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Title: Structure and interface chemistry of MoO{sub 3} back contacts in Cu(In,Ga)Se{sub 2} thin film solar cells

Molybdenum oxide (MoO{sub 3}) is considered as a possible primary back contact for Cu(InGa)Se{sub 2} thin film solar cells for its potential as a transparent back contact for superstrate and bifacial devices. MoO{sub 3} films were deposited on Mo or ITO-coated soda lime glass substrates by reactive rf sputtering in an ambient of Ar + O{sub 2} with O{sub 2}/(O{sub 2} + Ar) = 35% on which Cu(In{sub 0.7}Ga{sub 0.3})Se{sub 2} alloy absorber layers were deposited using multi-source elemental evaporation. Scanning Electron Microscopy studies showed uniform coverage of the as-deposited MoO{sub 3} layer and good adhesion was obtained in all cases. X-ray Photoelectron Spectroscopy depth profile analysis showed that MoSe{sub 2} was not formed at the Cu(InGa)Se{sub 2} interface with either the Mo-MoO{sub 3} or ITO-MoO{sub 3} back contacts. Determination of the valence band offsets showed that the MoO{sub 3} layer at the interface changes the energy band alignment with Cu(InGa)Se{sub 2}, producing a primary contact with lower valence band offset than ITO. Cu(In,Ga)Se{sub 2} thin film solar cells prepared using an as-deposited Mo-MoO{sub 3} back contact yielded a best conversion efficiency of 14%, with V{sub OC} = 647 mV, J{sub SC} = 28.4 mA/cm{sup 2}, and FF = 78.1%. Cells with ITO-MoO{sub 3} back contact showed a best efficiency of 12%, with V{submore » OC} = 642 mV, J{sub SC} = 26.8 mA/cm{sup 2}, and FF = 69.2%.« less
Authors:
;  [1] ;  [2] ; ;  [1]
  1. Institute of Energy Conversion, University of Delaware, Newark, Delaware 19716 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22275699
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COPPER SELENIDES; ENERGY EFFICIENCY; EVAPORATION; GALLIUM SELENIDES; INDIUM SELENIDES; INTERFACES; LAYERS; MOLYBDENUM OXIDES; MOLYBDENUM SELENIDES; SCANNING ELECTRON MICROSCOPY; SOLAR CELLS; SPUTTERING; SUBSTRATES; THIN FILMS; VALENCE; X-RAY PHOTOELECTRON SPECTROSCOPY