ABSTRACT
As-deposited CuInSe2 thin films by electrodeposition method are usually accompanied with amorphous structure which is regarded detrimental for solar cell conversion efficiency. In this work, we proposed an annealing method under high pressure for improving the conversion efficiency of electrodeposited CuInSe2 thin film solar cells, and the microstructure of high-pressure annealed CuInSe2 films were also investigated. The annealing pressure was set from 100 kPa to 250 kPa, and the annealed CuInSe2 thin films were then fabricated into solar cell using standard process. Field-emission scanning electron microscopy (FESEM) images show that CuInSe2 films with higher annealing pressure demonstrate denser and smoother surface morphology. Results from X-ray diffraction (XRD) and Raman spectra indicate that annealing under high pressure enhanced the (1 1 2) preferential orientation of CuInSe2 films and also eliminated binary CuSe phases. Finally, through annealing CuInSe2 absorber layer under 200 kPa, the fill factor of the CuInSe2 solar cell was found to be improved from 28.4% to 55% and the efficiency from 2.77% to 6.91%.
ABSTRACT
Photo-assisted one-step electrodeposition has been applied to help in forming smooth and dense CuInSe2 films. The difference in surface morphology and crystalline quality between CuInSe2 films with various photo-assistance has been investigated. In the photo-assisted electrodeposition process, the many kinds of lamps providing maximum light intensity at about 380 to 620 nm were used as light source to be irradiated onto the surface of Mo-coated soda-lime glass substrates. The results suggested effects of photo-assistance including activating surface diffusion and growing high-crystalline quality films with reduced defects during electrodeposition.
