The a-Si:H/poly-Si Heterojunction Solar Cells

  • Kim, Sang-Su (Dept. of Electrical Engineering, Sung Kyun Kwan University) ;
  • Kim, do-Young (Dept. of Electrical Engineering, Sung Kyun Kwan University) ;
  • Lim, Dong-Gun (Dept. of Electrical Engineering, Sung Kyun Kwan University) ;
  • Junsin Yi (Dept. of Electrical Engineering, Sung Kyun Kwan University) ;
  • Lee, Jae-Choon (Research and Development Center, LG Siltron) ;
  • Lim, Koeng-Su (Dept. of Electrical Engineering, KAIST)
  • Published : 1997.10.01

Abstract

We present heterojunction solar cells with a structure of metal/a-Si:H(n-i-p)/poly-Si(n-p)/metal for the terrestrial applications. This cell consists fo two component cells: a top n-i-p junction a-Si:Hi cell with wide-bandgap 1.8eV and a bottom n-p junction poly-Si cell with narrow-bandgap 1.1eV. The efficiency influencing factors of the solar cell were investigated in terms of simulation an experiment. Three main topics of the investigated study were the bottom cell with n-p junction poly-Si, the top a-Si:H cell with n-i-p junction, and the interface layer effects of heterojunction cell. The efficiency of bottom cell was improved with a pretreatment temperature of 900$^{\circ}C$, surface polishing, emitter thickness of 0.43$\mu\textrm{m}$, top Yb metal, and grid finger shading of 7% coverage. The process optimized cell showed a conversion efficiency about 16%. Top cell was grown by suing a photo-CVD system which gave an ion damage free and good p/i-a-Si:H layer interface. The heterojunction interface effect was examined with three different surface states; a chemical passivation, thermal oxide passivation, and Yb metal. the oxide passivated cell exhibited the higher photocurrent generation and better spectral response.

Keywords

References

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