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Published online: 15 July 2009 | doi:10.1038/nchina.2009.145

Photovoltaics: The sky is the limit

Felix Cheung

Introduction

© (2009) AIP

A photovoltaic (PV) device capable of converting sunlight into electricity with high efficiency could help solve the global energy crisis. Last year, Changxin Chen, Yafei Zhang and co-workers at Shanghai Jiaotong University¹ demonstrated a PV device with a high power conversion efficiency of up to 12.6%. Now, the researchers² claim their device can exceed 40% efficiency.

The PV device features an array of carbon nanotubes welded between palladium and aluminium electrodes atop a semiconductor wafer (see image). Photons from sunlight generate electron–hole pairs in the wafer, converting the solar energy into electrical energy. The nanotubes facilitate the separation of these electron–hole pairs, which assists light absorption and excitation in the wafer.

The researchers used a 'Green's function' approach to obtain the current–voltage characteristics of the device system, which allowed them to simulate the PV effect and conversion efficiency for single wavelengths of light. They found that the gate voltage and gate oxide thickness have a strong influence on device performance, but more importantly, that the maximum conversion efficiency suggested by their calculations is 47.88%. Based on this finding, the researchers anticipate their device to have great potential in the PV field.

The authors of this work are from:
National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiaotong University, Shanghai, China.

References

1. Chen, C., Lu, Y., Kong, E. S., Zhang, Y. & Lee, S. T. Nanowelded carbon-nanotube-based solar microcells. Small 4, 1313–1318 (2008).
    | Article | PubMed | ChemPort |
2. Chen, C., Zhang, W., Kong, E. S. W. & Zhang, Y. Carbon nanotube photovoltaic device with asymmetrical contacts. Appl. Phys. Lett. doi:10.1063/1.3136905 (2009). | Article |