The invention discloses a method for preparing a double-sided PN junction
solar battery, which comprises the following steps of: preparing matte structures on the front side and the back side of a
crystal silicon substrate; placing the
crystal silicon substrate of which the front side and the back side are provided with the matte structures in a
diffusion furnace to perform
diffusion so as to form a double-sided PN junction structure; photoetching and corroding the back side of the
crystal silicon substrate to form a positive
electrode gate groove of the
solar battery; oxidizing the front side and the back side of the crystal silicon substrate to form SiO2 films, and depositing Si3N4 films;
coating a
photoresist on the front side and the back side of the crystal silicon substrate, and performing photoetching
exposure and development to form positive and negative patterns on the back side of the battery and negative
electrode patterns on the front side of the battery; evaporating
metal electrodes on the front side and the back side of the crystal silicon substrate, and performing a stripping process; and performing
alloy annealing to prepare the double-sided PN junction
solar battery. The method uses two PN junctions of a crystal silicon battery for work to finally fulfill the aim of efficient conversion, has fewer process steps, is simple, can be compatible with a process on a large-scale
production line, and can realize large-scale production easily.