U.S. Department of Energy - Energy Efficiency and Renewable Energy

Solar Energy Technologies Program

Thin Films: Copper Indium Diselenide (CIS)

Photo of a CIS Thin-film array.

The laboratory research promise of CIS thin-film cells is proving true. This 1 kW array, comprising 28 CIS modules from Siemens Solar Industries, is the highest-efficiency thin-film array to date (averaging 11.5% efficiency at Standard Test Conditions). The modules, winners of an R&D 100 Award in 1999, are being monitored at NREL for long-term performance and reliability.

Copper indium diselenide (CIS), after two decades of R&D, is being introduced to the market, with prototype modules reaching efficiencies greater than 11%. CIS is also enjoying success in the laboratory, with cell efficiencies climbing to a world-record 19.2% at NREL.

Research on CIS focuses on several of today's challenges:

  • Pushing efficiencies even higher by exploring the chemistry and physics of the junction formation and by examining concepts to allow more of the high-energy part of the solar spectrum to reach the absorber layer.

  • Dropping costs and facilitating the transition to a commercial stage by increasing the yield of CIS modules—which means increasing the percentage of modules and cells that make it intact through the manufacturing process.

  • Decreasing manufacturing complexity and cost, and improving module packaging.

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