APL: Organic Electronics and Photonics

Sign change in the organic magnetoresistance of tris(8-hydroxyquinolinato)aluminum upon annealing

Hoju Kang, Ik-Jae Lee, and Choon Sup Yoon
We report the sign change in the magnetoresistance of a tris(8-hydroxyquinolinato)aluminum film with the morphological change from amorphous to crystalline state upon annealing. The negative component of the magnetoresistance followed power law behavior, whereas the positive one showed non-Lorentzia ... [Appl. Phys. Lett. 100, 073302 (2012)] published Mon Feb 13, 2012.

Organic photovoltaic cells with nano-fabric heterojunction structure

June Hyoung Park, Austin R. Carter, Lynetta M. Mier, Chi-Yueh Kao, Sharlene A. M. Lewis et al.
Organic photovoltaic cells containing electron-transporting organic nanofibers in the form of nanofabrics are investigated. Nano-fabric heterojunctions of poly(3-hexylthiophene) and electron-transporting nanofibers significantly improve short-circuit current density in organic photovoltaic cells. Th ... [Appl. Phys. Lett. 100, 073301 (2012)] published Mon Feb 13, 2012.

Electron mobility determination of efficient phosphorescent iridium complexes with tetraphenylimidodiphosphinate ligand via transient electroluminescence method

Ming-Yu Teng, Song Zhang, Sheng-Wei Jiang, Xu Yang, Chen Lin et al.
The electron mobility of Alq and iridium complexes was determined via transient electroluminescence (EL) method based on ITO (indium tin oxide)/di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane/complex/LiF/Al with short and rectangular driving voltage pulses. Apparent values of the electron mobility ([mu ... [Appl. Phys. Lett. 100, 073303 (2012)] published Mon Feb 13, 2012.

Investigation of the device instability feature caused by electron trapping in pentacene field effect transistors

Chang Bum Park
The phenomenon of device instability governed by electron trapping was investigated in pentacene field-effect transistors. We found that the threshold voltage shift (DeltaV) increases significantly when the device is exposed to photo-irradiation with the depletion gate bias. This effect reveals that ... [Appl. Phys. Lett. 100, 063306 (2012)] published Fri Feb 10, 2012.

Bloch surface waves-controlled fluorescence emission: Coupling into nanometer-sized polymeric waveguides

Mirko Ballarini, Francesca Frascella, Emanuele Enrico, Pietro Mandracci, Natascia De Leo et al.
The lateral confinement of Bloch surface waves on a patterned multilayer is investigated by means of leakage radiation microscopy (LRM). Arrays of nanometric polymeric waveguides are fabricated on a proper silicon-nitride/silicon-oxide multilayer grown on a standard glass coverslip. By exploiting th ... [Appl. Phys. Lett. 100, 063305 (2012)] published Fri Feb 10, 2012.

Fullerene acceptor for improving open-circuit voltage in inverted organic photovoltaic devices without accompanying decrease in short-circuit current density

Yutaka Matsuo, Junichi Hatano, Takayuki Kuwabara, and Kohshin Takahashi
A poly(3-hexylthiophene) (P3HT)-based inverted organic photovoltaic (OPV) device with a fullerene electron acceptor, (dimethyl(o-anisyl)silylmethyl)(dimethylphenylsilylmethyl)[60]fullerene (SIMEF2), exhibited 2.9% power conversion efficiency (PCE; J = 7.9 mA/cm, V = 0.66 V, and FF = 0.56) in the dev ... [Appl. Phys. Lett. 100, 063303 (2012)] published Wed Feb 8, 2012.

Efficient hybrid white polymer light-emitting devices with electroluminescence covered the entire visible range and reduced efficiency roll-off

Sujun Hu, Minrong Zhu, Qinghua Zou, Hongbin Wu, Chuluo Yang et al.
We report efficient hybrid white polymer light emitting devices (WPLEDs) fabricated via simple solution-proceeded process from a newly synthesized wide band-gap fluorene-co-dibenzothiophene-S,S-dioxide copolymer, which dually function as fluorescent blue emitter and host material for electrophosphor ... [Appl. Phys. Lett. 100, 063304 (2012)] published Wed Feb 8, 2012.

