Defect Tolerant Semiconductors for Solar Energy Conversion

Andriy Zakutayev, Christopher M. Caskey, Angela N. Fioretti, David S. Ginley, Julien Vidal, Vladan Stevanovic, Eric Tea, Stephan Lany

Research output: Contribution to journalArticlepeer-review

311 Scopus Citations

Abstract

Defect tolerance is the tendency of a semiconductor to keep its properties despite the presence of crystallographic defects. Scientific understanding of the origin of defect tolerance is currently missing. Here we show that semiconductors with antibonding states at the top of the valence band are likely to be tolerant to defects. Theoretical calculations demonstrate that Cu 3N with antibonding valence band maximum has shallow intrinsic defects and no surface states, in contrast to GaN with bonding valence band maximum. Experimental measurements indicate shallow native donors and acceptors in Cu3N thin films, leading to 1016-1017 cm-3 doping with either electrons or holes depending on the growth conditions. The experimentally measured bipolar doping and the solar-matched optical absorption onset (1.4 eV) make Cu3N a promising candidate absorber for photovoltaic and photoelectrochemical solar cells, despite the calculated indirect fundamental band gap (1.0 eV). These conclusions can be extended to other materials with antibonding character of the valence band, defining a class of defect-tolerant semiconductors for solar energy conversion applications.

Original languageAmerican English
Pages (from-to)1117-1125
Number of pages9
JournalJournal of Physical Chemistry Letters
Volume5
Issue number7
DOIs
StatePublished - 2014

NREL Publication Number

  • NREL/JA-5900-61368

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