Local Built-in Potential on Grain Boundary of Cu(In,Ga)Se2 Thin Films

Research output: Contribution to conferencePaper

Abstract

We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In,Ga)Se2 (CIGS) thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy (SKPM). The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates theexistence of a local built-in potential on GBs and that the GB is positively charged. The role of the built-in potential in device performance was further examined by tuning Ga content or band gap of the film. With increasing Ga content, the GB potential drops sharply in a Ga range of 28%~38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversionefficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage CIGS device.
Original languageAmerican English
Number of pages5
StatePublished - 2005
Event2004 DOE Solar Energy Technologies Program Review Meeting - Denver, Colorado
Duration: 25 Oct 200428 Oct 2004

Conference

Conference2004 DOE Solar Energy Technologies Program Review Meeting
CityDenver, Colorado
Period25/10/0428/10/04

Bibliographical note

Presented at the 2004 DOE Solar Energy Technologies Program Review Meeting, 25-28 October 2004, Denver, Colorado. Also included in the proceedings available on CD-ROM (DOE/GO-102005-2067; NREL/CD-520-37140)

NREL Publication Number

  • NREL/CP-520-36981

Keywords

  • devices
  • direct measurement
  • grain boundaries (GBS)
  • photoconversion
  • PV
  • scanning Kelvin probe microscopy (SKPM)
  • thin films
  • three-stage

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