Hole Transport in Nonstoichiometric and Doped Wüstite

Journal Article · Thu Aug 23 04:00:00 EDT 2012 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/jp3047664· OSTI ID:1053368

Toroker, Maytal Caspary; Carter, Emily A.

We propose ways to enhance the conductivity of wustite (i.e., naturally p-type FeO), a visible-light-absorbing, inexpensive, abundant, and nontoxic potential alternative material for solar energy conversion devices. Unfortunately, the conversion efficiency of FeO is inhibited by its low hole conductivity. Increasing the iron vacancy concentration or adding p-type dopants improves FeO conductivity by increasing the number of holes; however, it is not known which strategy introduces larger energy traps that would hinder hole conductivity. Here we employ the small polaron model along with ab initio calculations on electrostatically embedded clusters to analyze the local trapping effects of iron vacancies and several substitutional p-type dopants that are soluble in FeO, including copper, nitrogen, lithium, and sodium, and also hydrogen as an interstitial dopant for comparison. We find that vacancies create stronger traps than dopants and that copper and nitrogen dopants form deeper traps than lithium, sodium, or hydrogen. Furthermore, hydrogen repels the hole and substantially decreases the trap formed by an iron vacancy. Because of the shallower traps formed compared to vacancies, lithium-, sodium-, or hydrogen-doped, nanostructured or alloyed FeO may be worth evaluating as a p-type semiconductor for solar energy conversion applications.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1053368
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 33 Vol. 116; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Environmental Molecular Sciences Laboratory