Al3 (A = As, Sb) Single Layers and Their vdW Heterostructure for Photocatalysis and Solar Cell Applications
Al3 (A = As, Sb) Single Layers and Their vdW Heterostructure for Photocatalysis and Solar Cell Applications
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DOI：
10.1021/acs.jpcc.8b01874
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发表时间：
2018-04-12
影响因子：
3.7
通讯作者：
Zhang, Wei-Bing
中科院分区：
文献类型：
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作者：
Lai, Kang;Yan, Chang-Lin;Zhang, Wei-Bing
二维(2D)层状材料及其范德华(VDW)异质结构是高效可再生能源应用的重要候选材料。在密度泛函理论的基础上，系统地研究了VA族三卤化物Al-3(A=As，Sb)单层及其VDW异质结的结构、稳定性、电学和光学性质。我们的结果表明，Al(3)(A=As，Sb)单层很容易从大块晶体中剥离，并且是动态稳定的。标准PBE理论预测了Al(3)的带隙随A元素个数的增加而增大，这与体相的实验结果相一致。当考虑自旋轨道耦合(SOC)效应时，这种不合理的趋势可以得到修正。PBE和PBE+SOC计算的不一致性可以通过晶格膨胀引起的能隙变化和相对论效应引起的两种相反效应的竞争来理解。我们的PBE+SOC计算表明，AsI_3和Sb_3单分子膜具有2.00和1.89 eV的间接禁带宽度和中等的电子迁移率(类似于10(2)cm(2)V~(-1)S(-1))，是潜在的光催化剂。通过垂直堆积AsI3和SbI3，可以形成具有II型能带排列的强束缚VDW异质结。令人兴奋的是，它的间接带隙降低到1.63 eV，绝对带边仍然跨越了水氧化还原电位，这意味着它可以作为一种对可见光有很强吸附的潜在光催化剂。此外，这种VDW异质结构还可以作为一种有效的激子太阳能电池材料，理论功率转换效率高达18%。这些结果表明，Al-3(A=As，Sb)单层及其VDW异质结构是未来太阳能转换应用的潜在候选者。
Two-dimensional (2D) layered materials and their van der Waals (vdW) heterostructures are promising candidates for highly efficient renewable energy application. On the basis of density functional theory, we investigated systematically the structure, stability, and electronic and optical properties of the group-VA trihalides Al-3 (A = As, Sb) single layers and their vdW heterostructure. Our results suggest that the AI(3) (A = As, Sb) single layers can be exfoliated from their bulk crystal easily and are also dynamically stable. Standard PBE predicts that the band gap of AI(3) increases with element number of A, which is in conflict with the experimental results of the bulk. This unreasonable trend can be corrected when the spin orbit coupling (SOC) effect is considered. The inconsistence between PBE and PBE+SOC calculations can be understood by the competition of two contrary effects for gap variation induced by lattice expansion and relativistic effect. Our PBE+SOC calculations indicate the AsI3 and SbI3 monolayers are potential photocatalysts for water splitting with indirect band gaps of 2.00 and 1.89 eV and moderate electron mobility (similar to 10(2) cm(2) V-1 s(-1)). By stacking AsI3 and SbI3 vertically, a strongly binding vdW heterostructure with a type-II band alignment can be formed. Excitingly, the indirect band gap is reduced to 1.63 eV, and the absolute band edges still straddle the water redox potentials, implying that it can be used as a potential photocatalyst with strong adsorption for visible light. Moreover, such a vdW heterostructure can also be an effective excitonic solar cell material with theoretical power conversion efficiency up to 18%. These results show that the Al-3 (A = As, Sb) single layers and their vdW heterostructure are potential candidates for future solar energy conversion applications.