Study Of Nanoparticle-based Printing Technology For CIS/CIGS Thin Film Solar Cell Absorber Layer

CIS/CIGS thin film solar cell has attracted much attention in recent years because of its many advantages, including good photostability, good weak-light characteristics, strong ability to resist radiation and demonstrated high conversion efficiency. Meanwhile, it can be prepared on flexible substrates. Therefore, it is regarded as the most promising next-generation low-cost solar cells.CIS/CIGS absorber layer, in which solar energy can be converted into electricity, is the core of CIS/CIGS thin film solar cell. The preparation of CIS/CIGS absorber layer is the foundation for the preparation of solar cells because high efficiency and long life CIS/CIGS solar cell relies on qualified CIS/CIGS absorber layer. In order to obtain a high quality film, the CIS/CIGS absorber layer is usually prepared by vacuum technologies. However, vacuum technologies have several limitations, such as high investment in equipment, low thin film deposition rate and low utilization of expensive raw materials(about 50%), which increase the manufacturing costs of solar cell and limit the scaling up commercial production. In recent years, non-vacuum technologies have been developed and gradually attract lots of attention because of its many advantages, e.g., simple processing equipment, low-cost, high utilization efficiency of raw materials, continuous deposition for large area under relatively low temperature. In the non-vacuum technologies, printing technology is one of the most promising technologies to prepare low cost solar cells because of its important advantages, e.g., high utilization efficiency of raw materials, high production efficiency, simple processing procedure, low-temperature production environment and compatibility with roll-to-roll production process. For printing technology, synthesizing near stoichiometric and excellent performance nanoparticles by a simple and rapid method and designing a high-efficient annealing plan to obtain high-quality absorber layer are two great challenges.In this thesis, absorber layer materials of CIS/CIGS thin film solar cell were firstly studied. Chalcopyrite and near stoichiometric CIS/CIGS nanoparticles were successfully synthesized by a facile and rapid one-pot method. Under different reaction temperature and reaction time, CIS nanoparticles were synthesized, the effects of reaction temperature and reaction time on the crystal phase, morphology, elemental composition and absorption spectrum of the as-synthesized CIS nanoparticles were investigated by XRD, SEM, EDS, TEM, Raman spectroscopy and UV-vis-IR spectrophotometer, respectively. The formation mechanism of CIS nanoparticles synthesized by one-pot method was also studied in detail. Replacing a part or all of In with Ga in the chalcopyrite CIS nanoparticles enabled continuous tuning of the band gap from 1.0 to 1.7 e V. Under different reaction temperature and reaction time, CIGS nanoparticles were synthesized, the effects of reaction temperature and reaction time on the properties of the as-synthesized CIGS nanoparticles were investigated. Under the optimal synthesis condition, CIGS nanoparticles with different Ga contents were synthesized, and the effects of Ga content on the properties of the as-synthesized CIGS nanoparticles were investigated in detail. The formation mechanism of CIGS nanoparticles synthesized by one-pot method was also studied. The results indicated that the as-synthesized CIS/CIGS nanoparticles had a single phase chalcopyrite structure, the element composition was near stoichiometric, and the nanoparticles had a good dispersibility. Therefore, the CIS/CIGS nanoparticles synthesized by the facile and rapid one-pot method were suitable for light absorber layer material.The as-synthesized CIS/CIGS nanoparticles were prepared into paste with a proper viscosity by adding appropriate amount of ethanol, ethyl cellulose and a-terpineol. Then, the absorber layer of CIS/CIGS thin film solar cell was prepared by screen printing method. We modified a rapid thermal annealing furnace, in which the CIS/CIGS absorber layer was rapidly annealed under selenium atmosphere. The effects of annealing temperature and annealing time on the properties of absorber layer were investigated in detail. The results indicated that the optimal annealing conditions were(600 oC, 15 min) for CIS absorber layer and(600 oC, 20 min) for CIGS absorber layer.In order to evaluate the photovoltaic performance of the absorber layer, the CIS/CIGS thin film solar cell with Glass/Mo/CIS(CIGS)/Cd S/i-Zn O/AZO/Al structure was prepared, and its photovoltaic properties were tested and analyzed.