APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

25 Feb 2008

Volume 92, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 081101 (2008); http://dx.doi.org/10.1063/1.2883874 (3 pages)

Marcel W. Pruessner, Todd H. Stievater, and William S. Rabinovich
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds
FREE

High-efficiency and color-stable white organic light-emitting devices based on sky blue electrofluorescence and orange electrophosphorescence

Cheuk-Lam Ho, Mei-Fang Lin, Wai-Yeung Wong, Wai-Kwok Wong, and Chin H. Chen

Appl. Phys. Lett. 92, 083301 (2008); http://dx.doi.org/10.1063/1.2883935 (3 pages) | Cited 6 times

Online Publication Date: 25 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Highly efficient and color-stable two-wavelength white organic light-emitting devices (WOLEDs) combining an orange phosphor [Ir(Cz–CF3)] and a sky blue fluorescent dye BUBD-1 are fabricated where the host singlet is resonant with the fluorophore singlet state and the host triplet is resonant with the phosphor triplet level. A thin layer of 1,3,5-tris[N-(phenyl)benzimidazole]benzene between the phosphorescent and the fluorescent regions confines both singlet and triplet excitons efficiently and suppress Dexter transfer of the phosphor excitons to the nonradiative triplet state of BUBD-1. The best device reaches peak efficiencies of 19.3 cd/A and 11.1 lm/W which are superior to common two-color all-fluorescent or all-phosphor WOLEDs.
Show PACS
85.60.Jb Light-emitting devices
FREE

Very high-efficiency organic light-emitting diodes based on cyclometallated rhenium (I) complex

Xiao Li, Dongyu Zhang, Wenlian Li, Bei Chu, Liangliang Han, Jianzhuo Zhu, Zisheng Su, Defeng Bi, Dan Wang, Dongfang Yang, and Yiren Chen

Appl. Phys. Lett. 92, 083302 (2008); http://dx.doi.org/10.1063/1.2888767 (3 pages) | Cited 1 time

Online Publication Date: 26 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A phosphorescent (Ph) cyclometallated rhenium (I) (ReI) complex was synthesized by reacting 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with pentacarbonylbromorhenium in refluxing toluene solutions. The precipitates were easily sublimed to obtain a pure electrically neutral carbonyl diamine ReI complex, (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)Re(CO)3Br. The Re complex was used as an orange emitting dopant in 4,4′-N,N′-dicarbazole-biphenyl host to fabricate Ph organic light-emitting diodes (PhOLEDs). The maximum electroluminescence (EL) efficiency and luminance of 21.8 cd/A and 8315 cd/cm2 were harvested, respectively, which were the highest EL results among the PhOLEDs based on ReI complexes. The improvements of the EL performances could be ascribed to the synergistic effects of together incorporation of two reciprocally repulsive phenyl and methyl groups on the backbone of 1,10-phenanthroline molecule of the ligand.
Show PACS
85.60.Jb Light-emitting devices
FREE

Radio frequency functional capacitors made of all-organic composites of thiourea in field-responsive polymers

I. S. Bayer, A. Biswas, J. B. Szczech, E. Suhir, and M. G. Norton

Appl. Phys. Lett. 92, 083303 (2008); http://dx.doi.org/10.1063/1.2857498 (3 pages) | Cited 1 time

Online Publication Date: 26 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By incorporating an organic high dielectric constant (κ) ferroelectric crystal, thiourea, in field-responsive polymers, we fabricated radio frequency functional all-organic and solution-processable dielectric composites. Two field-responsive polymer matrices with polyvinylidene fluoride (PVDF) and π-conjugated tris(8-hydroxyquinoline)aluminum(III) inclusions were used to fabricate six model high-κ capacitor devices. Promising frequency-independent capacitance density of about 12 nF/cm2 up to 100 MHz with an estimated κ = 54 was obtained from the model systems except when thin interpenetrating PVDF crystals formed within the amorphous matrix. These structures displayed significantly lower capacitance density ( ∼ 0.7 nF/cm2). High-κ composites with low loss tangent ( ∼ 0.03) could be implemented in flexible electronics.
Show PACS
84.32.Tt Capacitors
FREE

Improvement of organic solar cell performances using a zinc oxide anode coated by an ultrathin metallic layer

