Enhancing Efficiency of Organic Light-Emitting Diodes Using a Carbon-Nanotube-Doped Hole Injection Layer

Abstract

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

Ultraviolet-ozone-treated PEDOT:PSS as anode buffer layer for organic solar cells

“…However, phase separation of PEDOT and PSS is generally found with the insulating PSS grains atop the as-prepared PEDOT: PSS film cast from aqueous PEDOT:PSS solution, which leads to a low conductivity below 1 S/cm and an improper contact condition between PEDOT:PSS and the following organic layer [ 9 ]. Many strategies have been proposed to address such an issue, such as adding sorbitol [ 10 - 12 ], glycerol [ 11 ], N-methylpyrrolidone [ 12 ], isopropanol [ 12 ], dimethyl sulfoxide [ 13 , 14 ], N,N-dimethyl formamide [ 13 ], tetrahydrofuran [ 13 ], ethylene glycol [ 14 ], 2-nitroethanol [ 14 ], 1-methyl-2-pyrrolidinone [ 14 ], mannitol [ 15 ], sodium p-toluenesulfonate [ 16 ], carbon nanotube [ 17 ], and pentacene [ 18 ] into PEDOT:PSS aqueous solution and treating the as-prepared PEDOT:PSS film with solvents [ 14 , 19 ], thermal annealing [ 20 ], oxygen plasma [ 21 ], Ar ion sputtering [ 22 ], zwitterions [ 23 ], salt solution [ 24 ], and H 2 SO 4 [ 25 ]. However, these methods make the device construction process more complex and require careful control of the technologies to avoid the deterioration of the PEDOT:PSS film properties.…”

Effects of the Introduced Single-Wall Carbon Nanotubes on the Performance of Blue Phosphorescence Organic Light-Emitting Diodes

“…As SWCNTs are doped into PEDOT:PSS, the interactions between nanotubes and PEDOT:PSS can produce structural or chemical defects in the conjugated polymer, and the defects can act as hole traps, resulting in retarded transporting ability of the holes in PEDOT:PSS. 13 Thus, the holes and the exciton recombination decrease, which leads to the decrease in current density and luminance of device D2. As SWCNTs are doped into EML, the presence of SWCNTs near the PEDOT:PSS/nanocomposite interface induces easy hole injection.…”

All-solution-processed inverted organic solar cell with a stacked hole-transporting layer

“…It has many advantages such as high transparency, a high work function, smooth morphology, and good conductivity. [16][17][18][19] Devices based on copper phthalocyanine (CuPc) have been studied extensively because of the low cost, chemical and physical stability, and outstanding photophysical and electrochemical properties of CuPc. 20) The CuPc highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels are approximately 5.0/3.6 eV, and excitons can be dissociated at the corresponding donor/acceptor interface.…”