Highly Efficient Hybrid Inorganic–Organic Light‐Emitting Diodes by using Air‐Stable Metal Oxides and a Thick Emitting Layer

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.…”

“…Inverted-structured polymer light-emitting diodes (iPLEDs) have recently been established as a the substitute for conventional PLEDs because of the good air-stability of such devices, which use high-work-function metal for the anode and air-stable metaloxide layers for the electron-and hole-injection layers [9][10][11][12][13] . However, there are certain critical obstacles impeding the realization of highly efficient iPLEDs.…”

Hybrid organic-inorganic light-emitting electrochemical cells using fluorescent polymer and ionic liquid blend as an active layer

“…[2][3][4][5][6][7] However, these HyPLEDs have intrinsic limitations in producing high device efficiency because of unbalanced charge carrier injection and transport. It has recently been reported that MoO 3 shows ohmic hole injection into materials with ionization potentials significantly deeper than that for poly͑9,9Ј-dioctylfluorene-cobenzothiadiazole͒ ͑F8BT͒.…”

Custom‐Made Morphologies of ZnO Nanostructured Films Templated by a Poly(styrene‐block‐ethylene oxide) Diblock Copolymer Obtained by a Sol–Gel Technique

“…[1][2][3] Among the many inorganic metal oxides described in the literature, ZnO in particular has been successfully established in the past two decades [4] due to its wide range of outstanding electrical and optical properties. [10][11][12][13][14][15][16][17][18][19][20] Moreover, ZnO provides a rich variety of morphologies among the inorganic semiconductors, [21] for example, nanorods, [7,22,23] nanowire arrays, [24][25][26] nanobelts, [27] tetrapods, [28] branched nanocrystals, [29] flowerlike bunches, [30] hollow spheres, hexapods, and discs. [6][7][8][9] The versatility of physical, chemical, and electro-optical properties of ZnO expedites its manifold applications in the areas of gas sensing; transducers; optically pumped lasers; photocatalysts; and energy conversion devices such as solar cells, light-emitting diodes, and many more.…”