A high-efficiency selective emitter solar cell laser doping method

Abstract

The invention provides an efficient selective emitter solar battery laser doping method. The method comprises the following steps: (1) cleaning and texturing a crystal silicon wafer, and performing primary impurity diffusion on the silicon wafer by adopting a thermal diffusion process to form a pre-coated layer on the surface of the crystal silicon wafer; (2) conveying the crystal silicon wafer to the lower side of a mask plate till the geometric center of the crystal silicon wafer is overlapped with the geometric center of the mask plate, the light leaking gap of the mask plate is overlapped with a fine grid of a battery piece on the crystal silicon wafer, and the mask plate clings close to the crystal silicon wafer; (3) performing laser scanning doping by using strip-shaped uniform laser beams. Compared with the prior art, the efficient selective emitter solar battery laser doping method has the advantages that the laser energy can be utilized more fully, the blue light response reduction can be avoided, the PN-junction local breakdown can be avoided, the uniformity of the doping depth is increased while the laser doping efficiency is increased, and non-uniform battery deformation caused by local doping is reduced.

Description

technical field [0001] The invention relates to laser doping selective emitter technology, in particular to a high-efficiency selective emitter solar cell laser doping method. Background technique [0002] Selective emitter technology is an important means for manufacturers of crystalline silicon solar cells to improve cell efficiency and reduce cost per watt. Due to the characteristics of low cost, low investment and compatibility with traditional solar cell production lines, the laser doping process has attracted much attention. The direct laser doping method has a simple and controllable process, can achieve regional heavy doping, has a high activation rate, and has a very obvious effect on improving the photoelectric conversion efficiency. However, due to the large radius of the laser beam waist spot, the uneven distribution of beam energy density, high energy density in the center and low energy density in the periphery, the direct laser doping method has certain disad...

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Problems solved by technology

However, due to the large radius of the laser beam waist spot, the uneven distribution of beam energy density, high energy density in the center and small energy density in the periphery, the direct laser doping method has certain disadvantages.

For example, the surface distribution of the heavily doped region is wider, which reduces the absorption of short-wavelength photons in the emitter region, that is, reduces the blue light response of the battery; the doping depth of the central region is large, which easily leads to local conduction between the N+ region and the P+ region of the battery. That is, it causes partial breakdown of the PN terminal, which leads to battery failure.

In addition, the traditional laser doping process uses a Gaussian beam to scan the front electrode area one by one, which takes 2-3 seconds for each cell, and the efficiency is low

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