In this work, we study the electrical and optical properties of organic light-emitting diodes (OLEDs) with a lithium (Li)-doped tris(8-hydroxyquinolino)-aluminum (Alq 3 ) electron transport layer (ETL). When the Li : Alq 3 doping ratio in a Li-doped Alq 3 ETL is 2 : 1, the luminous efficiency of OLEDs is 5.25 cd/A; that of an OLED without a Li-doped Alq 3 ETL is only 0.7 cd/A. X-ray photoelectron (XPS) and UV-vis absorption spectra of Li-doped Alq 3 films reveal that the Li-doped Alq 3 ETL has an improved electron conductivity. However, heavy Li doping in a Li-doped Alq 3 ETL reduces the optoelectric performance of OLEDs. Excess Li atoms or cations quench light-emitting excitons in an Alq 3 emitting layer (EML). Additionally, annealing improves the morphological stability of Li-doped Alq 3 films. An OLED, comprising a Li-doped Alq 3 ETL, requires no extrinsic thin LiF film, meeting commercial requirements, improving reproducibility and ensuring uniformality in a large area.

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The effects of postfabrication thermal annealing on the performance and stability of organic light-emitting diodes ͑OLEDs͒ were systematically investigated in standard indium tin oxide/4,4Ј,4Љ-tris͑3-methylphenylphenylamino͒triphenylamine/N, NЈ-diphenyl-N, NЈ-bis͑l-naphthyl-phenyl͒-͑1,1Ј-biphenyl͒-4,4Ј-diamine Alq 3 devices. Electrical and optical performance, surface morphology of organic thin films, and operation stability of the devices with different thermal treatments were measured and monitored. It was found that devices that were thermally annealed at 70°C exhibited the best performance. Moreover, those devices had the best thin-film morphology and the lowest degradation of electroluminescent performance. The operating stability of the heat-treated device was improved by a factor of over 1.7 times than annealed devices and a half-brightness lifetime of over 7200 h was obtained. The 70°C thermally annealed devices have modified and enhanced the bonding at the interfaces of the organic layer, resulting in decreased turn-on voltage, less leakage current, higher luminescence, and longer lifetime.

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We report on tunneling spectroscopy measurements using a scanning tunneling microscope (STM) on the spin triplet superconductor Sr 2 RuO 4 . A fully open gap, close to the Bardeen-Cooper-Schrieffer (BCS) value, is found, which disappears at the bulk T c = 1.5 K. The results are discussed in the framework of recent multigap scenarios for an unconventional spin triplet superconductor. Superconductivity in the ruthenate compound Sr 2 RuO 4 has puzzled many scientists in the past decade [1]. A number of experiments, reviewed in [2], show that this superconductor could become the metallic analogue to superfluid 3 He. Strong indications that this material may be indeed an odd parity superconductor [3] have been repeatedly found since the first report for the absence of a change in the Knight shift in NMR experiments [4]. Sr 2 RuO 4 crystallizes in the layered perovskite structure common to cuprates [1]; it has a critical temperature T c of 1.5 K, and is a good metallic system with a relatively simple Fermi surface consisting of three nearly cylindrical sheets, all of them derived from the Ru 4d orbitals, and mass renormalization factors between 3 and 5.5 [5]. Identifying the structure of the superconducting gap over the Fermi surface is of prime importance for understanding spin triplet superconductivity in this material. In high quality samples, the electronic contribution to the specific heat at the lowest temperatures extrapolates very close to zero [6]. The curves do not show activated behavior, which has been taken as evidence for the presence of nodes somewhere on the Fermi surface [2]. Other