Fabrication Of Transition Metal Oxides/silicon Heterojunctions For High-performance Photovoltaic Conversion Applications

Transition metal oxides have been widely used in optoelectronic devices due to their unique carrier selection.The transition metal oxides/silicon heterojunction holds great promise for photodetectors and solar cells owing to its excellent photoelectric properties.In this paper,molybdenum oxide/silicon heterojunction and cuprous oxide/silicon heterojunction photovoltaic devices were systematically studied.The following conclusions are drawn:1.A novel photodetector based MoO_3-x/NPPAs silicon heterojunction with ultra-fast response（870 ns）,high detectiviety of 1.27×10¹³ jones and wide-bandwidth of 50 kHz operation at 0 V bias are fabricated by simple thermal evaporation.Furthermore,the temperature-dependence of photoresponse was systematically investigated to probe the carrier transportation within the heterojunction.A model is proposed in which carrier diffusion dominates the photoresponse performance.Finally,the temperature-resistant NPPA based heterojunction photodetector is successfully integrated into a visible light communication system and its application as an optical signal receiver for transmitting texts with 50 kbps is demonstrated.2.The CuI/Si and Cu₂O/Si heterojunction were fabricated by solution method and in situ reaction method respectively.The study of photo-detection performance shows that the Cu₂O/Si heterojunction’is over than CuI/Si heterojunction’.Furthermore,the energy band analysis by UPS explains the difference between these two devices performance.Finally,the performance of Cu₂O/Si heterojunction have been improved by optimum of precursor solution concentration.A high responsivity of 417 mA W^-1 at a wavelength of 920 nm and efficiency of over 3%are achieved in optimum device.3.Based the above work 2,we systematically carried out the optimization of Cu₂O/Si heterojunction solar cells.The high efficiency of 9.54%is achieved by a series of optimization means including improved the quality of Cu₂O film,add TCO to improve FF,surface passivation by HNO₃ to improve V_oc,improved back contact to enhance efficiency,and AR coating to improve J_sc.