A Novel Bifacial c-Si Cell Structure and Process for High Efficiency and Low Cost

A novel structure of Ag grid/SiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:H/TCO/Ag grid is designed in order to increase the efficiency of bifacial amorphous silicon/crystalline silicon based solar cells (HJT) and reduce the rear materials consumption and manufacture cost. The simulation result done by AFORS-HET shows that the new structure could get higher efficiency compared with the normal bifacial HIT cell for the increase of the short circuit current, while it could keep most advantages of the HJT, such as: high voltage, low temperature coefficient and good weak light performance. A real cell composed of the novel structure with a size of 75mm*75mm was tried out by a special processing recipe, in which most techniques and machines are normally used in c-Si solar cell manufacture. Without any parameters optimization, the efficiency with light injected from the SiNx and TCO side reached 19.4% and 18.1% (AM1.5G, 25°C), respectively. The performance and the quantum spectra of the cell are compared with a normal bifacial HIT cell, and the result is constant with the simulation analysis. It could be concluded that the design is a advantageous structure and the processing recipe is worked.