Development of high efficiency large area silicon thin film modules using VHF-PECVD

• Published in: Solar energy 2004-01, Vol.77 (6), p.951-960
• Main Authors: Takatsuka, Hiromu, Noda, Matsuhei, Yonekura, Yoshimichi, Takeuchi, Yoshiaki, Yamauchi, Yasuhiro
• Format: Article
• Language: English
• Subjects: Amorphous silicon; High deposition rate; Large area deposition; Microcrystalline silicon; PECVD; Photovoltaic cells; Silicon wafers; Solar cell; Solar energy; Tandem cell; Thin films; VHF
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2004.06.007

This paper reviews recent work on the development of thin film silicon solar modules and cost-effective production technology. Noting the potential of VHF-PECVD for high rate and high quality deposition, we initiated development of a-Si solar modules. In the first stage, we succeeded in up-scaling a-Si high quality uniform deposition at a high rate of over 1.0 nm/s to a substrate area of 1.1 × 1.4 m 2 to achieve high productivity. Next, the large area a-Si solar modules with stable aperture efficiency of 8% were developed, and the commercial production of a-Si solar modules commenced in October 2002. In the second stage, aiming at stable efficiency of 12%, which could make the PV power generating cost below residential electricity prices in combination with cost-effective production technology, we have been developing a-Si/μc-Si tandem solar modules. Recently, tandem modules of 40 × 50 cm 2 in size with a μc-Si i-layer prepared at a deposition rate of 2.1 nm/s yielded initial conversion efficiencies of 11.1%. As for small sized μc-Si single cells, technologies with a high deposition rate of 2.5 nm/s and efficiency of 8.8% have already been developed. In addition, by improving the up-scaling and light-trapping techniques, we will achieve our current goal of 12% stable efficiency for a-Si/μc-Si tandem modules at a deposition rate of over 2.0 nm/s, leading to cost-effective mass production.