Flexible micromorph tandem a-Si/{mu}c-Si solar cells
- Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering (IMT), Ecole Polytechnique Federale de Lausanne (EPFL), Rue A.-L. Breguet 2, CH-2000 Neuchatel (Switzerland)
The deposition of a stack of amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of {mu}c-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the {mu}c-Si:H cell and the light-induced degradation of the a-Si:H cell. As a result, {mu}c-Si:H cell has to grow on a smooth substrate with large periodicity (>1 {mu}m) and the a-Si:H cell on sharp pyramids with smaller feature size ({approx}350 nm) to strongly scatter the light in the weak absorption spectra of a-Si:H material. The asymmetric intermediate reflector introduced in this work uncouples the growth and light scattering issues of the tandem micromorph solar cells. The stabilized efficiency of the tandem n-i-p/n-i-p micromorph is increased by a relative 15% compared to a cell without AIR and 32% in relative compared to an a-Si:H single junction solar cells. The overall process (T<200 deg. C) is kept compatible with low cost plastic substrates. The best stabilized efficiency of a cell deposited on polyethylene-naphthalate plastic substrate is 9.8% after 1000 h of light soaking at V{sub oc}, 1 sun, and 50 deg. C.
- OSTI ID:
- 21476088
- Journal Information:
- Journal of Applied Physics, Vol. 107, Issue 1; Other Information: DOI: 10.1063/1.3275860; (c) 2010 American Institute of Physics; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTRA
AMORPHOUS STATE
CHEMICAL VAPOR DEPOSITION
CRYSTAL GROWTH
CRYSTALS
EFFICIENCY
HYDROGEN
LIGHT SCATTERING
POLYETHYLENES
SEMICONDUCTOR JUNCTIONS
SEMICONDUCTOR MATERIALS
SILICON SOLAR CELLS
SUBSTRATES
THIN FILMS
CHEMICAL COATING
DEPOSITION
DIRECT ENERGY CONVERTERS
ELEMENTS
EQUIPMENT
FILMS
MATERIALS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
POLYMERS
POLYOLEFINS
SCATTERING
SOLAR CELLS
SOLAR EQUIPMENT
SPECTRA
SURFACE COATING