J. C. Bernède, Y. Berredjem, L. Cattin, and M. Morsli

Appl. Phys. Lett. 92, 083304 (2008); http://dx.doi.org/10.1063/1.2888176 (3 pages) | Cited 12 times

Online Publication Date: 27 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors have achieved an efficient organic solar cell based on copper phthalocyanine (CuPc) layer as donor and fullerene (C60) as acceptor. The aluminum doped zinc oxide (ZnO:Al) instead of indium tin oxide (ITO) is used as the anode. An ultrathin gold film is introduced among ZnO:Al, transparent conductor oxide, and the CuPc donor layer. We show that the power conversion efficiency of this cell is enhanced by one order of magnitude compared to that achieved with a ZnO anode without ultrathin gold film. Therefore, the power conversion efficiency of this cell is comparable to that with an ITO anode.
Show PACS
84.60.Jt Photoelectric conversion
FREE

Picosecond gain switching of an organic semiconductor optical amplifier

D. Amarasinghe, A. Ruseckas, A. E. Vasdekis, G. A. Turnbull, and I. D. W. Samuel

Appl. Phys. Lett. 92, 083305 (2008); http://dx.doi.org/10.1063/1.2883975 (3 pages) | Cited 9 times

Online Publication Date: 27 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
All-optical switching of an individual pulse within a sequence of amplified pulses is demonstrated in a conjugated polymer optical amplifier. The switching was achieved using a control pulse resonant with the excited state absorption. An extinction ratio of ∼ 5.5 dB was observed, while the intensities of the remaining pulses in the sequence, spaced at 50 ps intervals, were unaffected. A pump-probe study was performed and showed full gain recovery within 2 ps.
Show PACS
42.55.Wd Fiber lasers
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
FREE

Near-infrared luminescent polymer waveguide with a 20 dB small-signal gain

Martin Djiango, Takeyuki Kobayashi, Werner J. Blau, Bin Cai, Kyoji Komatsu, and Toshikuni Kaino

Appl. Phys. Lett. 92, 083306 (2008); http://dx.doi.org/10.1063/1.2884780 (3 pages) | Cited 2 times

Online Publication Date: 28 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Near-infrared optical gain in luminescent polymeric slab asymmetric waveguides has been investigated by use of amplified spontaneous emission. Upon nanosecond photopumping, the waveguides have shown a small-signal gain coefficient of 37.2±2.1 cm−1 at 820 nm for a pump fluence of 1.57 mJ/cm2 (314 kW/cm2). The loss coefficient and transparency fluence have been found to be 7.3±1.0 cm−1 at 820 nm and 0.14 mJ/cm2 (28 kW/cm2), respectively. Furthermore, we show that a small-signal gain of 19.7±2.3 dB is achievable in a 1.2-mm-long waveguide.
Show PACS
42.79.Gn Optical waveguides and couplers
42.70.Jk Polymers and organics
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
FREE

Enhancement of normally directed light outcoupling from organic light-emitting diodes using nanoimprinted low-refractive-index layer

Soon Moon Jeong, Fumito Araoka, Yoshimi Machida, Ken Ishikawa, Hideo Takezoe, Suzushi Nishimura, and Goro Suzaki

Appl. Phys. Lett. 92, 083307 (2008); http://dx.doi.org/10.1063/1.2839897 (3 pages) | Cited 5 times

Online Publication Date: 28 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors have demonstrated increased light outcoupling from organic light-emitting diodes (OLEDs) based on nanoimprinted amorphous fluoropolymer, poly[perfluoro(4-vinyloxy-l-butene)] (PPFVB). Because PPFVB has a low refractive index and a high transmittance over wide wavelength range, the first-order Bragg diffracted light shows high directionality and decreased waveguide absorption. These characteristics provide an advantage for small- or medium-sized OLEDs, which are mainly viewed from the normal direction.
Show PACS
85.60.Jb Light-emitting devices
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.25.Bs Wave propagation, transmission and absorption
FREE

Electron and hole transport in a wide bandgap organic phosphine oxide for blue electrophosphorescence

Xiuyu Cai, Asanga B. Padmaperuma, Linda S. Sapochak, Paul A. Vecchi, and Paul E. Burrows

Appl. Phys. Lett. 92, 083308 (2008); http://dx.doi.org/10.1063/1.2885117 (3 pages) | Cited 47 times

