Zhengrong Shi

The influence of metallic belt on aluminum back surface field of solar cells during the firing process

For normal solar cell production, the front surface is upturned and the Al rear surface directly contacts with the belt during the firing process. In this paper, the influence of metallic belt on the Al back surface field was investigated. With the development of light induced plating technology, it was possible that the rear surface was upturned so that the rear surface would not directly contact with the belt. For normal structured P-type cells, the rear surface upturned (RSU) method narrowed conversion efficiency distribution. With the efficiency growing, the advantages of RSU were seen more clearly. For Al rear emitter N-type solar cells, RSU was good for the quality of rear junction. The internal quantum efficiency at the long wavelength was improved a lot. The average efficiency increased by about 0.2%(abs). The best efficiency increased to 19.93%. Additionally, RSU also reduced the rear surface void ration in passivated emitter and rear contact (PERC) cells. The average efficiency of RSU PERC cells also increased by about 0.2%(abs). The best efficiency of PERC cells with RSU method was improved to 20.38%. The most important improvement came from the rear contact. In this paper, the environment tolerance of the cells was also studied. The thimbles of the belt destroyed the Al film and made the film loose. RSU method avoided direct contact of the Al film and the belt, and made the Al films compacter during the firing process. The performances of the cells in a hot and humid environment were improved. The aspects of rear surface almost did not change after water boiling. The efficiency degradation was lower than that of the normal firing mode. RSU method was good both for the cells efficiency and the stability improvement.

The investigation and optimization of LiF cathode buffer layer based on ZnPc/C 60 solar cells

Using electrode buffer layer is one of effective ways to enhance electric performances of organic solar cells. And LiF is the widest materials, which is used as a cathode buffer layer. In this paper, small molecule organic solar cells based on ZnPc and C60 are fabricated. And the LiF cathode buffer layer is studied. The mechanisms and functions of LiF layer are summarized and qualitatively explained. The thickness of LiF is also investigated. And it is found that its optimum thickness must be controlled at the interval from 1.0nm to 1.5nm.

Optimization of the structure of bilayer organic solar cells based on light intensity distribution and quantity of effective excitons

The light intensity distribution inside organic solar cells is described by optical propagation matrix and the quantity of effective excitons is defined in this paper. The quantity of effective excitons describes the total intensity near the donor/acceptor interface, which can contribute to the generation of holes and electrons. The optimum structure then can be obtained by maximizing this parameter. In this paper, CuPc/C60 structure is taken as an example. It is found the optimum structure is CuPc(15nm)/C60(40nm). The verification experiments are established and only 5nm error appears in the thickness of CuPc.