Stacking Independence and Resonant Interlayer Excitation of Monolayer WSe 2 /MoSe 2 Heterostructures for Photocatalytic Energy Conversion
Stacking Independence and Resonant Interlayer Excitation of Monolayer WSe 2 /MoSe 2 Heterostructures for Photocatalytic Energy Conversion
复制标题
用于光催化能量转换的单层WSe 2 /MoSe 2 异质结构的堆叠独立性和共振层间激发
DOI：
10.1021/acsanm.9b01898
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发表时间：
2020
影响因子：
5.9
通讯作者：
Cronin, Stephen B.
中科院分区：
文献类型：
--
作者：
Chen, Jihan;Bailey, Connor S.;Cui, Dingzhou;Wang, Yu;Wang, Bo;Shi, Haotian;Cai, Zhi;Pop, Eric;Zhou, Chongwu;Cronin, Stephen B.
我们报道了WSe 2-on-MoSe 2和MoSe 2-on-WSe 2异质结构的光催化性能的比较。虽然由于这两种材料之间的能带偏移，在这些异质结构中存在大约100 kV/cm的内置电场，但是光催化性能（即，光电流）与两种材料的堆叠顺序无关。在这些条件下求解泊松方程，我们发现异质结构中产生的内建电场比电化学双层中产生的内建电场小至少1个数量级（即，Helmholtz层）。Mott-Schottky测量表明，ITO电极上的过渡金属二硫属化物（TMDC）具有与裸ITO类似的电容，进一步证明了固态异质结构中产生的界面电场与溶液中离子产生的电场相比可以忽略不计。这些异质结构的光催化性能提供了最大的相对增强的异质结区域下920和785 nm的照射相比，532和633 nm波长的激发。在这里，920 nm（1.35 eV）的光子位于带隙以下，并在构成单层材料中产生非常小的光电流，但共振激发异质结构中的层间光学跃迁，在测量的光电流中产生5倍的增强。
We report a comparison of the photocatalytic performance of WSe2-on-MoSe2and MoSe2-on-WSe2heterostructures. While built-in electric fields exist in these heterostructures on the order of 100 kV/cm due to band offsets between these two materials, the photocatalytic performance (i.e., photocurrent) is independent of the stacking order of the two materials. Solving Poisson’s equation under these conditions, we find that the built-in electric field produced in the heterostructure is at least 1 order of magnitude smaller than that produced in the electrochemical double layer (i.e., Helmholtz layer). Mott–Schottky measurements indicate that transition metal dichalcogenides (TMDCs) on ITO electrodes have similar capacitance to that of bare ITO, providing further evidence that the interfacial electric fields produced in the solid state heterostructure are negligible compared to the fields generated by the ions in solution. The photocatalytic performance of these heterostructures provided the largest relative enhancement in the heterojunction region under 920 and 785 nm irradiation compared with 532 and 633 nm wavelength excitation. Here, the 920 nm (1.35 eV) photons lie below the band gaps and produce very little photocurrent in the constituent monolayer materials but resonantly excite the interlayer optical transition in the heterostructure, producing a 5-fold enhancement in the measured photocurrent.