Wide band-gap CuIn 1-XGa XSe 2 based chalcopyrite absorbers for tandem cell applications

Kushagra Nagaich, Stephen Campbell, Eray Aydil

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Device efficiencies of 20% have been achieved in CIGS-based chalcogenide absorbers, however progress has slowed in recent years. There has been a substantial interest in tandem cell structures to achieve a discrete jump in device efficiencies for these materials. Top cell absorbers with band-gap of 1.6 eV to 1.7 eV are the optimum choice for the wide band-gap top cell. CGS, CIGSS, CIAS and similar materials have all been investigated. However, for all of these materials the grain size decreases and the trap density rises sharply as the material approaches the required band-gap. This poses significant problems of interface recombination and increased bulk trap states which impede transport in the absorber. In this paper we propose a CIGS-based material developed by doping CIGS with moderate amount of aluminum (CIAGS) thus increasing the band-gap. A single step process with constant Cu, In, Ga, Al, Se fluxes has been used. The films are grown in the copper deficient regime throughout the deposition. Band-gap measurements were done by calculating the absorption coefficients using transmission spectroscopy. A substantial increase in the band-gap was observed for moderate amounts of Al and Ga in CIAGS films compared to CIGS. We investigated the grain structure of the films and find that moderate to large grains were observed, even for bandgaps as large as 1.5 eV.

Original languageEnglish (US)
Title of host publicationProgram - 37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Number of pages5
StatePublished - 2011
Event37th IEEE Photovoltaic Specialists Conference, PVSC 2011 - Seattle, WA, United States
Duration: Jun 19 2011Jun 24 2011

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Other37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Country/TerritoryUnited States
CitySeattle, WA

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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