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Open Access Nano Express

Performance-improved thin-film a-Si:H/μc-Si:H tandem solar cells by two-dimensionally nanopatterning photoactive layer

Cheng Zhang, Xiaofeng Li*, Aixue Shang, Yaohui Zhan, Zhenhai Yang and Shaolong Wu

Author Affiliations

Institute of Modern Optical Technologies & Collaborative Innovation Center of Suzhou Nano Science and Technology, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China

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Nanoscale Research Letters 2014, 9:73  doi:10.1186/1556-276X-9-73

Published: 12 February 2014

Abstract

Tandem solar cells consisting of amorphous and microcrystalline silicon junctions with the top junction nanopatterned as a two-dimensional photonic crystal are studied. Broadband light trapping, detailed electron/hole transport, and photocurrent matching modulation are considered. It is found that the absorptances of both junctions can be significantly increased by properly engineering the duty cycles and pitches of the photonic crystal; however, the photocurrent enhancement is always unevenly distributed in the junctions, leading to a relatively high photocurrent mismatch. Further considering an optimized intermediate layer and device resistances, the optimally matched photocurrent approximately 12.74 mA/cm2 is achieved with a light-conversion efficiency predicted to be 12.67%, exhibiting an enhancement of over 27.72% compared to conventional planar configuration.

Keywords:
Tandem solar cells; Photonic crystal; Photocurrent matching