Four-mode plasmonic structure based on a prism-grating anticrossing bandgap

R. Chulia-Jordan and D. Santamaria-Perez
We have developed a plasmonic structure based on an anticrossing bandgap prism-grating coupling technique. We observe that up to four surface plasmons can be excited simultaneously in this plasmonic structure. Initial experiments confirm that such a plasmonic structure can improve sensor performance ... [Appl. Phys. Lett. 100, 063301 (2012)] published Tue Feb 7, 2012.

Mixed self-assembled monolayer of molecules with dipolar and acceptor characterInfluence on hysteresis and threshold voltage in organic thin-film transistors

Abdesselam Jedaa, Michael Salinas, Christof M. Jager, Timothy Clark, Alexander Ebel et al.
In this report, we investigate the impact of the molecular dipole moment and redox active head groups (C) in pure and mixed self-assembled monolayers (SAMs), which serve as an ultra-thin hybrid dielectric layer in low-voltage operating organic thin-film transistors. We show that the dipole of the SA ... [Appl. Phys. Lett. 100, 063302 (2012)] published Tue Feb 7, 2012.

Cross-linking of a poly(3,4-ethylene dioxythiophene):(polystyrene sulfonic acid) hole injection layer with a bis-azide salt and the effect of atmospheric processing conditions on device properties

Oliver Fenwick, Kate Oliver, and Franco Cacialli
We investigate the role of atmospheric conditions during processing when cross-linking a poly(3,4-ethylene dioxythiophene):(polystyrene sulfonic acid) hole injection layer with a bis-azide salt. In particular, we investigate nitrogen atmosphere and air, since there is a competing reaction of the cro ... [Appl. Phys. Lett. 100, 053309 (2012)] published Fri Feb 3, 2012.

Cumulative effects of electrode and dielectric surface modifications on pentacene-based transistors

Melanie Devynck, Pascal Tardy, Guillaume Wantz, Yohann Nicolas, Luc Vellutini et al.
Surface modifications of the dielectric and the metal of pentacene-based field effect transistors using self-assembled monolayer (SAM) were studied. First, a low interfacial trap density and pentacene 2D-growth were favored by the nonpolar and low surface energy of octadecyltrichlorosilane-based SAM ... [Appl. Phys. Lett. 100, 053308 (2012)] published Fri Feb 3, 2012.

Optimal parameters for morphology of bulk heterojunction solar cells from simulations

Junwei Xue, Tingjun Hou, and Youyong Li
We combine atomistic simulation with mesoscale simulation to predict the morphology of bulk heterojunction (BHJ) solar cells. We show that good morphology is formed for weight fraction of PCBM in the region of 0.410.62 for poly(3-hexylthiophene)/[6,6]-phenyl-C butyric acid methyl ester BHJ solar cel ... [Appl. Phys. Lett. 100, 053307 (2012)] published Thu Feb 2, 2012.

Understanding metal doping for organic electron transport layers

Alexander Mityashin, David Cheyns, Barry P. Rand, and Paul Heremans
This work concerns the physical mechanisms of metal n-doping in charge transport layers for optoelectronic devices, for which the doping level is constrained by transparency requirements so as to avoid parasitic absorption. Comparing various metal dopants, we claim that enhanced conductivity at low ... [Appl. Phys. Lett. 100, 053305 (2012)] published Wed Feb 1, 2012.

Electrical phase transition of poly(4,4[prime]-aminotriphenylene hexafluoroisopropylidenediphthalimide) by photogenerated charged carrier injection

Kyoung-Jae Lee, Dong Min Kim, Kyuwook Ihm, Moonhor Ree, Tai-Hee Kang et al.
We show a set-up of poly(4,4[prime]-aminotriphenylene hexafluoroisopropylidenediphthalimide) (6F-TPA PI)/Al sample in which holes are injected by photoelectron emission process instead of direct charge carrier injection via metal electrode. In this process, an irreversible electrical phase transitio ... [Appl. Phys. Lett. 100, 053306 (2012)] published Wed Feb 1, 2012.

