Studies Of CdS Thin Film And CIS Coating Layer

It’s an urgent task to find cheap and clean renewable energy resource, for the shortage ofconventional energy and environmental pollution have become more serious during this21stcentury. Solar energy is a clean and cheap renewable energy resource, especially,CuInSe2(CIS) solar cell is semiconductor material with direct band gap, with a number ofadvantages, such as low manufacturing cost， high stability, and less sensitive to theinstallation angle of intelligence buildings, which make CIS thin film solar cells become a hottopic.In our work, the buffer layer CdS thin film is prepared with the method of chemical bathdeposition, while observing the surface morphology and cross section with Scanning ElectronMicroscope(SEM), analyzing the composition with Energy Dispersive Spectroscopy(EDS)，using the X-ray Diffraction(XRD) to analyze the microstructure; Spectrophotometer was alsoused to characterize the information of semiconductor band gap. Studies show that CdS thinfilm has the best surface quality and performance when the concentration of cadmium acetateis (0.004～0.006)mol/L、ammonia is (0.3～0.5) mol/L and Cd2+/S2-is1:5. The thickness ofCdS thin film deposited is40～190nm.The crystalline quality of the films can be improvedafter annealing, especially, when the annealing temperature is300℃, the uniform and denseCdS thin film can be prepared, and the particle size increase from69nm to123nm.The CI(A)S powder is also mixed with conductive ink according to a certain proportion,and then, coating the mixture onto the Mo and glass substrate with the method of screenprinting. The coatings thickness40～75nm was measured, what’s more, it becomes thicker asthe ratio of solute increasing. The phase analysis shows that the grain size increases from11.5nm to14nm after annealing, but it will cause the lack of In if the temperature was toohigh. In addition, the interlayer and surface resistance will also grow with the increase ofpowder.At last, the CdS thin film was deposited on the coatings, and detecting the photocurrent.It was found that weak photocurrent was produced with the xenon lamp irradiation, but thephotocurrent is almost zero when the coatings placed in sunlight.