421 mV, short circuit current (Jsc) of 4.5 mA/cm2, and a photocurrent of 8.3 mA/cm2 have been achieved for the cells prepared using two-step sputtering method, which are significantly higher than that for the solar cells fabricated using a single-step sputtering. The PV properties were further improved by depositing CuO films at higher working pressure with nitrogen doping. The efficiency of the best device achieved is approximately 1.21%, which is the highest value reported for p-CuO/n-Si heterojunction based solar cells.

No abstract