Online Publication Date: 28 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report blue phosphorescent organic light-emitting devices (OLEDs) using an ambipolar host, N-(4-diphenylphosphoryl phenyl) carbazole (MPO12), doped with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic). The external quantum efficiency and operating voltage is 9.1(±0.1)% and 4.8 V, respectively, measured at a brightness of 800 cd/m2 with no outcoupling enhancement. By varying the layer structure of the OLEDs, we show that MPO12 is capable of transporting both electrons and holes, in contrast to previous demonstrations using diphosphine oxides, which only transported electrons. The improved hole transport results in improved device efficiency.
Show PACS
85.60.Jb Light-emitting devices
FREE

Air/vacuum dielectric organic single crystalline transistors of copper-hexadecafluorophthalocyanine ribbons

Qingxin Tang, Yanhong Tong, Hongxiang Li, and Wenping Hu

Appl. Phys. Lett. 92, 083309 (2008); http://dx.doi.org/10.1063/1.2885707 (3 pages) | Cited 1 time

Online Publication Date: 28 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Air/vacuum dielectric organic field-effect transistors (OFETs) based on submicrometer-size copper-hexadecafluorophthalocyanine single crystalline ribbon were fabricated and characterized. The n-type OFETs showed high performance with the electron mobility at ∼ 0.35 cm2 V−1 s−1 and on/off ratio at >3×105, respectively. The electrical characteristics of the devices were hardly affected by air, illumination, and continuous measurements even though the mobility was thermally activated. The high performance of the air/vacuum dielectric devices showed their potential applications in organic circuits.
Show PACS
85.30.Tv Field effect devices
FREE

Simple tandem organic photovoltaic cells for improved energy conversion efficiency

Chunfu Zhang, Shi Wun Tong, Changyun Jiang, E. T. Kang, D. S. H. Chan, and Chunxiang Zhu

Appl. Phys. Lett. 92, 083310 (2008); http://dx.doi.org/10.1063/1.2885721 (3 pages) | Cited 5 times

Online Publication Date: 28 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We proposed and demonstrated a simple tandem structure of organic photovoltaic (PV) cell for efficient light harvesting. In this device structure, a soluble fullerene derivative of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is employed simultaneously to form a bilayer heterojunction PV subcell with the underlying copper phthalocyanine (CuPc) and a bulk heterojunction PV subcell with blended poly(3-hexylthiophene-2,5-diyl) (P3HT). In comparison with the conventional tandem structure, the omission of the semitransparent intercellular connection layer reduces the complexity of the device and the light loss. The enhanced short circuit current density (JSC = 8.63 mA/cm2) and power conversion efficiency (PCE) (2.79%) of the tandem structure are nearly the sum of those of the stand-alone cells of CuPc/PCBM (JSC = 2.09 mA/cm2, PCE = 0.43%) and P3HT:PCBM (JSC = 6.87 mA/cm2, PCE = 2.50%).
Show PACS
73.50.Pz Photoconduction and photovoltaic effects
72.40.+w Photoconduction and photovoltaic effects
84.60.Jt Photoelectric conversion
FREE

Amplified spontaneous emission in quaterthiophene single crystals

Marco Polo, Andrea Camposeo, Silvia Tavazzi, Luisa Raimondo, Peter Spearman, Antonio Papagni, Roberto Cingolani, and Dario Pisignano

Appl. Phys. Lett. 92, 083311 (2008); http://dx.doi.org/10.1063/1.2884687 (3 pages) | Cited 10 times

Online Publication Date: 29 February 2008

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors demonstrate amplified spontaneous emission (ASE) from quaterthiophene single crystals and study its behavior at low temperature. The room temperature photoluminescence exhibits line narrowing (spectral width down to 10 nm) at 553 nm for excitation fluence larger than 1 mJ cm−2. At low temperature (10 K), ASE is observed from two vibronic transitions at 510 nm (0-1) and 553 nm (0–2), with line narrowing down to 5 Å, for fluences larger than 100 μJ cm−2. The stimulated emission cross section is of the order of 10−15 cm2, and the ASE is found to be strongly affected by thermally induced dynamic disorder. The emission stability under photopumping is also studied and discussed.
Show PACS
78.55.Kz Solid organic materials
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close