Multi-phase back contacts for CIS solar cells
Multi-phase, single layer, non-interdiffusing M-Mo back contact metallized films, where M is selected from Cu, Ga, or mixtures thereof, for CIS cells are deposited by a sputtering process on suitable substrates, preferably glass or alumina, to prevent delamination of the CIS from the back contact layer. Typical CIS compositions include CuXSe{sub 2} where X is In or/and Ga. The multi-phase mixture is deposited on the substrate in a manner to provide a columnar microstructure, with micro-vein Cu or/and Ga regions which partially or fully vertically penetrate the entire back contact layer. The CIS semiconductor layer is then deposited by hybrid sputtering and evaporation process. The Cu/Ga-Mo deposition is controlled to produce the single layer two-phase columnar morphology with controllable Cu or Ga vein size less than about 0.01 microns in width. During the subsequent deposition of the CIS layer, the columnar Cu/Ga regions within the molybdenum of the Cu/Ga-Mo back layer tend to partially leach out, and are replaced by columns of CIS. Narrower Cu and/or Ga regions, and those with fewer inner connections between regions, leach out more slowly during the subsequent CIS deposition. This gives a good mechanical and electrical interlock of the CIS layer into the Cu/Ga-Mo back layer. Solar cells employing In-rich CIS semiconductors bonded to the multi-phase columnar microstructure back layer of this invention exhibit vastly improved photo-electrical conversion on the order of 17% greater than Mo alone, improved uniformity of output across the face of the cell, and greater Fill Factor. 15 figs.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-83CH10093
- Assignee:
- Rockett, A.A.; Yang, L.C.
- Patent Number(s):
- 5,477,088
- Application Number:
- 08/060,284
- OSTI ID:
- 170450
- Resource Relation:
- Patent File Date: 1993 May 12; Other Information: PBD: 19 Dec 1995
- Country of Publication:
- United States
- Language:
- English
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