Back to Search
Start Over
Gallium gradients in Cu(In,Ga)Se2 thin-film solar cells.
- Source :
- Progress in Photovoltaics; Jun2015, Vol. 23 Issue 6, p717-733, 16p
- Publication Year :
- 2015
-
Abstract
- The gallium gradient in Cu(In,Ga)Se<subscript>2</subscript> (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co-evaporation processes, plays a key role in the device performance of CIGS thin-film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X-ray measurements. In addition, the gallium grading of a CIGS layer grown with an in-line co-evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth-dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co-evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi-Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross-sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper-vacancy-mediated indium and gallium diffusion in CuInSe<subscript>2</subscript> and CuGaSe<subscript>2</subscript> were calculated using density functional theory. The migration barrier for the In<subscript>Cu</subscript> antisite in CuGaSe<subscript>2</subscript> is significantly lower compared with the Ga<subscript>Cu</subscript> antisite in CuInSe<subscript>2</subscript>, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co-evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Subjects :
- GALLIUM compounds
SOLAR cells
SOLAR batteries
PHOTOVOLTAIC cells
MASS spectrometry
Subjects
Details
- Language :
- English
- ISSN :
- 10627995
- Volume :
- 23
- Issue :
- 6
- Database :
- Complementary Index
- Journal :
- Progress in Photovoltaics
- Publication Type :
- Academic Journal
- Accession number :
- 102202738
- Full Text :
- https://doi.org/10.1002/pip.2485