Studies On Chemical Bath Deposition And Optic/Electric Properties Of Thin Films Of CIS Solar Cell Functional Layers

CuInS2 is a solar cell materials with superior performance. It has the following advantages, such as: high light absorption rate, its band gap being close to the optimum band gap solar cells, direct band gap semiconductor, being doped to both p-type and n-type semiconductor membranes, the highest theoretical conversion efficiency, and low cost. So, it is known as the most promising material for photovoltaic devices. This article aims to synthesize copper sulfide and zinc oxide thin films with high crystallinity and to study their optical and electrical properties by using low energy, environmentally friendly chemical bath deposition method, designing the experimental program, and optimize the experimental parameters. The main contents of this paper can be divided into two parts:1. CuS thin film was successfully prepared using traditional and microwave assisted chemical bath deposition method by designing reaction route, and also thermodynamics and kinetics processes of thin films preparaed by these two methods are compared. The reaction parameters such as: reaction time, pH value, and additive are investigated carefully to see how these parameters influence on the whole preparation process. By adjusting the parameters of these reactions, the preparation processes are under controlled. Therefore, CuS thin films are synthesized with a good crystalline, strict stoichiometric ratio, and a special surface morphology. The correlative optical and electrical properties are tested. Especially, the transmittance and reflection of the thin films are measured and the corresponding band gaps are calculated. Meanwhile, the electric resistivity is measured. The field emission properties of the as-prepared thin films are evaluated through alterating the testing method. The factors affecting on the field emission properties such as reaction time and chelations/additives are researched. Then the dominant factors which affect the field emission properties are derived by calculating the work function, geometric enhancement factor and effective emission area of the thin films.2. ZnO 1D nanorod arrays are prepared by designing reaction route, using chemical bath deposition. The reaction parameters such as the parameters of RF-sputtering, the category of the chelation and the environment of the solution are investigated. By adjusting these parameters, the growth of the nanorods are under controlled. A ZnO nanorod arrays with good crystalline, wurtzite structure and high c-axis orientation are obtained. Then, we select a red laser with the wavelength of 630 nm as a light source to prove whether these kind of one-dimensional ZnO arrays have light trapping effect or not. As we all know, the pure ZnO has a low electric resistivity. So, the Al doped ZnO n-type semiconductor is prepared. The haze of ZnO:Al 1D nanorod arrays are investigated by using UV-Vis spectroscopy, and the change of haze with the variation of the reaction time and Al dopant composition are tested. A set of comparative experiments including electrical resistivity test and Hall effect test are carried on both doped ZnO and undoped ZnO. Finally, we study the change of mobility and carrier concentration with the increasement of Al doping on the films.