Enhanced efficiency of organic light-emitting devices with metallic electrodes by integrating periodically corrugated structure

Yan-Gang Bi, Jing Feng, Yun-Fei Li, Yu Jin, Yue-Feng Liu et al.
Photons trapped in form of surface-plasmon polariton (SPP) modes associated with the metallic electrode/organic interface results in a large energy loss in organic light-emitting devices (OLEDs). We demonstrate efficient outcoupling of SPP modes from one of two metal electrodes by integrating a peri ... [Appl. Phys. Lett. 100, 053304 (2012)] published Tue Jan 31, 2012.

Unipolar depletion-load organic circuits on flexible substrate by self-organized polymer blending with 6, 13-bis(triisopropylsilylethynyl)pentacene using ink-jet printing

Sung Hoon Kim, Hye Rim Hwang, Ho Joong Kwon, and Jin Jang
We report the threshold voltage control and its application to electronic circuits of ink-jet printed organic thin-film transistors (OTFTs) with self-organized process using 6, 13-bis(triisopropylsilyl-ethynyl)pentacene (TIPS-pentacene) and insulating polymer on plastic substrate. The threshold volt ... [Appl. Phys. Lett. 100, 053302 (2012)] published Tue Jan 31, 2012.

Spin transport in poly(metalarenylsilane)

Yukihito Matsuura
We focused on the spin transport properties of polymers containing ferrocene and the related transition-metal-benzene sandwich compound (metal = Cr and V) with a silicon bridge such as poly(ferrocenylsilane) and poly(metalarenylsilane). As a model system, a sulfur-substituted oligomer was put on gol ... [Appl. Phys. Lett. 100, 053303 (2012)] published Tue Jan 31, 2012.

Short circuit current improvement in planar heterojunction organic solar cells by multijunction charge transfer

J. C. Wang, S. Q. Shi, C. W. Leung, S. P. Lau, K. Y. Wong et al.
A multijunction structure was applied on an organic photovoltaic (OPV) device for broadening the absorption spectrum and enhancing the power conversion efficiency through charge transfer process. By inserting the tris[4-(2-thienyl)]amine (TTPA) into a boron subphthalocyanine chloride (SubPc)/C OPV d ... [Appl. Phys. Lett. 100, 053301 (2012)] published Mon Jan 30, 2012.

Enhanced carrier injection in pentacene thin-film transistors by inserting a MoO-doped pentacene layer

Zhaokui Wang, Mir Waqas Alam, Yanhui Lou, Shigeki Naka, and Hiroyuki Okada
We report on the enhanced carrier injection in pentacene thin-film transistors with a thin MoO-doped pentacene layer between pentacene semiconductor and the source-drain electrodes. Device performance including drain current, field effect mobility, and threshed voltage are improved by employing a Mo ... [Appl. Phys. Lett. 100, 043302 (2012)] published Fri Jan 27, 2012.

Micro-imprinted prism substrate for self-aligned short channel organic transistors on a flexible substrate

Jin Jeon, Benjamin C.-K. Tee, Boris Murmann, and Zhenan Bao
Using a simple micro-imprinting process on flexible substrates, we demonstrate fabrication of self-aligned short channel organic thin film transistors (OTFTs) with significantly reduced parasitic capacitance. The surface topology resulting from the imprinted prism-like structures enables accurate al ... [Appl. Phys. Lett. 100, 043301 (2012)] published Mon Jan 23, 2012.

Morphological control of hybrid polymer-quantum dot solar cells with electron acceptor ligands

Mathieu Boivin, Sebastien Lamarre, Jonathan Tessier, Marie-Eve Lecavalier, Ahmed Najari et al.
We integrate the electro-attractive conjugated molecule tetrafluoro-tetracyano-quinodimethane (FTCNQ) in the active layer of polymer-CdSe colloidal quantum dot (cQD) solar cells. The addition of this molecule enhances cQD dispersion inside the polymer. In tuning its concentration, we can optimize th ... [Appl. Phys. Lett. 100, 033302 (2012)] published Fri Jan 20, 2012.