Feng-Xia Wang

Facile microwave-assisted synthesis of uniform Sb2Se3 nanowires for high performance photodetectors

A facile and rapid microwave-assisted method was developed to synthesize uniform single-crystalline Sb2Se3 nanowires in high yields. The as-prepared Sb2Se3 nanowires were directly used for fabricating prototype photodetectors. The device displayed a remarkable response to light intensity with an on/off ratio larger than 150, short response/recovery times (0.2/1.2 s), and long-term durability. The high sensitivity and robust environmental stability of the devices demonstrate the bright prospects for Sb2Se3 nanowires in highly efficient photodetectors for practical use.

Cesium hydroxide doped tris-(8-hydroxyquinoline) aluminum as an effective electron injection layer in inverted bottom-emission organic light emitting diodes

We demonstrate highly efficient inverted bottom-emission organic light-emitting diodes (IBOLEDs) by using cesium hydroxide (CsOH) doped tris-(8-hydroxyquinoline) aluminum (Alq3) as the electron injection layer on indium tin oxide cathode, which could significantly enhance the electron injection, resulting in a large increase in luminance and efficiency. The maximum luminance, current efficiency, and power efficiency reach 21000cd∕cm2, 6.5cd∕A, and 3.5lm∕W, respectively, which are 40%–50% higher in efficiency than that of IBOLEDs with cesium carbonate (Cs2CO3) doped Alq3 as the electron injection layer, where the efficiencies are only 4.5cd∕A and 2.2lm∕W. Our results indicate that CsOH doped Alq3 should be an effective electron injection layer on a wide range of electrodes to fabricate high performance OLEDs.

A soluble nonionic surfactant as electron injection material for high-efficiency inverted bottom-emission organic light emitting diodes

A soluble nonionic surfactant, polyethylenimine 80% ethoxylated (PEIE) solution, was used as the electron injection material in inverted bottom-emission organic light emitting diodes (OLEDs). The transparent PEIE film was formed on indium-tin-oxide cathode by simple spin-coating method and it was found that the electron injection was greatly enhanced. The devices with PEIE electron injection layer had achieved significant enhancement in luminance and efficiency. The maximum luminance reached 47 000 cd/m2, and the maximum luminance efficiency and power efficiency arrived at 19.7 cd/A and 10.6 lm/W, respectively. Our results indicate that PEIE is a promising electron injection material to realize high performance OLEDs.

Preparation and ambipolar transistor characteristics of co-crystal microrods of dibenzotetrathiafulvalene and tetracyanoquinodimethane

Co-crystal microrods of dibenzotetrathiafulvalene (DBTTF) and tetracyanoquinodimethane (TCNQ) molecules with the mixed-stack structure were prepared via a facile solution process and fully characterized. The as-prepared microrods were directly used for fabricating prototype devices, which exhibited typical ambipolar charge transport characteristics. The result indicated that the co-crystal microrods of DBTTF-TCNQ were potentially useful for miniaturized devices.

Facile microwave-assisted synthesis of Klockmannite CuSe nanosheets and their exceptional electrical properties.

Klockmannite copper selenide nanosheets (CuSe NSs) are synthesized by a facile microwave-assisted method and fully characterized. The nanosheets have smooth surface and hexagonal shape. The lateral size is 200–500 nm × 400–800 nm and the thickness is 55 ± 20 nm. The current-voltage characteristics of CuSe NS films show unique Ohmic and high-conducting behaviors, comparable to the thermally-deposited gold electrode. The high electrical conductivity of CuSe NSs implies their promising applications in printed electronics and nanodevices. Moreover, the local electrical variation is observed, for the first time, within an individual CuSe NS at low bias voltages (0.1 ~ 3 V) by conductive atomic force microscopy (C-AFM). This is ascribed to the quantum size effect of NS and the presence of Schottky barrier. In addition, the influence of the molar ratio of Cu2+/SeO2, reaction temperature, and reaction time on the growth of CuSe NSs is explored. The template effect of oleylamine and the intrinsic crystal nature of CuSe NS are proposed to account for the growth of hexagonal CuSe NSs.

Tungsten oxide doped N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine as hole injection layer for high performance organic light-emitting diodes

By introducing tungsten oxide (WO3) doped N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) hole injection layer, the great improvement in device efficiency and the organic film morphology stability at high temperature were realized for organic light-emitting diodes (OLEDs). The detailed investigations on the improvement mechanism by optical, electric, and film morphology properties were presented. The experimental results clearly demonstrated that using WO3 doped NPB as the hole injection layer in OLEDs not only reduced the hole injection barrier and enhanced the transport property, leading to low operational voltage and high efficiency, but also improved organic film morphology stability, which should be related to the device stability. It could be seen that due to the utilization of WO3 doped NPB hole injection layer in NPB/tris (8-quinolinolato) aluminum (Alq3)-based device, the maximum efficiency reached 6.1 cd A−1 and 4.8 lm W−1, which were much higher than 4.5 cd A−1 and 1.1 lm W−1 of NPB/Alq3...

Facile microwave-assisted synthesis of uniform single-crystal copper nanowires with excellent electrical conductivity

A facile and rapid route for the synthesis of uniform single-crystal copper nanowires by a microwave-assisted method is demonstrated. The as-prepared copper nanowires exhibit excellent conductivity, which is comparable with electrospun copper nanofibers.

One-step fabrication of an ultralong zinc octaethylporphyrin nanowire network with high-performance photoresponse

An interconnected network of ultralong zinc octaethylporphyrin (ZnOEP) nanowires was fabricated via a solution process and directly used for constructing prototype photodetectors. The device exhibited high reproducibility and sensitivity with the largest photoswitching ratio over 104. The facile fabrication process and the superior performance made ZnOEP an ideal candidate for photodetector applications.

All solution-processed large-area patterned flexible photodetectors based on ZnOEP/PVK hybrid film

All solution-processed large-area patterned flexible photodetectors were successfully fabricated by utilizing small-molecule organic semiconductor/polymer hybrid film as an active layer and patterned printed Ag electrodes. The large-area hybrid film could be fabricated by a direct solution-process self-assembly method and had a wide absorption spectrum and improved charge transport ability, resulting in high photoresponsivity. Moreover, the device displayed fast response time, high stability and broadband spectral response. Importantly, the device exhibited high flexibility, good folding strength and electrical stability on shafts with different curvature radiuses and after bending. Even after 500 bending cycles, the device still showed good photodetector and photoswitching properties. The facile low-cost large-area fabrication process and excellent performance gives potential applications in large-scale flexible electronic devices.

Hierarchical flower-shaped organic NPB architectures with a durable water-repellent property

Hierarchical flower-shaped NPB architectures are prepared via a facile solvent evaporation method and investigated by means of SEM, TEM, FT-IR, and XRD. The results indicate that each NPB flower is composed of a number of randomly oriented nanoflakes, which are single crystals and connect with each other. Furthermore, time-dependent experiments reveal that the NPB flowers are formed via a heterogeneous nucleation, coupled with “Ostwald ripening”. The densely packed films of NPB flowers, which can withstand extreme conditions, e.g., high temperature, strong acid, and strong alkali possess a durable water-repellent property.