Study On The Effect Of Oxygen And Carbon Content On The Solar Cell Conversion Efficiency

The wide use of solar cells will be a feasible way to solve the energy and environmental protection problems. The development of solar cells is showing a tendency to improve efficiency and reduce cost. Crystal silicon solar cells are considered the most promising cells in the future for their advantages, such as high efficiency, great stability, simple processing, and none-pollution.To achieve this aim, the effect of oxygen and carbon content on the solar cell conversion efficiency are studied in this thesis. Three parts are studied in our work, Firstly, the effect of annealing on the oxygen and carbon content and minor carrier lifetime of CZ-Si are studied , then put it into the process of solar cell and compare the capability of solar cell in two process. The proper temperature is felt about from the substrate of P(100) CZ-Si ,and it is found that the solar cell conversion efficiency has been improved from 8.85% to 11.45% for the annealing process. Suitable processing conditions for cells' fabrication, hydrogen passivation, SiNx anti-reflection coating deposited by plasma enhanced chemical deposition (PECVD) are also studied .Secondly, the character of carbon and the effect of carbon on the oxygen deposition in annealing are studied . The most aim is to found the rule of carbon effects oxygen deposition and the change of minor carrier lifetime in annealing .Finally, the effect of boron and interstitial oxygen on the light degradation are studied. In this part, the issues and mechanism of light degradation of B-doped p-type CZ-Si solar cells are introduced firstly, it was clarified that boron and interstitial oxygen are major components of defect center for light degradation of B-doped CZ-Si solar cells. Then in the experiment the B-doped CZ-Si is chosen as the substrates and annealled at different temperature. The change of interstitial oxygen content and the change of minor carrier lifetime are studied. In order to avoid light degradation, low interstitial oxygen content and low boron concentration B-doped p-type CZ-Si material should be used , for example, the resistivity can be from 5-10 Ω.cm, the efficiency has reached to 22.0%. The necessary is to make BSF for good back contact.