Role of the Interface between Ag and ZnO in the Electric Conductivity of Ag Nanoparticle-Embedded ZnO
Role of the Interface between Ag and ZnO in the Electric Conductivity of Ag Nanoparticle-Embedded ZnO
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DOI：
10.1021/acsami.9b17922
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发表时间：
2020-01-29
影响因子：
9.5
通讯作者：
Lee, Jung-Kun
中科院分区：
文献类型：
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作者：
Huang, Po-Shun;Qin, Fen;Lee, Jung-Kun
将平均尺寸为30 nm的Ag纳米颗粒（Ag NPs）添加到ZnO中，使电导率增加高达1000倍。虽然在Ag纳米颗粒和Al掺杂的ZnO（AZO）膜的混合物中观察到电导率的类似增加，但是对于添加Ag NP的ZnO和添加Ag NP的AZO，电导率变化的物理机制是不相同的。在添加Ag NP的ZnO中，在ZnO-Ag界面处形成欧姆结，并且电子在ZnO-Ag界面附近的ZnO中积累，直到富电子岛连接。然而，在添加Ag NP的AZO中，Ag NP中的电子通过电子发射移动到AZO基质并穿过AZO基质。在ZnO-Ag和AZO-Ag界面处的电子输运的这种变化是由于ZnO的功函数（4.62 eV）大于Ag的功函数（4.24 eV）和AZO的功函数（4.15 eV）。ZnO基体中Ag NP含量的增加导致电子聚集区的重叠，并形成电子输运的渗滤路径，而不恶化电子迁移率。因此，在添加有1.4体积% Ag NP的ZnO膜中，电子浓度增加到2.4 × 10（20）/cm（3）。此外，Ag NP对透射率的影响可以忽略不计，并且ZnO：Ag NP和AZO：Ag NP的最佳Haacke优值（Phi（H））值分别为2.86和5.18。
The addition of Ag nanoparticles (Ag NPs) with an average size of 30 nm into ZnO increases the electric conductivity up to 1000 times. While a similar increase in the conductivity is observed in a mixture of Ag nanoparticles and Al-doped ZnO (AZO) films, a physical mechanism underlying the change in electric conductivity is not the same for Ag NP-added ZnO and Ag NP-added AZO. In Ag NP-added ZnO, an ohmic junction is formed at the ZnO-Ag interface, and electrons are accumulated in ZnO near the ZnO-Ag interface until electron-rich islands are connected. However, in Ag NP-added AZO, electrons in Ag NPs move to the AZO matrix via thermionic emission and travel through the AZO matrix. This change in electron transport at ZnO-Ag and AZO-Ag interfaces is due to the fact that the work function of ZnO (4.62 eV) is larger than those of Ag (4.24 eV) and AZO (4.15 eV). An increase in Ag NP content in the ZnO matrix leads to the overlap of the electron accumulation regions and forms a percolation path for the electron transport without deteriorating the electron mobility. Hence, the electron concentration increases to 2.4 X 10(20)/cm(3) in the 1.4 vol % Ag NP-added ZnO film. In addition, Ag NPs have a negligible effect on the transmittance, and the best Haacke figure of merit (Phi(H)) values are 2.86 and 5.18 for ZnO:Ag NP and AZO:Ag NP, respectively.