Locally doped solar cell and preparation method thereof

Abstract

The invention discloses a preparation method of a locally doped solar cell. The preparation method comprises the steps of 1) prearranging and drying doping slurry: prearranging the doping slurry in aposition where a film is to be opened, contacting the doping slurry with a silicon base layer, and carrying out drying; 2) depositing a dielectric passivation film layer on the back surface of the silicon base layer; 3) carrying out laser ablation: carrying out ablation on the dielectric passivation film layer in a metallization region on the back surface of the silicon base layer by laser in a position as same as that of prearranging the doping slurry in the step 1); and 4) carrying out metallization: preparing a metal electrode through a metallization process. The invention provides the locally doped solar cell and the preparation method thereof. Before the dielectric passivation film layer is deposited on the back surface, the doping slurry is prearranged in the metallization region onthe back surface; and when the laser ablation is carried out on the dielectric passivation film layer, the prearranged doping slurry is pushed into the silicon base layer by utilizing energy of the laser, so that the heavy doping and depth of the metallization region are realized, and the composite current of the metallization region on the back surface of the silicon base layer is reduced; and the large-scale production is realized.

Description

technical field [0001] The invention relates to the technical field of crystalline silicon solar cells, in particular to a locally doped solar cell and a preparation method thereof. Background technique [0002] Conventional rear passivation solar cell (PassivateEmitterandRearcell, PERC) structure rear silicon oxide / aluminum oxide / silicon nitride stacked passivation dielectric layer, which has excellent passivation effect on the surface of the cell and can reduce the surface recombination current to 15fA / cm 2 Below, the conversion efficiency of the battery is greatly improved. However, the recombination current in the metallized area on the back is as high as 600-1000fA / cm 2 , is the performance short board of PERC battery and the bottleneck of PERC battery efficiency improvement. At present, when the mass production efficiency of 5BB-SE-PERC cells in the industry reaches 22.2-22.5%, the improvement of the efficiency of the back metallization area at this time is largely d...

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Problems solved by technology

[0004] If you want to reduce the recombination current in the metallization area on the back, you need to increase the doping concentration in the metallization area. In the existing solutions, it cannot be properly solved in mass production.

The University of New South Wales adopts the mask thermal diffusion method, and can only use silicon oxide as the back passivation film, but now the aluminum oxide dielectric passivation film is widely used in mass production, and this layer of film can only withstand the temperature of about 600 ° C. For Boron diffusion at 900°C will cause alumina to crystallize and lose its passivation effect; the industry proposes a plan similar to CN103996746A to print boron paste first to achieve doping in the laser ablation process, but the implementation is greatly limited due to the blocking effect of the dielectric passivation film layer Due to the doping effect, sufficient doping concentration and depth cannot be achieved, which is much higher than the 10Ω doped sheet resistance obtained by the University of New South Wales

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