The hot electron injection (HEI) effect has been widely applied in photocatalytic and photodetection systems; however, its efficiency is often low. Since the plasmonic response of every nanoparticle is the basis for the collective photocurrent results, it is imperative to examine the HEI processes at the single-particle level and to develop a theoretical model. Here, with the use of photoirradiated Kelvin probe force microscopy, the size effect of Au nanoparticles (AuNPs) was experimentally investigated at the single-particle level for the first time. Moreover, a comprehensive plasmonic injection model was developed to directly correlate the AuNP size to HEI efficiency. This theory captures the essential processes of hot electron generation and transport, and its results are consistent with the experimental measurements. Remarkably, the surface potential generated by the HEI is approximately linear to the nanoparticle diameter; the HEI current grows rapidly with increasing AuNP size, showing an increase of 3 orders of magnitude when the AuNP size varies from 10 to 60 nm; and the injection efficiency is inversely proportional to the particle size. This research may clarify plasmonic light harvesting processes for high-efficiency photocatalytic and photodetection systems.

中文翻译：

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单纳米粒子水平的尺寸依赖性热电子注入


热电子注入（HEI）效应在光催化和光电检测系统中得到了广泛的应用；然而，其效率往往较低。由于每个纳米粒子的等离子体响应是集体光电流结果的基础，因此有必要在单粒子水平上检查 HEI 过程并开发理论模型。在这里，通过使用光照射开尔文探针力显微镜，首次在单颗粒水平上对金纳米颗粒（AuNP）的尺寸效应进行了实验研究。此外，还开发了一种综合等离子体注入模型，将 AuNP 尺寸与 HEI 效率直接关联起来。该理论捕捉了热电子产生和传输的基本过程，其结果与实验测量结果一致。值得注意的是，HEI 产生的表面电势与纳米颗粒直径近似呈线性关系； HEI电流随着AuNP尺寸的增加而快速增长，当AuNP尺寸从10 nm变化到60 nm时，HEI电流增加了3个数量级；喷射效率与颗粒尺寸成反比。这项研究可能会阐明高效光催化和光电检测系统的等离子体光收集过程。