Tribovoltaic effect
The tribovoltaic effect is a type of triboelectric current where a direct-current (DC) current is generated by sliding a P-type semiconductor on top of a N-type semiconductor or a metal surface without the illumination of photons, which was firstly proposed by Wang et al.[1] in 2019 and later observed experimentally in 2020. When a P-type semiconductor slides over a N-type semiconductor, electron-hole pairs can be produced at the interface, which separate in the built-in electric field (contact potential difference) at the semiconductor interface, generating a DC current. Research has shown that the tribovoltaic effect can occur at various interfaces, such as metal-semiconductor interface,[2] P-N semiconductors interface,[3] metal-insulator-semiconductor interface,[4] metal-insulator-metal interface,[5] and liquid-semiconductor interface.[6][7] The tribovoltaic effect may find applications in the fields of energy harvesting and smart sensing.[3]
Nomenclature
It has been suggested that the generation of tribo-current at the sliding PN junction or Schottky junction is analogous to the generation of photo-current in the photovoltaic effect, and the only difference is that the energy for exciting the electron-hole pairs is different, so it was named "tribovoltaic effect" by Wang et al.[1]

Experimental evidence
The tribovoltaic effect was observed at both macro- and nano-scale. It was found that a direct current can be generated by sliding the N-type diamond coated tip over the P-type Si samples, and the direction of the tribo-current depends on the direction of the built-in electric field at the PN and Schottky junctions.

Tribovoltaic effect at different interfaces
Metal-semiconductor interface. When a Pt-coated silicon atomic force microscopy (AFM) tip rubs on molybdenum disulfide (MoS2) surface, a DC current with a maximum density of 106 A/m2 is generated.[2] Similarly using a pure Pt tip to rub both p-type and N-type silicon samples, the current follows the contact potential.[3]
P-N semiconductors interface. When using a N-type silicon to rub with a P-type Si, a DC current from the P-type Si to the N-type silicon is produced, with the same direction as the built-in electric field at the PN junction.[8] Furthermore, when a N-type diamond-coated silicon tip is used to rub with the surfaces of N-type silicon and P-type Si, tribocurrent can be generated at the interfaces of N-type tip and P-type Si.[3]
Metal-insulator-semiconductor interface. When a conducting tip rubs with a silicon, the tribovoltaic effect can induce water molecules to form an oxide layer on the silicon surface, and the tribo-current decreases gradually with increasing the thickness of oxide layer.[4]
Metal-insulator-metal interface. The studies of DC output characteristics of Al-TiO2-Ti heterojunctions show that the open-circuit voltage increases with increasing the thickness of TiO2, while the short-circuit current first increases and then decreases. The experiments have revealed that the tribo-current is contributed by quantum tunneling, thermionic emission and trap-assisted transport.[5]
Liquid-semiconductor interface. The tribovoltaic effect can also occur at aqueous solution and solid semiconductor interface, in which the aqueous solution is considered as a liquid semiconductor.[9][10][11][12] The tribovoltaic effect at liquid-solid interface was also observed by Wang et al.[7][13]
References
- ↑ 1.0 1.1 Wang, Zhong Lin; Wang, Aurelia Chi (2019). "On the origin of contact-electrification" (in en). Materials Today 30: 34–51. doi:10.1016/j.mattod.2019.05.016. ISSN 1369-7021. https://www.sciencedirect.com/science/article/pii/S1369702119303700.
- ↑ 2.0 2.1 Liu, Jun; Goswami, Ankur; Jiang, Keren; Khan, Faheem; Kim, Seokbeom; McGee, Ryan; Li, Zhi; Hu, Zhiyu et al. (2018). "Direct-current triboelectricity generation by a sliding Schottky nanocontact on MoS2 multilayers" (in en). Nature Nanotechnology 13 (2): 112–116. doi:10.1038/s41565-017-0019-5. ISSN 1748-3387. PMID 29230042. https://www.nature.com/articles/s41565-017-0019-5.
- ↑ 3.0 3.1 3.2 3.3 Zheng, Mingli; Lin, Shiquan; Xu, Liang; Zhu, Laipan; Wang, Zhong Lin (2020). "Scanning Probing of the Tribovoltaic Effect at the Sliding Interface of Two Semiconductors" (in en). Advanced Materials 32 (21). doi:10.1002/adma.202000928. ISSN 0935-9648. PMID 32270901. Bibcode: 2020AdM....3200928Z. https://onlinelibrary.wiley.com/doi/10.1002/adma.202000928.
