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Title: Optoelectronic Properties of Strontium and Barium Copper Sulfides Prepared by Combinatorial Sputtering

Optically transparent materials with p-type electrical conductivity can facilitate the development of transparent electronics and improve the efficiency of photovoltaic solar cells. Sulfide materials represent an interesting alternative to oxides for these applications due to better hole transport properties. We prepare transparent and conductive Ba-Cu-S thin films by combinatorial cosputtering and characterized for their composition, structure, and optoelectronic properties. The conductivity and transparency of these films are found to be strongly dependent on their chemical composition and the substrate temperature during growth. The conductivity of BaCu 2S 2 and BaCu 4S 3 can reach 53 S/cm (at 250 °C) and 74 S/cm (at 200 degrees C), respectively, which is higher than their solution processed/bulk counterparts. The 90% reflectance corrected transmittance is achieved in the wavelength range 600-1000 nm for BaCu 2S 2 and 650-1000 nm for BaCu 4S 3 (at 250 °C). These electrical and optical properties are comparable with other recently presented transparent p-type conductors, while the 200-350 degrees C processing temperature is low enough to be used in semiconductor devices with limited thermal budgets. Some attempts have been made to synthesize the related Sr-Cu-S materials, following the theoretical suggestion of their potential as transparent p-type conductors, but thesemore » attempts resulted only in phase-separated SrS and CuxS phases. Alloying BaCu 2S 2 with Sr on the Ba site on the other hand increases the conductivity to >100 S/cm while only slightly compromising the transparency of the material. To explain the difference between the Ba and the Sr containing copper sulfides, the lower bounds on the SrCu 2S 2 and SrCu 4S 3 formation enthalpies are estimated. While the doping of the Ba-Cu-S materials presented here is too large for application in transparent electronics, it is promising for potential use as p-type contact layers in thin film solar cells.« less
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [2]
  1. Fudan Univ., Shanghai (China). Dept. of Materials Science; National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Fudan Univ., Shanghai (China). Dept. of Materials Science
Publication Date:
Report Number(s):
Journal ID: ISSN 0897-4756
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 19; Journal ID: ISSN 0897-4756
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Next Generation of Materials by Design: Incorporating Metastability (CNGMD)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; photovoltaics; transparent electronics; optoelectronic properties
OSTI Identifier: