Mechanism of In-Plane and Out-of-Plane Tribovoltaic Direct-Current Transport with a Metal/Oxide/Metal Dynamic Heterojunction
Mechanism of In-Plane and Out-of-Plane Tribovoltaic Direct-Current Transport with a Metal/Oxide/Metal Dynamic Heterojunction
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DOI：
10.1021/acsami.1c22438
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发表时间：
2022-01-06
影响因子：
9.5
通讯作者：
Liu, Jun
中科院分区：
文献类型：
--
作者：
Benner, Matthew;Yang, Ruizhe;Liu, Jun
界面层工程已被证明是一种有效的策略，用于提高基于晶闸管的动态直流（DC）发电机的功率输出，虽然功率增强的潜在机制仍然不清楚。在这里，通过比较由原子层沉积（ALD）制备的原型金属-氧化物-金属异质结的基本摩擦伏打DC输出特性和垂直沉积（CVD）制备的原型金属-氧化物-金属异质结的基本摩擦伏打DC输出特性，（通过界面层的面外载流子输运）和水平方向的载流子输运。（沿界面层沿着面内载流子传输）配置，使非平衡电子激发和界面电容放大的影响，可以单独调谐和调查。在Al/TiO 2/Ti垂直结构中，随着TiO 2厚度（t（TiO 2））从0增加到200 nm，开路电压（V-OC）从-0.03 V线性增加到-0.52 V，线性放大系数为-2.31 mV nm（-1）。相比之下，具有水平配置的V-OC输出类似于55 mV，其中电位差仅与耗尽区中的表面电荷的积累和随后的电荷重排相关联。同时，测量到短路电流密度（JSC）随着t（TiO 2）的增加而显示出初始增加趋势，在t（TiO 2）= 20 nm时在0.21 A m（-2）处达到其峰值，然后随着t（TiO 2）的进一步增加而减小。从电流-电压（I-V）特性，它提出了这样的DC输出变化与最佳的界面层厚度源于放大电压和增加的电阻随着界面层厚度的增加，与主要的电荷传输机制从量子隧穿切换到电子发射/陷阱辅助运输的竞争。与此相反，摩擦伏打激发被证明是显着较弱的宽带隙绝缘体（Al 2 O 3）时，涉及。阐明了界面层增强功率的基本机理，对高性能直流纳米发电机的开发和优化具有重要的指导意义。
Interfacial layer engineering has been demonstrated as an effective strategy for boosting power output in semiconductor-based dynamic direct-current (DC) generators, although the underlying mechanism of power enhancement remains obscure. Here, such ambiguity has been elucidated by comparing fundamental tribovoltaic DC output characteristics of prototypical metal-oxide-metal heterojunctions prepared by atomic-layer deposition (ALD) with a vertical (out-of-plane carrier transport through the interfacial layer) and a horizontal (inplane carrier transport along the interfacial layer) configuration such that the influences from nonequilibrium electronic excitation and interfacial capacitive amplification can be individually tuned and investigated. It is found in the case of Al/TiO2/Ti vertical configurations that the open-circuit voltage (V-OC) increases linearly from -0.03 to -0.52 V as the thickness of titanium oxide (t(TiO2)) increases from 0 to 200 nm with a linear amplification coefficient of -2.31 mV nm(-1), which is validated by a parallel-capacitor theoretical model with tribovoltaic electronic excitation. In contrast, the V-OC output with the horizontal configuration is similar to 55 mV, where the potential difference is merely associated with the accumulation of surface charges and the subsequent charge rearrangement in the depletion region. Meanwhile, it is measured that the short-circuit current density (JSC) shows an initial increasing trend when t(TiO2) increases, reaches its peak value at 0.21 A m(-2) at t(TiO2) = 20 nm, and then decreases as t(TiO2) increases further. From current-voltage (I-V) characterization, it is proposed that such DC output variation with an optimal interfacial layer thickness stems from the competition of amplified voltage and increased resistance with increasing interfacial layer thickness, with the main charge transport mechanism switching from quantum tunneling to thermionic emission/trap-assisted transport. In contrast, tribovoltaic excitation is proven to be significantly weaker when a wide band-gap insulator (Al2O3) is involved. The elucidation of the fundamental mechanism of power enhancement by the interfacial layer in this work is of great significance in providing instructional direction for the development and optimization of high-performance DC nanogenerators.