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Exact field solution to guided wave propagation in lossy thin films
James R Nagel1, Steve Blair, Michael A Scarpulla
1Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, USA. nageljr@ieee.org
Optics Express
|October 15, 2011
Summary
This study models electromagnetic wave propagation in thin film solar cells, revealing new loss-guided and anti-guided modes. These findings improve understanding of light trapping in photovoltaics.
Area of Science:
- Optics and Photonics
- Materials Science
- Renewable Energy
Background:
- Wave guidance is crucial for light trapping in thin film photovoltaics.
- Accurate modeling of optical loss effects on field profiles is essential for device efficiency.
Purpose of the Study:
- To derive the full-field solution for electromagnetic wave propagation in a symmetric dielectric slab with finite absorption.
- To investigate the impact of material loss on wave propagation modes and their relevance to thin film solar cells.
Main Methods:
- Derived the full-field solution for electromagnetic wave propagation in a lossy dielectric slab.
- Analyzed the eigenvalue equation, noting complex propagation constants.
- Developed an approximate solution for the longitudinal attenuation coefficient using geometric optics.
Main Results:
- The eigenvalue equation's functional form remains identical to the lossless case, but with complex propagation constants.
- Introduced novel loss-guidance and anti-guidance modes not present in lossless models.
- The approximate solution for attenuation coefficient shows excellent agreement with the exact value.
Conclusions:
- Finite absorption in dielectric slabs introduces new wave propagation modes.
- The derived model accurately describes lossy mode propagation, applicable to amorphous silicon thin film solar cells.
- Understanding these lossy modes can enhance light trapping strategies in photovoltaic devices.
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