Preparation And Photo-electric Properties Of Cu（In,Ga）Se₂and CuInSe₂/CdS Films

Along with social progress, economic development, energy demand higher and higher,while the depletion of non-renewable energy and the environment caused by pollution anddestruction has became one of the main problems of the21st century. The use of solar cellsdirectly convert solar energy into electrical energy is to solve the problems of energydepletion and the earth and environmental pollution is one of the best, one of the most directand most effective way. Various types of solar cells from Cu (In_1-xGa_x)Se₂（CIGS） as absorblayer of solar cells to become a research hotspot in the field of photovoltaic. CIGS is aI-III-VI family compound semiconductor materials, has a crystal structure of chalcopyrite. Itsband gap can be adjusted within the1.04-1.67range, with a direct band gap, and visible lightabsorption coefficient of up to105cm-1order of magnitude. CIGS thin film solar cell withhigh conversion efficiency, stable performance, low cost and so on become the mostpromising third-generation solar cell to achieve commercial production of solar cells. The keyis how low-cost preparation of large area, high-quality solar cells, the key part of the CIGSabsorber layer can achieve the commercial production of CIGS solar cells. CIGS thin filmprepared by electrodeposition method can achieve the preparation of large area, low prices,preparation of high efficiency, good stability of the preparation system, which has beenextensively studied, with a wide range of application development prospects. Our team hasprepared CIGS thin films by one step electrodeposition using a constant voltage, and thedeposition conditions and preparation of CIGS thin film optical and electrical properties wereanalyzed.In this paper, we make copper chloride, indium trichloride, gallium trichloride, seleniousacid as electrolyte, amino acid and potassium hydrogen phthalate as a buffer aqueous solution, CIGS thin films were deposited on the FTO glass substrate by one step electrochemicalmethod in a constant potential.The CIGS films were selenide annealed to improve thecrystallinity of the film and optimize the stoichiometry. By X-ray diffraction （XRD）, scanningelectron microscope （SEM）, energy dispersive spectroscopy （EDS）, and surface photovoltagespectrometer to sudy the characterization of the samples. From adjustting the pH value byadding the buffer amino acid and potassium hydrogen phthalate, we can avoid the generationof hydrogen in the deposition process. We conduct research and analysis prepared by one stepelectrodeposition of CIGS conditions and influencing factors.When the pH is2.0of theelectrolyte, annealing temperature is500°C, the crystallization effect and photoelectricproperties is best ideal.Finally, we deposit CdS thin films on the CIS thin-film by chemical bath deposition（CBD）, then remove the CdS thin films by hydrochloric acid. We use surface photovoltagespectroscopy （SPS） to study the CIS thin film surface photovoltage changes before and afterdepositing CdS thin films. The results showed that CdS thin films can enhance separationefficiency of the CIS thin films. We use the EDS to study the composition of CIS thin-filmbefore and after depositting CdS thin films. The results showed that we can find Cd elementin CIS thin film after remove the CdS, we think that this phenomenon is in the process ofdeposition of CdS, some Cd elements enter inside the CIS thin film by diffusion instead ofCu, to become CdCudonor, promote the CdS/CIS surface anti-type improve the CISsurface defects, to promote the photoinduced electron-hole pair separation, so that the opticaland electrical properties of CIS thin-film obtain enhancement.