Browsing by Author "Cheng, Chiu-Ping"

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Cesium doping at C-60/rubrene heterointerfaces for improving the performance of organic light- and current-generating devices
(2015-01-07)
Cheng, Chiu-Ping
;
Lu, Meng-Han
;
Chu, Yu-Ya
;
Wei, Ching-Hsuan
;
Pi, Tun-Wen
This study examined the effect of adding cesium (Cs) at C-60/rubrene heterointerfaces by using synchrotron-radiation photoelectron spectroscopy. A C-60/rubrene heterostructure is the basis of a novel organic dual device found to facilitate efficient integration of both electroluminescent and photovoltaic functions. With Cs doping, the interfacial dipole potential was considerably enlarged, as was the separation between the lowest unoccupied molecular orbital of C-60 and the highest occupied molecular orbital of rubrene. However, the energy-level diagram indicated that a high Cs concentration prevents the formation of photoexcitons. By contrast, adding a small amount of Cs can effectively improve the efficiency of light-and current-generating devices. In particular, the deficiency of the dopants at the heterointerface may benefit the survival of photoexcitons. (C) 2015 AIP Publishing LLC.
Interfacial electronic structure of Na deposited on rubrene thin film studied by synchrotron radiation photoemission
(2015-12-01)
Wei, Ching-Hsuan
;
Cheng, Chiu-Ping
;
Lin, Hong-Cheu
;
Pi, Tun-Wen
;
材料科學與工程學系
The electronic structure of rubrene doped with various concentrations of Na was studied by synchrotronradiation photoemission. Three stages of development were found with increasing Na concentration; Na penetrating deep into the organic film, followed by development of gap states, and ended with a metallic Na film. The charge transfer from Na to rubrene resulted in a vacuum-level shift. By doping Na into rubrene, we could control the IP of the organic molecule, which is favorable for application in organic semiconductor devices. (C) 2015 Elsevier B.V. All rights reserved.
The effect of magnesium added at C-60/Rubrene heterointerfaces
(2013-12-28)
Cheng, Chiu-Ping
;
Lee, Cheng-Wei
;
Chu, Yu-Ya
;
Wei, Ching-Hsuan
;
Pi, Tun-Wen
This study examines the effect of adding magnesium (Mg) at Codrubrene heterointerfaces by using synchrotron-radiation photoetnission spectroscopy. The heterointerface was obtained by depositing C-60 on a 4-angstrom Mg/rubrene surface. The photoemission spectra showed that the added Mg preferentially interacts with and transfers negative charges to C-60. The interfacial dipole potential was significantly enlarged, as was the separation between the lowest unoccupied molecular orbital of C-60 and the highest occupied molecular orbital of rubrene. The results demonstrate that the addition of Mg should be an effective method for improving the efficiency of light- and current-generating devices. (C) 2013 AlP Publishing LLC.