Solar cell emitting electrode corroding method

[0020] Example 1

[0021] Equipped with additive-free hydrofluoric acid and nitric acid etching solution, in which HF: HNO 3 : H 2 O (volume ratio of saturated solution) = 1:3:20; then configure the hydrofluoric acid and nitric acid etching solution with additives, in which HF:HNO 3 : H 2 O (volume ratio of saturated solution) = 1:3:20, the addition amount of sodium nitrite is 0.2mol/L, the addition amount of sodium sulfate is 0.1mol/L, the two mixed solutions are fully stirred and the temperature is stable At 20±2℃.

[0022] Take two single crystal silicon wafers with a size of 125×125mm. After cleaning, texturing, and diffusion, the square resistance is 30 ohms/square. One is etched in a mixed solution of hydrofluoric acid and nitric acid without additives for 120 seconds. After being etched in a mixed solution of hydrofluoric acid and nitric acid with additives for 120 seconds, the two silicon wafers were cleaned with a dilute alkali solution. After testing, the square resistance of the silicon wafers after etching in the etching solution without additives was 30-60 ohms. / Square, and the silicon chip resistance after etching in the additive-added etching solution is between 50 and 55. The prepared two batteries have high open circuit voltage after etching in the additive-added etching solution. 13mV, short-circuit current density increased by 1mA/cm 2 , The conversion efficiency is increased by 0.32% (absolute value).

[0023] Example 2

[0024] Equipped with additive-free hydrofluoric acid and nitric acid etching solution, in which HF: HNO 3 : H 2 O (volume ratio of saturated solution) = 1:3:20; then configure the hydrofluoric acid and nitric acid etching solution with additives, in which HF:HNO 3 :H2O (saturated solution volume ratio) = 1:3:20, the addition amount of sodium nitrite is 0.2mol/L, the addition amount of sodium sulfate is 0.1mol/L, the two mixed solutions are fully stirred and the temperature is stable At 20±2℃.

[0025] Take two single-crystal silicon wafers with a size of 125×125mm. After cleaning and texturing, the square resistance after diffusion is 30 ohms/square. Both wafers are screen-printed with an etching mask on the emitter and dried. One piece was etched in the mixed solution of hydrofluoric acid and nitric acid without additives for 150 seconds, and the other piece was etched in the mixed solution of hydrofluoric acid and nitric acid with additives for 150 seconds. The two silicon wafers were cleaned with a dilute alkaline solution and the etching mask was removed. Prepared into a selective emitter structure. After testing, the sheet resistance of the silicon wafer after etching in the etching solution without additives is between 40 and 80 ohms/square, while the sheet resistance of the silicon wafer after etching in the etching solution with sodium nitrite is 85 to 91 Between the two prepared selective emitter batteries, the open circuit voltage of the battery after corrosion in the additive-added corrosion solution is 22mV higher, and the short-circuit current density is increased by 2mA/cm 2 , The conversion efficiency is increased by 0.47% (absolute value).