Photovoltaic Properties of Selenized CuGa/In Films with Varied Compositions

Lorelle Mansfield, Christopher Muzzillo, Kannan Ramanathan, J. McGoffin, Timothy Anderson

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations

Abstract

Thin CuGa/In films with varied compositions were deposited by co-evaporation and then selenized in situ with evaporated selenium. The selenized Cu(In, Ga)Se2 absorbers were used to fabricate 390 solar cells. Cu/(Ga+In) and Ga/(Ga+In) (Cu/III and Ga/III) were independently varied, and photovoltaic performance was optimal at Cu/III of 77-92% for all Ga/III compositions studied (Ga/III ∼ 30, 50, and 70%). The best absorbers at each Ga/III composition were characterized with time-resolved photoluminescence, scanning electron microscopy, and secondary ion mass spectrometry, and devices were studied with temperature-dependent current density-voltage, light and electrical biased quantum efficiency, and capacitance-voltage. The best cells with Ga/III ∼ 30, 50, and 70% had efficiencies of 14.5, 14.4, and 12.2% and maximum power temperature coefficients of -0.496, -0.452, and -0.413%/°C, respectively. This resulted in the Ga/III ∼ 50% champion having the highest efficiency at temperatures greater than 40°C, making it the optimal composition for practical purposes. This optimum is understood as a result of the absorber's band gap grading - where minimum band gap dominates short-circuit current density, maximum space charge region band gap dominates open-circuit voltage, and average absorber band gap dominates maximum power temperature coefficient.

Original languageAmerican English
Pages2236-2241
Number of pages6
DOIs
StatePublished - 18 Nov 2016
Event43rd IEEE Photovoltaic Specialists Conference, PVSC 2016 - Portland, United States
Duration: 5 Jun 201610 Jun 2016

Conference

Conference43rd IEEE Photovoltaic Specialists Conference, PVSC 2016
Country/TerritoryUnited States
CityPortland
Period5/06/1610/06/16

Bibliographical note

Publisher Copyright:
© 2016 IEEE.

NREL Publication Number

  • NREL/CP-5K00-67960

Keywords

  • chalcopyrite
  • CIGS
  • Cu(In, Ga)Se
  • graded band gap
  • selenization
  • temperature coefficient

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