Progress in the development of high-conversion-efficiency a-Si/μc-Si tandem solar module using μc-Si thin film with high deposition rate on Gen. 5.5 large-area glass substrate
The technology to make high-quality, high-reliability solar modules with a high deposition rate for μc-Si thin-film is a problem for the industrialization of low-cost, high-conversion-efficiency a-Si/μc-Si tandem structure solar modules. Sanyo has solved this problem by developing an original CVD technique called Localized Plasma Confinement CVD and a new evaluation method for μc-Si thin film. A stabilized conversion efficiency of 10.0% was achieved for an a-Si/μc-Si tandem structure solar module, and a deposition rate of 2.4 nm/s for μc-Si thin-film was attained on a Gen. 5.5 full-size glass substrate. To obtain a higher conversion-efficiency a-Si/μc-Si tandem structure solar module, fundamental studies of μc-Si thin-film have been performed, and a stabilized conversion efficiency of 10.5% (Initial solar module conversion efficiency: 12.0%) has been achieved on a large-area glass substrate. Furthermore, in the study of this development, the highest stabilized conversion efficiency of 12.0% (Initial conversion-efficiency: 13.5%) was attained. Module reliability tests confirmed by IEC 61646 Ed. 2 revealed that the performance of the module is adapted. These high-performance a-Si/μc-Si tandem structure solar modules were prepared by using the knowledge of our thin-film and module technologies.
Toward stabilized 10% efficiency of large-area ( > 5000 cm2) a-Si/a-SiGe tandem solar cells using high-rate deposition
Abstract This paper reviews recent progress in large-area a-Si/a-SiGe tandem solar cells at Sanyo. Optimized hydrogen dilution conditions for high-rate deposition of hydrogenated amorphous silicon (a-Si:H) films and thinner i-layer structures have been systematically investigated for improving both the stabilized efficiency and the process throughput. As a result, a high photosensitivity of 10 6 for a-Si:H films has been maintained up to the deposition rate of 15 A/s. Furthermore, the world's highest initial conversion efficiency of 11.2% which corresponds to a stabilized efficiency of about 10% has been achieved for a 8252 cm 2 a-Si/a-SiGe tandem solar cell by combining the optimized hydrogen dilution and other successful technologies.
The Role of Hydrogen in the Staebler-Wronski Effect of a-Si:H
We have studied the effects of hydrogen concentration and hydrogen configuration on the light-induced change, called Staebler-Wronski effect, in a-Si:H. A strong correlation is found between the light-induced spin density and the fractional hydrogen content evolved at low annealing temperature. The light-induced defects are supposed to be created through the breaking of weak Si-Si bonds in the regions containing clustered SiH or SiH2 bonds.