Browsing by Author "Chou, Cheng-Hsuan"

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A Metal-Oxide Interconnection Layer for Polymer Tandem Solar Cells with an Inverted Architecture
(2011-03-01)
Chou, Cheng-Hsuan
;
Kwan, Wei Lek
;
Hong, Ziruo
;
Chen, Li-Min
;
Yang, Yang
A metal-oxide-only interconnecting layer for application in inverted polymer tandem solar cells is reported. Good electrical and optical coupling of the two sub-cells is achieved by using a carefully designed MoO(3)/Al/ZnO layer, which leads to a power coversion efficiency of 5.1%. The results demonstrate that effective connection between polymer bulk heterojunctions can be realized by this facile metal-oxide interlayer.
Hybrid white-light emitting-LED based on luminescent polyfluorene polymer and quantum dots
(2007-08-01)
Chou, Cheng-Hsuan
;
Yang, Chung-He
;
Hsu, Chain-Shu
;
Chen, Teng-Ming
;
應用化學系
We report the fabrication and electroluminescence (EL) characterization of a white-emitting hybrid organic/inorganic light emitting device (LED) by integrating core-shell CdSe/ZnS quantum dots (QDs) acting as a yellow emitter and polyfluorenes as the blue emitter in a multilayered structure. The hybrid white-emitting device was fabricated by spin-coating QDs in varied concentrations onto the layer of polyfluorenes with different functional groups (i.e., sulfur-containing PF1 and PFO). Depending on the QDs concentrations and the design of the hybrid LED, our device is able to exhibit either electroluminescence from QDs or a combination of both PF and QD. The EL spectra at different driving voltages, I-V characteristics, and EL chromaticity of the LEDs based on PF1/QD and PFO/QD LEDs have been measured, investigated, and compared, respectively.
Synthesis and light emitting properties of sulfide-containing polyfluorenes and their nanocomposites with CdSe nanocrystals: A simple process to suppress keto-defect
(2007-01-05)
Yang, Chung-He
;
Bhongale, Chetan Jagdish
;
Chou, Cheng-Hsuan
;
Yang, Sheng-Hsiung
;
Lo, Chih-Nan
A new series of sulfide-containing polyfluorene homopolymers and copolymers (PFS, PF1, PF3 and PF4) comprising 9,9-di[11-(decylsulfanyl)undecyl] fluorene, 9,9-dihexylfluorene, triphenylamine or benzothiadiazole moieties were synthesized by Ni(O)-mediated Yamarnoto-coupling and palladium-catalyzed Suzuki polymerizations. Three other polyfluorenes (PF2, PF5 and PFC6) without sulfur atom in the alkyl side chains were also synthesized by a similar method for comparison purpose. These fluorene-based polymers were characterized using Ff-IR spectroscopy, elemental analysis, DSC, TGA, photoluminescence (PL) and electroluminescence (EL) spectroscopies. The synthesized polymers PFS and PF1-PF3 emit blue light at around 440-468 nm, while copolymers PF4 and PF5 emit green light at around 540 nm. In annealing experiments, these polymer films show better stability against thermal oxidation than polymer PFC6. Sulfide-containing polymers show not only good electroluminescent color stability, but their EL spectra also remain unchanged at high driving voltage. A multi-layer electroluminescent device with the configuration of ITO/PEDOT/PF1/CsF/A1 exhibited a stable sky-blue emission with color coordinates (0.21, 0.23) at 10 V, which showed a maximum brightness of 2991 cd/m(2) at 8 V (75 mA/cm(2)) and a maximum efficiency of 1.36 cd/A. Finally, by ligand exchange process, the sulfur element could form coordination bonding with quantum dots, and PLED devices using these new QDs-containing organic/inorganic hybrid materials as light-emitting layers exhibit superior or comparable EL performance compared to those without quantum dots. (c) 2006 Elsevier Ltd. All rights reserved.
ZnO nano-ridge structure and its application in inverted polymer solar cell
(2009-12-01)
Sekine, Nobuyuki
;
Chou, Cheng-Hsuan
;
Kwan, Wei Lek
;
Yang, Yang
;
應用化學系
We report a unique nano-ridge structure of zinc oxide (ZnO) and its application in high performance inverted polymer solar cells. The ZnO nano-ridge structure was formed by a sol-gel process using a ramp annealing method. As the solvent slowly evaporated due to the low heating rate, there was sufficient time for the gel particles to structurally relax and pile up, resulting in a dense and undulated film. Nano-ridges with peak as high as 120 nm and valley to valley distance of about 500 nm were formed. This film provided an effective hole blocking layer and also an increased interfacial area for electron collection. An inverted bulk heterojunction polymer solar cell was fabricated using the ZnO nano-ridge film as the electron collecting layer. The device showed a high power conversion efficiency of 4.00%, an improvement of about 25% over similar solar cells made with a planar film of ZnO nanoparticles. (C) 2009 Elsevier B.V. All rights reserved.