- ↑ 4.0 4.1 Liu, Jun; Liu, Feifei; Bao, Rima; Jiang, Keren; Khan, Faheem; Li, Zhi; Peng, Huihui; Chen, James et al. (2019). "Scaled-up Direct-Current Generation in MoS 2 Multilayer-Based Moving Heterojunctions" (in en). ACS Applied Materials & Interfaces 11 (38): 35404–35409. doi:10.1021/acsami.9b09851. ISSN 1944-8244. PMID 31476860. https://pubs.acs.org/doi/10.1021/acsami.9b09851.
- ↑ 5.0 5.1 Benner, Matthew; Yang, Ruizhe; Lin, Leqi; Liu, Maomao; Li, Huamin; Liu, Jun (2022). "Mechanism of In-Plane and Out-of-Plane Tribovoltaic Direct-Current Transport with a Metal/Oxide/Metal Dynamic Heterojunction" (in en). ACS Applied Materials & Interfaces 14 (2): 2968–2978. doi:10.1021/acsami.1c22438. ISSN 1944-8244. PMID 34990542. https://pubs.acs.org/doi/10.1021/acsami.1c22438.
- ↑ Zheng, Mingli; Lin, Shiquan; Zhu, Laipan; Tang, Zhen; Wang, Zhong Lin (2022). "Effects of Temperature on the Tribovoltaic Effect at Liquid-Solid Interfaces" (in en). Advanced Materials Interfaces 9 (3). doi:10.1002/admi.202101757. ISSN 2196-7350. https://onlinelibrary.wiley.com/doi/10.1002/admi.202101757.
- ↑ 7.0 7.1 Zheng, Mingli; Lin, Shiquan; Tang, Zhen; Feng, Yawei; Wang, Zhong Lin (2021). "Photovoltaic effect and tribovoltaic effect at liquid-semiconductor interface" (in en). Nano Energy 83. doi:10.1016/j.nanoen.2021.105810. https://linkinghub.elsevier.com/retrieve/pii/S2211285521000689.
- ↑ Xu, Ran; Zhang, Qing; Wang, Jing Yuan; Liu, Di; Wang, Jie; Wang, Zhong Lin (2019). "Direct current triboelectric cell by sliding an n-type semiconductor on a p-type semiconductor" (in en). Nano Energy 66. doi:10.1016/j.nanoen.2019.104185. https://linkinghub.elsevier.com/retrieve/pii/S2211285519308924.
- ↑ Copeland, A. Wallace.; Black, Otis D.; Garrett, A. B. (1942). "The Photovoltaic Effect.". Chemical Reviews 31 (1): 177–226. doi:10.1021/cr60098a004. ISSN 0009-2665.
- ↑ Williams, F.; Nozik, A. J. (1984). "Solid-state perspectives of the photoelectrochemistry of semiconductor–electrolyte junctions" (in en). Nature 312 (5989): 21–27. doi:10.1038/312021a0. ISSN 1476-4687. Bibcode: 1984Natur.312...21W. https://www.nature.com/articles/312021a0.
- ↑ Lewis, Nathan S. (1998). "Progress in Understanding Electron-Transfer Reactions at Semiconductor/Liquid Interfaces". The Journal of Physical Chemistry B 102 (25): 4843–4855. doi:10.1021/jp9803586. ISSN 1520-6106.
- ↑ Iqbal, Asif; Hossain, Md Sazzad; Bevan, Kirk H. (2016). "The role of relative rate constants in determining surface state phenomena at semiconductor–liquid interfaces" (in en). Physical Chemistry Chemical Physics 18 (42): 29466–29477. doi:10.1039/C6CP04952D. ISSN 1463-9084. PMID 27738683. Bibcode: 2016PCCP...1829466I. https://pubs.rsc.org/en/content/articlelanding/2016/cp/c6cp04952d.
- ↑ Lin, Shiquan; Chen, Xiangyu; Wang, Zhong Lin (2020). "The tribovoltaic effect and electron transfer at a liquid-semiconductor interface" (in en). Nano Energy 76. doi:10.1016/j.nanoen.2020.105070. ISSN 2211-2855. https://www.sciencedirect.com/science/article/pii/S2211285520306479.
