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International Journal of Photoenergy
Volume 2014, Article ID 307643, 4 pages
http://dx.doi.org/10.1155/2014/307643
Research Article

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

Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan

Received 20 July 2014; Accepted 27 August 2014; Published 7 September 2014

Academic Editor: Teen-Hang Meen

Copyright © 2014 Kuen-Hsien Wu and Chia-Chun Tang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.