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

27 Aug 2012

Volume 101, Issue 9, Articles (09xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 101, 091102 (2012); http://dx.doi.org/10.1063/1.4747168 (3 pages)

Hagay Shpaisman, Bhaskar Jyoti Krishnatreya, and David G. Grier
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds
FREE

On the triplet distribution and its effect on an improved phosphorescent organic light-emitting diode

S. W. Liu, Y. Divayana, A. P. Abiyasa, S. T. Tan, H. V. Demir, and X. W. Sun

Appl. Phys. Lett. 101, 093301 (2012); http://dx.doi.org/10.1063/1.4749278 (4 pages) | Cited 1 time

Online Publication Date: 28 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We reported phosphorescent organic light-emitting diodes with internal quantum efficiency near 100% with significantly reduced efficiency roll-off. It was found that the use of different hole transporting layer (HTL) affects the exciton distribution in the emission region significantly. Our best device reaches external quantum efficiency (EQE), current, and power efficiency of 22.8% ± 0.1%, 78.6 ± 0.2 cd/A, 85 ± 2 lm/W, respectively, with half current of 158.2 mA/cm2. This considerably outperforms the control device with N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine (NPB) (HTL) and 4,4′-N,N′-dicarbazole-biphenyl (host) with maximum EQE, current and power efficiency of 19.1% ± 0.1%, 65.6 ± 0.3 cd/A, 67 ± 2 lm/W, respectively, with half current of only 8.1 mA/cm2.
Show PACS
85.60.Jb Light-emitting devices
FREE

Polymer light-emitting devices based on a polymer/salt mixture

Bathilde Gautier and Jun Gao

Appl. Phys. Lett. 101, 093302 (2012); http://dx.doi.org/10.1063/1.4749286 (4 pages)

Online Publication Date: 28 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, we report on polymer light-emitting devices based on the mixture of a common luminescent polymer and a lithium salt. The sandwich polymer/salt devices with aluminum electrodes are poor emitters as constructed, but undergo a unique turn on process when a large voltage bias is applied at room temperature. Once activated, the devices exhibit vastly improved electroluminescence and prompt response to applied voltage. Moreover, the devices exhibit a luminance shelf life of approx. 150 h when stored at room temperature without bias. We show detailed device characteristics and discuss possible operating mechanisms for such devices. We also discuss the implication of such devices with regard to room-temperature frozen-junction devices.
Show PACS
85.60.Jb Light-emitting devices
FREE

Magnetic-field dependent differential capacitance of polymer diodes

Thaddee K. Djidjou, Tek Basel, and Andrey Rogachev

Appl. Phys. Lett. 101, 093303 (2012); http://dx.doi.org/10.1063/1.4748797 (4 pages)

Online Publication Date: 28 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using admittance spectroscopy, we found that bipolar organic diodes based on pi-conjugated polymer, 2-methoxy-5-(2′-ethylhexyloxy), MEH-PPV, have strong divergent contribution to the device differential capacitance. It is positive at low bias voltages, turns negative at intermediate biases, and becomes positive again at stronger biases. In addition, we found that at certain biases, a small magnetic field can change the capacitance from divergent negative to divergent positive. Possible physical processes responsible for this anomalous behavior of the capacitance and its relation to the phenomenon of organic magnetoresistance are discussed.
Show PACS
85.60.Jb Light-emitting devices
FREE

Time-of-flight mobility of charge carriers in position-dependent electric field between coplanar electrodes

Egon Pavlica and Gvido Bratina

Appl. Phys. Lett. 101, 093304 (2012); http://dx.doi.org/10.1063/1.4742149 (5 pages) | Cited 1 time

Online Publication Date: 29 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time-of-flight measurements of the photocurrent in thin organic semiconductor layers represent an effective way to extract charge carrier mobility. A common method to interpret the time-dependence of the photocurrent in these material systems assumes a position-independent electric field between two coplanar electrodes. In this letter, we compare time-dependence of the photocurrent, measured in the samples comprising thin layers of poly-3-hexylthiophene, with the Monte Carlo simulations. In the simulations, we have used both, a position-independent and a position-dependent electric field. We obtained a favorable agreement between the simulations and the measurements only in the case of position-dependent electric field. We demonstrate that the charge carrier mobility may be underestimated by more than one order of magnitude, if a position-independent electric field is used in the calculations of the mobility.
Show PACS
72.20.Fr Low-field transport and mobility; piezoresistance
72.40.+w Photoconduction and photovoltaic effects
73.61.Ph Polymers; organic compounds
FREE

Work function recovery of air exposed molybdenum oxide thin films

Irfan Irfan, Alexander James Turinske, Zhenan Bao, and Yongli Gao

Appl. Phys. Lett. 101, 093305 (2012); http://dx.doi.org/10.1063/1.4748978 (4 pages) | Cited 1 time

