Preparation And Characterization Of CIS Thin Films By The Selenization Of Electrodeposited Cu/In Mutilayers

With increasingly serious energy crisis and environmental pollution problems, itbecomes more and more significant and urgent to develop and utilize novel energypossessing facinating properties such as safety, enviromental friend and reproducibility.Since solar energy is widely available and inexhaustible, it has become the first choicebeing applied to its corresponding varieties of technologies, in which photovoltaic powergeneration is the most potential and fast development application. Copper indiumselenium （CIS） solar cell is expected as the most commercially promotional photovoltaicdevice, due to its high light absorption ratio, high conversion efficiency, stableperformance and long service life. The essential element of the CIS solar cells is the CISphoton absorption layer, which can be prepared through multiple methods. In this thesis,we applied electrodeposition to fabricate CIS thin films, in order to reduce the cost,improve the quality of thin films, and be beneficial for industrialization production. Here,the main contents of my work are focused on the preparation of Cu/In multilayers andselenization treatment on continuous solid-state source, which are summarized asfollows.Firstly, Cu/In multilayer thin films were prepared by electrodeposition. Following,the effects of current density and electrodeposition time on the quality of these thin films,and various difficulties we faced during the process are also discussed here. Moreover,the morphology and composition of the films have been characterized and measured viascanning electronic microscopy （SEM） and energy dispersive spectroscopy （EDS）. TheCu/In multilayer films of ideal stoichiometric ratio were derived through our calculationultimately.Secondly, the Cu/In multilayer films were heat-treated with different time, and theresults showed that the Cu/In multilayers require shorter heat treatment time. Cu/Inbilayer thin films were also fabricated in order to compare its microstructure with that ofthe Cu/In multilayer films, and the results confirmed that the alloying heat-treatment timeof the Cu/In multilayers is shorter which could result in reducing energy consumptionand loss of In during the heat treatment. Thus, the surface of the Cu-In alloy film becomesmoother, denser and more uniform, which is accord with the requirements of highquality Cu-In precusor.Thirdly, a device for creating continuous selenium vapor with high activity has beendesigned to achieve the continuous solid-state source of selenization treatment. By using this device, highly active selenium steam can be supplied, which can reduce powerconsumption, at the same time, high efficiency and high-quality selenium products canbe obtained. We choose the solid sulphur powder as the raw resource and introduce theimproved device to carry out sulfurization under the protection of highly inert gases, thenthe compact films were deposited with grain size being about2μm. These filmsdemonstrate preferred orientation along （112）, and the corresponding ideal stoichiometricproportion of Cu, In and S was1:1:2. Meanwhile, the related electrical measurementsindicated that the CuInS₂thin film is P-type semiconductor with surface resistanceranging from100to500.