CuTaS3: Intermetal d-d Transitions Enable High Solar Absorption

Liping Yu, Jaeseok Heo, Emmeline Altschul, Benjamin Waters, John Wager, Alex Zunger, Douglas Keszler

Research output: Contribution to journalArticlepeer-review

23 Scopus Citations


To realize the fundamental limits of photovoltaic device efficiency, solar absorbers must exhibit strong absorption and abrupt absorption onsets. Ideally, onsets to maximum absorption (a > 105 cm-1) occur over a few tenths of an electronvolt. First-principles calculations predict CuTaS3 represents a potentially new class of materials with such absorption characteristics. Narrow metallic d bands in both the initial and final states present high joint densities of states and, therefore, strong absorption. Specifically, a mixture of metal d (Cu1+, d10) and S p characterizes states near the valence band maximum, and metal d (Ta5+, d0) dominates near the conduction band minimum. Optical absorption measurements on thin films confirm the abrupt onset to strong absorption a > 105 cm-1 at Eg + 0.4 eV (Eg = 1.0 eV). Theoretical CuTaS3 solar cell efficiency is predicted to be 28% for a 300 nm film based on the metric of spectroscopic limited maximum efficiency, which exceeds that of CuInSe2. This sulfide may offer new opportunities to discover and develop a new class of mixed d-element solar absorbers.
Original languageAmerican English
Pages (from-to)2594-2598
Number of pages5
JournalChemistry of Materials
Issue number6
StatePublished - 2017

NREL Publication Number

  • NREL/JA-5900-68392


  • photovoltaic device efficiency
  • solar absorbers
  • solar cells


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