Efficiency Enhancement of Nanoporous SiliconPolycrystalline-Silicon Solar Cells by Application of Trenched Electrodes

Abstract EN

Trenched electrodes were proposed to enhance the short-circuit current and conversion efficiency of polycrystalline-silicon (poly-Si) solar cells with nanoporous silicon (NPS) surface layers.

NPS films that served as textured surface layers were firstly prepared on heavily doped p+-type (100) poly-Si wafers by anodic etching process.

Interdigitated trenches were formed in the NPS layers by a reactive-ion-etch (RIE) process and Cr/Al double-layered metal was then deposited to fill the trenches and construct trenched-electrode-contacts (TEC’s).

Cells with TEC structures (called “TEC cells”) obtained 5.5 times higher short-circuit current than that of cells with planar electrode contacts (called “non-TEC cells”).

Most significantly, a TEC cell achieved 8 times higher conversion efficiency than that of a non-TEC cell.

The enhanced short-circuit current and conversion efficiency in TEC cells were ascribed to the reduced overall series resistance of devices.

In a TEC cell, trenched electrodes provided photocurrent flowing routes that directly access the poly-Si substrates without passing through the high resistive NPS layers.

Therefore, the application of NPS surface layers with trenched electrodes is a novel approach to development of highly efficient poly-Si solar cells.