The optimal band gap for a semiconductor in photovoltaic (PV) and photocatalytic (PC) devices is ~1.5-2.0 eV. Additionally, for PC applications the band edges must be suitably placed to ensure that the desired electrochemical reactions are thermodynamically favorable. Nickel oxide (NiO) is an inexpensive candidate for use in PV and PC. Its charge-transfer character may lead to longer carrier lifetimes and higher efficiencies. However, its band gap (~4 eV) is too large. We propose to alloy NiO with Li2O to lower this gap. We use density functional theory + U to determine that no impurity levels are formed in the gap for LixNi1-xO alloys with x=0.125 and 0.25. We perform G0W0 quasiparticle calculations to show that these alloys are charge-transfer semiconductors with optimal band gaps for PV and PC. We further show that their band edges are well-placed for PC hydrogen production.

Band gap engineering of nickel(II) oxide via degenerate alloying with Li<sub>2</sub>O for solar energy conversion: A theoretical study

245th National Meeting (2013)

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Band gap engineering of nickel(II) oxide via degenerate alloying with Li2O for solar energy conversion: A theoretical study

Band gap engineering of nickel(II) oxide via degenerate alloying with Li₂O for solar energy conversion: A theoretical study