This invention discloses a glass
powder for the main grid paste of TOPCon
crystalline silicon solar cells and its preparation method. The glass
powder is obtained by mixing glass frits A and B obtained after cold rolling at a
mass ratio of 1.5 to 2:1, followed by secondary melting and cold rolling. Glass
frit A includes PbO, SiO2, B2O3, Li2O, Na2O, etc., and glass
frit B includes Bi2O3, SiO2, AgNO3, B2O3, Li2O, Na2O, etc.
Distilled water is added to glass
frit B during the batching process to fully combine AgNO3 with other oxides, and the mixture is dried to a viscous state before
sintering. During the
sintering process,
laser-enhanced contact optimization technology is used to reduce AgO in the glass to silver microcrystals, thereby improving the
electrical performance of the main grid lines. The printed solar cells exhibit reduced
damp heat decay, resulting in high module reliability and improved
photoelectric conversion efficiency while ensuring high
welding tensile strength. The resulting glass
powder does not excessively etch the
silicon nitride and aluminum
oxide passivation layers, and the prepared
slurry can be sintered at 650-800℃, which can meet the requirements of the front and back main grid electrodes of TOPCon batteries.