Online Publication Date: 29 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report substantial work function (WF) recovery of air exposed molybdenum oxide thin films with vacuum annealing. We observed a sharp reduction in the MoOx WF (from 6.8 eV to 5.6 eV) as well as a very thin layer of oxygen rich adsorbate on the MoOx film after an hour of air exposure. The WF of the exposed MoOx film started to gradually recover with increasing annealing temperature in vacuum, and the saturation in the WF recovery was observed at 450 °C with WF ∼6.4 eV. We further studied the interface formation between the annealed MoOx and copper phthalocyanine (CuPc). The highest occupied molecular orbital (HOMO) level of CuPc was observed to be almost pinned to the Fermi level, strongly suggesting the possibility of efficient hole injection with the vacuum annealed MoOx film.
Show PACS
73.30.+y Surface double layers, Schottky barriers, and work functions
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.40.Gh Other heat and thermomechanical treatments
73.20.At Surface states, band structure, electron density of states
71.20.Ps Other inorganic compounds
68.43.Mn Adsorption kinetics
FREE

High-efficiency organic light-emitting diodes utilizing thermally activated delayed fluorescence from triazine-based donor–acceptor hybrid molecules

Sae Youn Lee, Takuma Yasuda, Hiroko Nomura, and Chihaya Adachi

Appl. Phys. Lett. 101, 093306 (2012); http://dx.doi.org/10.1063/1.4749285 (4 pages) | Cited 2 times

Online Publication Date: 30 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have designed and synthesized a high-efficiency purely organic luminescent material, 2,4-bis{3-(9 H-carbazol-9-yl)-9 H-carbazol-9-yl}-6-phenyl-1,3,5-triazine (CC2TA) comprising the bicarbazole donor and phenyltriazine acceptor units, which is capable of emitting thermally activated delayed fluorescence. The molecular design of CC2TA allows spatial separation of HOMO and LUMO on the donor and acceptor fragments, respectively, leading to an exceptionally small singlet–triplet exchange energy (ΔEST = 0.06 eV) together with a high triplet energy. Furthermore, a high external electroluminescence quantum efficiency as high as 11% ± 1% has been achieved in the sky-blue organic light-emitting diodes employing CC2TA as an emitter.
Show PACS
85.60.Jb Light-emitting devices
FREE

High output current in vertical polymer space-charge-limited transistor induced by self-assembled monolayer

Hsiao-Wen Zan, Yuan-Hsuan Hsu, Hsin-Fei Meng, Chian-Hao Huang, Yu-Tai Tao, and Wu-Wei Tsai

Appl. Phys. Lett. 101, 093307 (2012); http://dx.doi.org/10.1063/1.4748284 (4 pages) | Cited 1 time

Online Publication Date: 30 August 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a promising solution-processed vertical transistor which exhibits high output current, high on/off current ratio, and low operation voltage. Numerous poly(3-hexylthiophene) vertical channels are embedded in vertical nanometer pores. Treating the sidewalls of pores by self-assemble monolayer with long alkyl chains enhances the pore-filling and inter-chain order of poly(3-hexylthiophene). The channel current is therefore greatly increased. A grid metal inside the porous template controls the channel potential profile to turn on and turn off the vertical transistor. Finally, the transistor delivers an output current density as 50–110 mA/cm2 at 2 V with an on/off current ratio larger than 10 000.
Show PACS
85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices)
85.30.Tv Field effect devices
FREE

Influence of dielectric-dependent interfacial widths on device performance in top-gate P(NDI2OD-T2) field-effect transistors

Hongping Yan, Torben Schuettfort, Auke J. Kronemeijer, Christopher R. McNeill, and Harald W. Ade

Appl. Phys. Lett. 101, 093308 (2012); http://dx.doi.org/10.1063/1.4748976 (4 pages) | Cited 2 times

Online Publication Date: 30 August 2012

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Resonant soft x-ray reflectivity (R-SoXR) is employed to determine the interfacial widths of the semiconductor/dielectric interface in P(NDI2OD-T2)-based top-gate organic field-effect transistors (OFETs). It is shown that the deposition of a polymer dielectric on top of a semiconducting polymer layer can affect the interface structure, even when cast from an orthogonal solvent. The observed differences in the interfacial widths for different dielectrics explain the insensitivity of OFET performance to dielectric choice for OFETs fabricated using an identical fabrication protocol. The R-SoXR results demonstrate that differences in the physical interface structure should be taken into account when considering the influence of polymer dielectrics on the performance of all solution-processed OFETs. Specifically, the importance of the choice of solvent for the deposition is highlighted.
Show PACS
85.30.Tv Field effect devices
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close