Significant Reduction in NiO Band Gap Upon Formation of LixNi1-xO alloys: Applications To Solar Energy Conversion
Significant Reduction in NiO Band Gap Upon Formation of LixNi1-xO alloys: Applications To Solar Energy Conversion
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DOI：
10.1002/cssc.201300595
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发表时间：
2014-01-01
期刊：
影响因子：
8.4
通讯作者：
Carter, Emily A.
中科院分区：
文献类型：
--
作者：
Alidoust, Nima;Toroker, Maytal Caspary;Carter, Emily A.
长期可持续的太阳能转换依赖于识别具有用于光伏和光催化应用的适当能带结构的经济且通用的半导体材料（例如，带隙类似于1.5- 2.0eV）。氧化镍（NiO）是一种廉价但非常有前途的候选物。其电荷转移特性可能导致更高效率所需的更长载流子寿命，并且其导带边缘适合于通过水裂解驱动氢析出。然而，NiO的大带隙（类似于4 eV）严重限制了其在实际应用中的使用。我们的第一性原理量子力学计算表明，当NiO与Li 2 O合金化时，带隙急剧减小至2.0 eV。我们发现，LixNi 1-xO合金（x=0.125和0.25）是p型半导体，包含的状态，在差距没有杂质水平，并保持NiO的理想的电荷转移字符。最后，我们表明，该合金具有潜在的光电化学应用，与带边以及放置在光催化制氢和CO2还原，以及在串联染料敏化太阳能电池作为光电阴极。
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 similar to 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 (similar to 4 eV) severely limits its use in practical applications. Our first-principles quantum mechanics calculations show band gaps dramatically decrease to similar to 2.0 eV when NiO is alloyed with Li2O. We show that LixNi1-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.