Light Trapping and Down-Shifting Effect of Periodically Nanopatterned Si-Quantum-Dot-Based Structures for Enhanced Photovoltaic Properties

Authors

  • Jun Xu,

    Corresponding author
    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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  • Shenghua Sun,

    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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  • Yunqing Cao,

    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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  • Peng Lu,

    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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  • Wei Li,

    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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  • Kunji Chen

    1. National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Key Laboratory of Advanced Photonic and Electronic Materials of Jiangsu Province, Nanjing University, Nanjing, P. R. China
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Abstract

Periodically nanopatterned Si structures have been prepared by using a nanosphere lithography technique. The formed nanopatterned structures exhibit good anti-reflection and enhanced optical absorption characteristics. The mean surface reflectance weighted by AM1.5 solar spectrum (300–1200 nm) is as low as 5%. By depositing Si quantum dot/SiO2 multilayers (MLs) on the nanopatterned Si substrate, the optical absorption is higher than 90%, which is significantly improved compared with the same multilayers deposited on flat Si substrate. Furthermore, the prototype n-Si/Si quantum dot/SiO2 MLs/p-Si heterojunction solar cells has been fabricated, and it is found that the external quantum efficiency is obviously enhanced for nanopatterned cell in a wide spectral range compared with the flat cell. The corresponding short-circuit current density is increased from 25.5 mA cm2 for flat cell to 29.0 mA cm2 for nano-patterned one. The improvement of cell performance can be attributed both to the reduced light loss and the down-shifting effect of Si quantum dots/SiO2 MLs by forming periodically nanopatterned structures.

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