Significant Reduction in NiO Band Gap Upon Formation of Li_xNi_1-xO alloys: Applications To Solar Energy Conversion

Journal Article · Thu Nov 21 00:00:00 EST 2013 · ChemSusChem

DOI:https://doi.org/10.1002/cssc.201300595· OSTI ID:1120081

Alidoust, Nima; Toroker, Maytal Caspary; Keith, John A.; Carter, Emily A.

Long-term sustainable solar energy conversion relies on identifying economical and versatile semiconductor materials with appropriate band structures for photovoltaic and photocatalytic applications (e.g., band gaps of ~1.5–2.0 eV). Nickel oxide (NiO) is an inexpensive yet highly promising candidate. Its charge-transfer character may lead to longer carrier lifetimes needed for higher efficiencies, and its conduction band edge is suitable for driving hydrogen evolution via water-splitting. However, NiO’s large band gap (~4 eV) severely limits its use in practical applications. Our first-principles quantum mechanics calculations show band gaps dramatically decrease to ~2.0 eV when NiO is alloyed with Li₂O. In this paper, we show that Li_xNi_1-xO alloys (with x=0.125 and 0.25) are p-type semiconductors, contain states with no impurity levels in the gap and maintain NiO’s desirable charge-transfer character. Lastly, we show that the alloys have potential for photoelectrochemical applications, with band edges well-placed for photocatalytic hydrogen production and CO₂ reduction, as well as in tandem dye-sensitized solar cells as a photocathode.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1120081
• Journal Information: ChemSusChem, Vol. 7, Issue 1; ISSN 1864-5631
• Publisher: ChemPubSoc Europe
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory