Prof. Chih-I Wu Profile

Prof. Chih-I Wu

at National Taiwan Univ

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Author

Publications (8)

Proceedings Article | 16 February 2020 Paper

The photonic properties of micro/mini LED arrays with different substrate thickness

Shu-Mei Yang, Po-Hsun Wang, Chia-Hsin Chao, Chun-Wen Chu, Yu-Sheng Chen, Feng-Pin Chang, Yen-Hsiang Fang, Chien-Chung Lin, Chih-I Wu

Proceedings Volume 11280, 112801F (2020) https://doi.org/10.1117/12.2550506

KEYWORDS: Light emitting diodes, LCDs, RGB color model, Monte Carlo methods, Photonic microstructures, Organic light emitting diodes, Optoelectronics, Optical simulations, LED displays, Light sources

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Proceedings Article | 17 September 2018 Presentation

Van der Waals epitaxy of graphene and BiI3 heterostructures for dim light detection (Conference Presentation)

Po-Han Chang, Chia-Shuo Li, Chih-I Wu

Proceedings Volume 10725, 107250O (2018) https://doi.org/10.1117/12.2321279

KEYWORDS: Heterojunctions, Graphene, Epitaxy, Photodetectors, Crystals, Semiconductor materials, Semiconductors, Visible radiation, Photoemission spectroscopy, Perovskite

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Proceedings Article | 13 September 2012 Paper

Inverted OLEDs for flexible displays

Jang-Joo Kim, Jeong-Hwan Lee, Ji Whan Kim, Sei-Yong Kim, Seung-Jun Yoo, Po-Sheng Wang, Chih-I Wu

Proceedings Volume 8476, 84760G (2012) https://doi.org/10.1117/12.977831

KEYWORDS: Organic light emitting diodes, Electrodes, Electron transport, External quantum efficiency, Interfaces, Organic electronics, Flexible displays, Oxides, Aluminum, Transistors

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SPIE Journal Paper | 27 April 2012

Enhancement of poly(3-hexylthiophene)-based solar cell with thermal-evaporated [6,6]-phenyl-C60 butyric acid methyl ester layers

Wei-Hsuan Tseng, Jeng-Yu Wang, Chung-Yen Wang, Hung Lo, Chih-I Wu, Mei-Hsin Chen

JPE, Vol. 2, Issue 1, 021009, (April 2012) https://doi.org/10.1117/12.10.1117/1.JPE.2.021009

KEYWORDS: Annealing, Solar cells, Organic photovoltaics, Photoemission spectroscopy, Molecules, Ultraviolet radiation, Aluminum, Resistance, X-rays, Polymers

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Proceedings Article | 27 August 2009 Paper

Correlation of interfacial electronic structures and transport properties in organic light emitting diodes

I-Wen Wu, Yu-Hung Chen, Chao-Kung Wang, Chih-I Wu

Proceedings Volume 7415, 74150L (2009) https://doi.org/10.1117/12.829026

KEYWORDS: Organic light emitting diodes, Interfaces, Metals, Electron transport, Aluminum, Ultraviolet radiation, Photoemission spectroscopy, Calcium, Capacitance, Organic materials

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Proceedings Article | 2 September 2008 Paper

Investigations of electron-injection mechanisms and interfacial chemical reactions of Bphen doped with rubidium carbonate in OLEDs

Mei-Hsin Chen, Dong-Seok Leem, C. Lin, G. Lee, Tun-Wen Pi, Jang-Joo Kim, Chih-I Wu

Proceedings Volume 7051, 70511C (2008) https://doi.org/10.1117/12.794142

KEYWORDS: Aluminum, Nitrogen, Rubidium, Chemical species, Organic light emitting diodes, Electron transport, Doping, Interfaces, Molecules, Chemical reactions

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Proceedings Article | 25 September 2007 Paper

Interfacial physics in organic light emitting devices

Chih-I Wu

Proceedings Volume 6766, 67660A (2007) https://doi.org/10.1117/12.730625

KEYWORDS: Cesium, Carbon monoxide, Interfaces, Metals, Doping, Photoemission spectroscopy, Physics, Ions, Laser induced fluorescence, Ultraviolet radiation

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In this paper, we will present some studies of physics at the interfaces in the organic light emitting devices. The paper can be separated into two parts. First part is the manipulation of interfacial energy structures and electron transport properties of organic semiconductors. The second part is substitution and dopant dependence of electronic structures in organic thin films I will present an investigation of the energy structures and electrical doping mechanisms of the organic semiconductor surface through current-voltage (I-V) characteristics and photoemission spectroscopies. We found that both surface energy structures and transport properties can be manipulated with mix of LiF or Cs₂CO₃. The I-V characteristics show that the current efficiency is significantly improved with Cs₂CO₃ doped either at the surface or in the bulk Alq₃. As Cs₂CO₃ doping works efficiently with Al as well as other cathode metals, the interfacial chemistry and carrier injection mechanisms of such cathode structures are compared to that of the conventional LiF thin layers. To understand the mechanisms of the improvement on electron injection, the surface energy levels of metal and organic materials were measured with ultraviolet photoemission spectroscopy (UPS) and the interfacial chemistry was studied with X-ray photoemission spectroscopy (XPS). From UPS spectra, we found that a thin layer of Cs₂CO₃, as thin as 0.5 A, at the metal and organic ETL interface can bring the Fermi level of Alq₃ from mid-gap to less than 0.2 eV below the lowest unoccupied molecular orbital (LUMO), indicating that the Alq₃ film at the interface is heavily n-type doped with Cs₂CO₃ . The smaller gap between the Fermi level and LUMO with Cs₂CO₃ reduces the electron injection barrier. Strong dipole fields are also found at the surface, which also affects the electron injection considerably. The XPS data further show that Cs ions are dissociated at the interface as soon as Cs₂CO₃ is deposited on Alq₃. The result is different from the case of LiF, in which Al metal is needed for releasing Li ions. With co-evaporation of Cs₂CO₃ with Alq₃ in the bulk as n-doping ETL, the current efficiency can be further improved, which is presumably attributed to the enhancement of the electron transport in the Alq₃ films.

Proceedings Article | 20 April 2006 Paper

Highly efficient blue phosphorescent OLEDs using large bandgap host materials

Fu-Chuan Fang, Yuan-Li Liao, Ken-Tsung Wong, Ming-Han Tsai, Hao-Wu Lin, Hai-Ching Su, Chung-chih Wu, Chih-I Wu

Proceedings Volume 6192, 61921R (2006) https://doi.org/10.1117/12.662374

KEYWORDS: Organic light emitting diodes, Quantum efficiency, Phosphorescence, Thin films, Silicon, Electroluminescence, External quantum efficiency, Excitons, Luminescence, Temperature metrology

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Showing 5 of 8 publications

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