Benefits of photonic management strategy for highly efficient bifacial solar cells

Bifacial solar cells have received great attention due to their higher power generation capacity compared to monofacial solar cells. However, insufficient infrared absorption becomes an obstacle to enhance the performance of bifacial solar cells. In this work, the distributed Bragg reflector (DBR), which is one of the most promising photonic management strategies, is innovatively applied to the backside of bifacial solar cells to improve the light absorption for long wavelengths (950-1100 nm). Through the application of MgF2/TiO2 DBR at the rear side of bifacial solar cells, infrared absorption is enhanced for solar cells with different backside pyramid angles and wafer thickness. Experimental results suggest 20 degrees is the most effective backside pyramid angle for the enhancement of infrared absorption. With this DBR reflector, the infrared energy loss is also sharply reduced for thinner wafers. The improvement of the short-circuit current for two typical bifacial solar cells (the passivated emitter and rear cell and the heterojunction with intrinsic thin-layer solar cell) further verify the absorption enhancement through the management of this backside photonic crystal. Our work demonstrates that the DBR technology is a promising candidate for more efficient bifacial solar cells.