Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. Here, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm² photocurrents at the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ∼1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ∼60 μA/cm² water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.

中文翻译：

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超薄金属氧化物钝化改善固溶处理有机半导体薄膜上可见光电化学水分解的稳定性和性能

可溶液处理的有机半导体由于其可调节的小带隙和电子能级而具有作为可见光电化学（PEC）分解水电极的潜力，但它们通常受到稳定性和光催化活性的限制。在这里，我们演示了通过超薄金属氧化物钝化层提高了稳定性和性能的固溶有机半导体薄膜上的直接可见PEC水氧化。通过原子层沉积被亚2 nm ZnO钝化的N型富勒烯衍生物薄膜，在苛刻的碱性电解质环境中，波长大于600 nm的可见PEC水氧化作用高达30μA/ cm ²在热力学水氧化平衡电势下的光电流和光阳极的半衰期延长至约1000 s。系统研究表明，ZnO钝化作用增强了水氧化催化活性，而电荷隧穿控制了通过钝化层的空穴传输。通过改善与有机半导体的底部欧姆接触，可实现进一步增强的PEC性能，达到约60μA/ cm ²平衡电位下的水氧化光电流，据我们所知是有机半导体薄膜的最高值。钝化有机光电极的改进的稳定性和性能以及发现的设计原理为基于有机半导体薄膜实现稳定的可见光太阳能PEC水分解提供了有用的指导。