Efficient Polymer Light‐Emitting Diode Using Air‐Stable Metal Oxides as Electrodes

Abstract

Poly(phenylenevinylene)‐based organic light‐emitting diodes (OLEDs) are fabricated using air‐stable metal oxides as electrodes, producing very efficient and bright electroluminescent devices. Efficiencies of 8 cd A−1 and luminances above 20000 cd m−2 are obtained, comparable to the values reported for classic OLED structures using reactive metals as cathodes.

Highly efficient inverted polymer light-emitting diodes using surface modifications of ZnO layer

“…However, the charge injection and transport are unbalanced in iPLEDs that use ITO or fluorine-doped tin oxide (FTO) as the cathode; n-type metal oxide, such as zinc oxide (ZnO), hafnium oxide (HfO 2 ) or zirconium oxide (ZrO 2 ), as the electron-injection/transport layer; poly(9,9 0 -dioctylfluorene-cobenzo-thiadiazole) (F8BT) or poly(phenylvinylene): super yellow as the emissive layer; molybdenum oxide (MoO 3 ) or nickel oxide (NiO) as hole injection/transport layer and gold (Au) as the anode. In fact, the hole injection in this type of device indicates an ohmic contact from the MoO 3 /Au to the highest occupied molecular orbital level of the emissive layer 25,26 , whereas the electroninjection rates are fairly low because of the considerable energy barrier difference between the conduction band (CB) of the n-type metal oxides and the lowest unoccupied molecular orbital (LUMO) of the emissive layer [9][10][11][12][13][14][15][16][17][27][28][29][30] . Recently, various strategies have been applied to promote electron injection and transport by controlling the interface between the CB of the n-type metal oxide and the LUMO of the emissive layer by using an interlayer, such as ionic liquid molecules (ILMs) 27 , conjugated polyelectrolyte 28,29 , self-assembled dipole monolayer 15 Here we show highly efficient iPLEDs by introducing a spontaneously formed ripple-shaped nanostructure of ZnO (ZnO-R) and applying an amine-based polar solvent treatment using 2-methoxyethanol (2-ME) and ethanolamine (EA) cosolvents (2-ME þ EA) to the ZnO-R.…”

Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

“…The NiO NPs exhibit a lower voltage window (∼0.7 V) electron tunneling than the parent Ni(OH) 2 Transitional metal oxides (TMOs) and hydroxides have been the subjects of extensive investigations due to their potential use in ceramics, fuel cell catalysts, rechargeable battery, and electronic components. 1 Due to their filled s -and partially filled d -orbitals, and strong ionic bond formation between metal and oxygen atoms, they show strong thermal and chemical stability 2,3 which makes them a desirable class of materials for a wide range of applications. 4 Among the TMOs, nickel oxide (NiO) has attracted a particular attention due to the fact that it is one of the relatively few TMOs with a stable band gap.…”

“…4 Among the TMOs, nickel oxide (NiO) has attracted a particular attention due to the fact that it is one of the relatively few TMOs with a stable band gap. Of recently, focus has shifted on NiO nanoparticles, due to their small size (<100 nm) and unique material and functional properties, such as a wide bandgap (∼3.88 eV), 2,3,5 high discharge capacity (∼638 mA h/g) 6 and specific capacitance (∼390 F/g), 7 high carrier density (∼7.35 × 10 18 cm -3 ), 8 and photon-to-current conversion efficiency (∼45%), 9 in addition to superb catalytic activity (42.3 gm -2 ) for CO oxidation, 10 which make them a highly desirable candidate for applications in electronics, electrochemical devices, photovoltaics, and catalysis, among others. Due to such attractive functional properties, a great deal of recent efforts have been devoted to develop application-relevant synthetic approaches, such as sol-gel embedded, 11 microemulsion precipitation, 12,13 and laser pulse deposition.…”

Electronic Structure of the Perylene–Zinc Oxide Interface: Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

“…ZnO has also been exploited as a hole-blocking / electron-selective interlayer between an indium-tin-oxide electrode and an organic electron-transport active layer in organic light-emitting diodes [4][5][6][7][8][9] as well as in organic solar cells with inverted device architectures [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] . In all these applications, charge injection at the interface between ZnO and an (organic) active layer is a critical process controlling device performance.…”