A Study Of The Optimization Of Amorphous Thin Film And BSF In Silicon Heterojunction Solar Cells

Silicon heterojunction cells have attracted great interest in photovoltaic applications because of its high conversion efficiency and all process can be carried out at low temperature. So far, only the HIT heterojunction solar cells of Japan Panasonic has realized industrialization, whose related technology and process was, nevertheless, of high confidentiality. Other international research institutions and enterprises have conducted a great deal of research on silicon heterojunction solar cells. As the research on silicon heterojunction solar cells in China starts late, there is a large gap between china and other international research institutions and enterprises. In this paper, the author studied the optimization of amorphous thin film and BSF in silicon heterojunction solar cells.In this paper,the passivation effect of amorphous intrinsic silicon thin film on silicon was studied based on HWCVD, Comparative analysis two widely used minority carrier lifetime testing methods. Silicon heterojunction solar cells were manufactured based on HWCVD, Al-BSF sintering process was optimized, single layer emitter heterojunction cells and double layer emitter heterojunction cells wre manufactured; Cooperation with enterprise, using thin film solar cells production equipment try to manufacture heterojunction silicon solar cells. Main conclusions were as follows:The passivation effect of amorphous intrinsic silicon thin film on silicon wafer surface was researched based on HWCVD. As increasing the deposition pressure, amorphous silicon thin film microstructure parameter R * decreased, vacancy defects in thin film also gradually reduced. As increasing the current of the wire, thin film microstructure parameter R * firstly increased then decreased, vacancy defects in thin film gradually increased. μ-PCD and RF-PCD test results were differences related to minority carrier lifetime surface distribution, their test results were big difference when uneven surface distribution, their test results were near when uniform surface distribution.Crystalline silicon heterojunction solar cells were manufactured based on HWCVD. Firstly Al-BSF sintering process was optimized and double emitter structure was introduced in heterojunction silicon solar cells. The single layer emitter cells performance with double layer emitter cells performance were compared, It was found that double layer emitter cells open circuit voltage, fill factor and short circuit current has increased, eventually double layer emitter cells efficiency increased by 3.03% than the single layer emitter cells.Amorphous silicon thin film were deposited based on thin film silicon solar cells manufacture equipment PECVD, BZO was deposited by LPCVD technique to manufacture silicon heterojunction solar cell. The intrinsic passivation layer of deposition pressure and hydrogen dilution ratio were optimized, the cell performance of Al-BSF structure cell and amorphous silicon back field structure cell were compared. It was found that the cells open circuit voltage, short circuit current density and the fill factor of Al-BSF structure has increased a lot. Quantum efficiency in long wavelength improved significantly. The conversion efficiency increased 2.35%.The BZO microstructure topography on surface textured cells was measured by using scanning electron microscopy. It was found that BZO surface grain growth appears to pyramid microscopic structure, the microstructure of the BZO provided effective light trapping. BZO deposited on surface textured cells made low reflectivity to about 5%.