Electron‐injecting interlayers (ILs) which are stable in air, inject electrons efficiently, block holes, and block quenching of excitons, are very important to realize efficient inverted polymer light‐emitting diodes (IPLEDs). Two air‐stable polymer electron‐injecting interlayers (ILs), branched polyethyleneimine (PEI) and polyethyleneimine ethoxylated (PEIE) for use in IPLEDs are introduced, and the roles of the ILs in IPLEDs comparing these with a conventional Cs2CO3 IL are elucidated. These polymer ILs can reduce the electron injection barrier between ZnO and emitting layer by decreasing the work function (WF) of underlying ZnO, thereby effectively facilitating electron injection into the emitting layer. WF of ZnO covered by PEI is found to be lower than that covered by PEIE due to higher [N+]/[C] ratio of PEI. Furthermore, they can block the quenching of excitons and increase the luminous efficiency of devices. Thus, IPLEDs with PEI IL of optimum thickness (8 nm) show current efficiency (13.5 cd A–1), which is dramatically higher than that of IPLEDs with a Cs2CO3 IL (8 cd A‐1).
A highly efficient simplified organic light-emitting diode (OLED) with a molecularly controlled strategy to form near-perfect interfacial layer on top of the anode is demonstrated. A self-organized polymeric hole injection layer (HIL) is exploited increasing hole injection, electron blocking, and reducing exciton quenching near the electrode or conducting polymers; this HIL allows simplified OLED comprised a single small-molecule fluorescent layer to exhibits a high current efficiency (∼20 cd/A).
A versatile metal nanowiring platform enables the fabrication of Ag nanowires (AgNW) at a desired position and orientation in an individually controlled manner. A printed, flexible AgNW has a diameter of 695 nm, a resistivity of 5.7 μΩ cm, and good thermal stability in air. Based on an Ag nanowiring platform, an all-NW transistors array, as well as various optoelectronic applications, are successfully demonstrated.
Cesium azide (CsN3) is employed as a novel n‐dopant because of its air stability and low deposition temperature. CsN3 is easily co‐deposited with the electron transporting materials in an organic molecular beam deposition chamber so that it works well as an n‐dopant in the electron transport layer because its evaporation temperature is similar to that of common organic materials. The driving voltage of the p‐i‐n device with the CsN3‐doped n‐type layer and a MoO3‐doped p‐type layer is greatly reduced, and this device exhibits a very high power efficiency (57 lm W−1). Additionally, an n‐doping mechanism study reveals that CsN3 was decomposed into Cs and N2 during the evaporation. The charge injection mechanism was investigated using transient electroluminescence and capacitance–voltage measurements. A very highly efficient tandem organic light‐emitting diodes (OLED; 84 cd A−1) is also created using an n–p junction that is composed of the CsN3‐doped n‐type organic layer/MoO3 p‐type inorganic layer as the interconnecting unit. This work demonstrates that an air‐stable and low‐temperature‐evaporable inorganic n‐dopant can very effectively enhance the device performance in p‐i‐n and tandem OLEDs, as well as simplify the material handling for the vacuum deposition process.
Organic nanofibers (ONFs) have attracted much interest as one‐dimensional functional units in various research fields with their unique advantages. Among many fabrication methods for them, electrospinning has been in the spotlight recently because of its simplicity and versatility. In this paper, first we introduce the principle, advantages, and conditions of electrospinning and then review recent studies about electronic and photonic applications of electrospun ONFs, including organic light‐emitting diodes, organic photovoltaics, organic field‐effect transistors, lasers, and waveguides. Finally, conclusion and our suggestions for further research are given.
Organic nanowires (ONWs) are flexible, stretchable, and have good electrical properties, and therefore have great potential for use in next-generation textile and wearable electronics. Analysis of trends in ONWs supports their great potential for various stretchable and flexible electronic applications such as flexible displays and flexible photovoltaics. Numerous methods can be used to prepare ONWs, but the practical industrial application of ONWs has not been achieved because of the lack of reliable techniques for controlling and patterning of individual nanowires. Therefore, an "individually controllable" technique to fabricate ONWs is essential for practical device applications. In this paper, three types of fabrication methods of ONWs are reviewed: non-alignment methods, massive-alignment methods, and individual-alignment methods. Recent research on electronic and photonic device applications of ONWs is then reviewed. Finally, suggestions for future research are put forward.
A new technique, electro-hydrodynamic nanowire (e-NW) lithography , is demonstrated for the rapid, inexpensive, and efficient fabrication of graphene nanorib bons (GNRs) on a large scale while simultaneously controlling the location and alignment of the GNRs. A series of interesting GNR architectures, including parallel lines, grids, ladders, and stars are produced. A sub-10-nm-wide GNR is obtained to fabricate field-effect transistors that show a room-temperature on/off current ratio of ca. 70.
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