The problem of the top cell for the micromorph tandem
A detailed study of the influence of different materials for the amorphous top cell on the stabilized efficiency of amorphous silicon/microcrystalline silicon (micromorph) tandem cells is presented. The authors investigate different amorphous i-layer materials which are applied in cells with varying thicknesses. It is shown that it is preferable to optimize the top cell in order to obtain a high current rather than a high voltage. A simple optical and electrical model is presented which allows one to predict the optimum optical bandgap of the i-layer material of the top cell and to determine its optimum thickness for maximum stabilized efficiency. By means of this model it is shown that the optimum top cell for a total cell current of 26 mA/cm{sup 2} should contain about 2,500 {angstrom} thick i-layer with an optical gap E{sub 04} {approx} 1.8 eV. The model furthermore shows that it is desirable to obtain slightly bottom-limited conditions after degradation in order to maximize the output power. A stabilized efficiency of 10.7% for a micromorph tandem cell has been confirmed by an independent measurement (FhG-ISE). Another such cell yields a stabilized efficiency of 11.2% as measured in their laboratory.
- Research Organization:
- Univ. de Neuchatel (CH)
- Sponsoring Organization:
- Swiss Federal Department of Energy
- OSTI ID:
- 20085551
- Resource Relation:
- Conference: Amorphous and Microcrystalline Silicon Technology - 1997, San Francisco, CA (US), 03/31/1997--04/04/1997; Other Information: PBD: 1997; Related Information: In: Amorphous and microcrystalline silicon technology--1997. Materials Research Society symposium proceedings, Volume 467, by Wagner, S.; Hack, M.; Schiff, E.A.; Schropp, R.; Shimizu, I. [eds.], 999 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
The {open_quotes}Micromorph{close_quotes} cell: a new way to high-efficiency-low-temperature crystalline silicon thin-film cell manufacturing?
Flexible micromorph tandem a-Si/{mu}c-Si solar cells