Preparation And Photoelectronic Properties Of N-type Cuprous Oxide

With increasing of the non-renewable resources exhaustion, such as oil, natural gas, it is very urgent for human to seek a renewable energy source. However, the efficiency of solar energy utilization is still at a low level up to now, and there is always a need of further research to realize the comprehensive applications. Moreover the Cuprous oxide (Cu2O) which composed of two very abundant and non-toxic elements is a naturally p-type semiconductor with an band gap of 1.95 eV at room temperature. The theoretical efficiency of Cu2O solar cells is about 20%. So Cu2O has always been considered a material suitable for the realization of low cost solar cells. Due to the high surface resistivity and the difficulties in doping of Cu2O, so far the conversion efficiency of solar cell based on Cu2O is generally low.The key problem to improve the photoelectrical efficiency is how to prepare Cu2O with low resistivity. Doping, as a common practice to control the conduction type and resistivity of a semiconductor, has been applied to research preparation of Cu2O for photovoltaic materials. In order to reduce the resistivity of Cu2O, we use the KCl as the precursor of Cl to prepare the Cl-doped Cu2O by electrodeposition in acid electrolyte. The influence of chlorine doping on grain size, crystallite shape and orientation was examined. The band gap is estimated by the optical absorption spectrum. And the surface photovoltage spectra is used to investigate the transfer behavior of photogenerated charges in Cu2O. Our results show that the samples are all n-type conductivity and the Cl doped Cu2O has a more stable conductivity type and superior photoelectrochemical properties.A SILAR method has been used to fabricate the PbS/Cu2O composite structure. PbS is p-type semiconductor with a narrow band gap and a wide spectral absorption range. The unique multi-exciton generation (MEG) effect and quantum size effect of PbS have a large utilization of sunlight.The absorption of optical is widened to near infrared region and the the photo-current has greatly improved after the modification of PbS. The top photoelectric conversion efficiency is only 0.67%, which due to the interface state between the mismatched band gap of PbS and Cu2O.