Browsing by Author "Suen, Shich-Chang"

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Growth enhancement and field emission characteristics of one-dimensional 3,4,9,10-perylenetetracarboxylic dianhydride nanostructures on pillared titanium substrate
(2007-10-01)
Suen, Shich-Chang
;
Whang, Wha-Tzong
;
Hou, Fu-Ju
;
Dai, Bau-Tong
;
材料科學與工程學系
We have utilized the pi-pi interactions between 3,4,9, 1 0-perylenetetracarboxylic dianhydride (PTCDA) molecules and temperature-induced morphology changes to synthesize one-dimensional (ID) nanostructures of PTCDA on a heated (ca. 100 degrees C) titanium substrate through vacuum sublimation. Because of the pillared Ti structures and the presence of reactive Ti-Cl sites, the titanium substrate played a crucial role in assisting the PTCDA molecules to form ID nanostructures. The average diameter of the nanofibers deposited on the Ti-CVD substrate, a Ti substrate formed by chemical vapor deposition (CVD), at 100 degrees C was ca. 84 run, with lengths ranging from 100 nm to 3 mu m. When the PTCDA nanofibers were biased under vacuum, the emission current remained stable. The turn-on electric field for producing a current density of 10 mu A/cm(2) was 8 V/mu m. The maximum emission current density was 1.3 mA/cm(2), measured at 1100 V (E = 11 V/mu m). From the slope of the straight line obtained after plotting ln(J/E-2) versus 1/E, we calculated the field enhancement factor beta to be ca. 989. These results demonstrate the PTCDA nanofibers have great potential for applicability in organic electron-emitting devices. (C) 2007 Elsevier B.V. All rights reserved.
Low-temperature self-assembly of copper phthalocyanine nanofibers
(2006-10-01)
Suen, Shich-Chang
;
Whang, Wha-Tzong
;
Hou, Fu-Ju
;
Dai, Bau-Tong
;
材料科學與工程學系
This paper describes a method for producing ID organic nanofibers by exploiting intermolecular dispersive forces during the self-assembly of CuPc molecules. The average length of these CuPc nanofibers deposited at 100 degrees C, a temperature much lower than that required for the synthesis of carbon nanotubes, was ca. 500 nm, with diameters in the range 1550 nm. XRD analysis of these nanofibers revealed that they possessed an alpha phase structure. HRTEM images indicated that the CuPc nanofibers formed through layered stacking of CuPc molecules. These CuPc nanofibers exhibit field emission characteristics (with a turn-on field of 13.6 V/mu m) and follow Fowler-Nordheim behavior in a manner similar to that of carbon nanotubes. The stable emission current and relative simplicity of their synthesis suggest a broad range of applications for CuPc nanofibers in nanoscience and nanotechnology. (C) 2006 Elsevier B.V. All rights reserved.
Morphological control of CuPc and its application in organic solar cells
(2008-10-15)
Hsiao, Yu-Sheng
;
Whang, Wha-Tzong
;
Suen, Shich-Chang
;
Shiu, Jau-Ye
;
Chen, Chih-Ping
We have prepared organic photovoltaic (OPV) cells possessing an ideal bulk heterojunction (BHJ) structure using the self-assembly of copper phthalocyanine (CuPc) as the donor material and fullerene (C(60)) as the acceptor. The variable self-assembly behavior of CuPc on a diverse range of substrates (surface energies) allowed us to control the morphology of the interface and the degree of carrier transportation within the active layer. We observed rod-like CuPc structures on indium-tin oxide (ITO), poly(3,4-ethylenedioxythiophene)poly(4-styrenesulfonate) (PEDOT: PSS) and Au substrates. Accordingly, the interfaces and continuing transport path between CuPc and fullerene domains could be greatly improved due to the ideal BHJ structure. In this paper, we discuss the mechanisms of producing CuPc rod-like films on ITO, PEDOT: PSS and Au. The OPV cell performance was greatly enhanced when a mixture of horizontal and vertical CuPc rods was present on the PEDOT: PSS surfaces, i.e. the power conversion efficiency was 50 times greater than that of the corresponding device featuring a planar CuPc structure.