TY - JOUR
T1 - Enhanced output performance of ZnO thin film triboelectric nanogenerators by leveraging surface limited ga doping and insulting bulk
AU - Lee, Ping Che
AU - Ou, Yi Chen
AU - Wang, Ruey Chi
AU - Liu, Chuan Pu
N1 - Funding Information:
The research was supported by Hierarchical Green-Energy Materials (Hi-GEM) Research Center , NCKU, R.O.C. technically as well as Ministry of Education and Ministry of Science and Technology , R.O.C. financially, (Grant NO. MOST 107-2221-E-006–021-MY3 , MOST 107-2221-E-006-020-MY3 , MOST 109-2622-8-006-005 , MOST109-2623-8-006-005 , MOST 110-2634-F-006-017 ). The authors also gratefully acknowledge the use of HR-SEM (Hitachi SU8000 by Ms H.L. Sze) and Ultrahigh resolution TEM (JEOL JEM-2100 F CS STEM by Ms S.W. Tseng) in the Instrument Center of National Cheng Kung University in Taiwan.
Funding Information:
The research was supported by Hierarchical Green-Energy Materials (Hi-GEM) Research Center, NCKU, R.O.C. technically as well as Ministry of Education and Ministry of Science and Technology, R.O.C. financially, (Grant NO. MOST 107-2221-E-006–021-MY3, MOST 107-2221-E-006-020-MY3, MOST 109-2622-8-006-005, MOST109-2623-8-006-005, MOST 110-2634-F-006-017). The authors also gratefully acknowledge the use of HR-SEM (Hitachi SU8000 by Ms H.L. Sze) and Ultrahigh resolution TEM (JEOL JEM-2100 F CS STEM by Ms S.W. Tseng) in the Instrument Center of National Cheng Kung University in Taiwan.
Publisher Copyright:
© 2021 The Authors
PY - 2021/11
Y1 - 2021/11
N2 - Although triboelectric nanogenerator (TENG) has been developed as a new green energy source, the dominant charge transfer mechanism regarding surface chemistry has not been fully uncovered yet, especially in semiconductor materials. Semiconductor materials are technically important not only capable of tuning total carrier concentrations available for charge transfer in TENG, but corresponding optoelectronic properties for applications into tribo-tronics. However, doping renders one serious drawback as tribo-charges tend to leak and cannot be held in place for energy output. In order to prevent carriers from leaking while maintain the characteristics of tunable carrier concentrations in semiconductors, a two-layer structure of Ga-doped ZnO/undoped-ZnO is proposed by a two-step growth methodology. A ZnO thin film was first grown by magnetron sputter followed by Ga doping restricted to a shallow surface region by thermal diffusion treatment in the second step. The results support that surface work function difference between two materials in electrification under the well preservation of tribo-charges retention governs the charge transfer capability responsible for output performance of TENGs, where the output voltage and current of the ZnO film doped with 0.93 at% Ga can be drastically enhanced by 16 and 13 times, respectively. However, β-Ga2O3 forms on the surface when Ga concentration is higher than 0.93 at%. Nevertheless, the even larger work function of β-Ga2O3 than Ga-doped ZnO does not lead to larger output performance, implying that work function difference is not the prime factor but carrier concentration in the conduction band needs to be considered for the performance of TENGs. This work demonstrated a viable method to modify the work function of ZnO only confined to the surface through doping without disturbing the bulk, optimizing the device structure for TENGs based on semiconductor.
AB - Although triboelectric nanogenerator (TENG) has been developed as a new green energy source, the dominant charge transfer mechanism regarding surface chemistry has not been fully uncovered yet, especially in semiconductor materials. Semiconductor materials are technically important not only capable of tuning total carrier concentrations available for charge transfer in TENG, but corresponding optoelectronic properties for applications into tribo-tronics. However, doping renders one serious drawback as tribo-charges tend to leak and cannot be held in place for energy output. In order to prevent carriers from leaking while maintain the characteristics of tunable carrier concentrations in semiconductors, a two-layer structure of Ga-doped ZnO/undoped-ZnO is proposed by a two-step growth methodology. A ZnO thin film was first grown by magnetron sputter followed by Ga doping restricted to a shallow surface region by thermal diffusion treatment in the second step. The results support that surface work function difference between two materials in electrification under the well preservation of tribo-charges retention governs the charge transfer capability responsible for output performance of TENGs, where the output voltage and current of the ZnO film doped with 0.93 at% Ga can be drastically enhanced by 16 and 13 times, respectively. However, β-Ga2O3 forms on the surface when Ga concentration is higher than 0.93 at%. Nevertheless, the even larger work function of β-Ga2O3 than Ga-doped ZnO does not lead to larger output performance, implying that work function difference is not the prime factor but carrier concentration in the conduction band needs to be considered for the performance of TENGs. This work demonstrated a viable method to modify the work function of ZnO only confined to the surface through doping without disturbing the bulk, optimizing the device structure for TENGs based on semiconductor.
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U2 - 10.1016/j.nanoen.2021.106394
DO - 10.1016/j.nanoen.2021.106394
M3 - Article
AN - SCOPUS:85113220089
SN - 2211-2855
VL - 89
JO - Nano Energy
JF - Nano Energy
M1 - 106394
ER -