The Preparation And Performance Investigation Of Cu-Based Thin Film Solar Cells Absobed Layer

With the rapid development of science technology, the global energy crisis and the extrusive environmental pollution make the point of researching and developing novel environment-protecting energy materials. Solar energy, as a kind of cleaning and effective energy, with the features of common irradiation, environment-friendly, huge reserves and long-term use, make the best candidate for all the energies. CISSe and CZTSSe are the most promising materials due to its excellent performance in solar cells, such as direct and tunable energy band gap, extraordinarily high absorption coefficient, long-term stability, high conversion efficiency, fine anti-interference and good radiation resistance. The performances of the solar cells depend on the absorber layer, so it has a good significance to investigate CISSe and CZTSSe thin films.This thesis is divided into two parts, the main contents and results are described as follows:In chapter3, CISSe thin films have been prepared onto soda-lime-glass substrates by selenization and sulfurization of magnetron sputtered Cu-In precursors. The factors, reaction and annealing conditions, which influence the performance of CISSe thin film, are studied in details. The results indicate the properties of the CISSe films are strongly dependent on the post-annealing treatment. After annealing at400℃for20min, the CISSe films have formed tetragonal (chalcopyrite) crystal structure and the diffraction peaks of the films shift systematically to the left with the temperature varying from400℃to500℃. EDAX study reveals that the compositions of CISSe films are Cu0.83In1.17S1.67Se0.3, Cu0.86ln1.13S1.61Se0.4and Cu0.82In1.15S1.54Se0.49after annealing at400℃,450℃and500℃, respectively. The direct optical band gaps of the films slightly decrease from1.44ev to1.32ev with the increase of the temperature from400℃to500℃, and the optical absorption coefficient is over105cm-1.The films annealed at400℃-500℃are all found to be p-type and the resistivity is almost10-2-10-3Ω·cm. The carrier mobility of the film at500℃is almost as high as1.701cm2/V·S.In chapter4, CZTSSe thin films were successfully prepared by selenization and sulfurization of CZTS nanocrystals synthesized with a new oleamide-based solution via drop-coating process. The factors, such as pressure, power, annealing temperature, time and amounts of Se, which influence the structure, the morphology, the composition and optielectrical properties of the thin film, were studied in details. And the performance of CZTS nanocrystals synthesized with a new oleamide-based solution are also studied. The results indicated that the CZTSSe films had formed a single-phase structure at450℃, their compositions were Cu, Sn rich and Zn poor. The electrical properties study suggested that the films were p-type, and the film annealed at500℃owned better electrical properties. The UV-vis spectroscopy showed that the CZTSSe films had strong optical absorption in the visible light region, and the observed band gaps are1.36eV and1.32eV at450℃and500℃, respectively. All the results indicate that CZTSSe thin film, owning a good opti-electrical property, can be prepared by controlling the reaction conditions and optimizing the parameters in the experiment.