WSe2—a layered semiconductor that can be exfoliated into atomically thin two-dimensional sheets—offers promising characteristics for application in solar energy conversion. However, the lack of controllable, cost-effective methods to scalably fabricate homogeneous thin films currently limits practical application. Here we present a technique to prepare controlled thin films of 2D WSe2 from dispersions of solvent-exfoliated few-layer flakes. Flake self-assembly at a liquid/liquid interface (formed exceptionally from two non-solvents for WSe2) followed by substrate transfer affords large-area thin films with superior 2D flake alignment compared with traditional (liquid/air) self-assembly techniques. We further demonstrate, for the first time, solar-to-hydrogen conversion from solution-processed WSe2 thin films. Bare photoelectrodes with a thickness of ca. 25 nm exhibit sustained p-type photocurrent under simulated solar illumination, and up to 1.0 mA cm–2 at 0 V versus reversible hydrogen electrode with an added water reduction catalyst (Pt). The importance of the self-assembled morphology is established by photoelectrochemical and conductivity measurements.
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机译:WSe2是一种可以剥落成原子薄的二维片的分层半导体,具有在太阳能转换中应用的广阔前景。然而,目前缺乏可控的,成本有效的方法来可规模地制造均质薄膜,这限制了实际应用。在这里,我们提出一种从溶剂剥落的几层薄片的分散液中制备2维WSe2受控薄膜的技术。与传统的(液体/空气)自组装技术相比,在液体/液体界面处的薄片自组装(由两种非WSe2的非溶剂形成),然后进行基板转移,可提供大面积的薄膜,并具有出色的2D薄片排列。我们进一步首次证明了溶液处理的WSe2薄膜的太阳能转化为氢。裸光电电极的厚度约为25 nm在模拟太阳光照下表现出持续的p型光电流,与添加了减水催化剂(Pt)的可逆氢电极相比,0 V时高达1.0 sustainedmA cm –2 sup>。通过光电化学和电导率测量确定了自组装形态的重要性。
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