No abstract

Quantum dot light-emitting diodes (QLEDs) are expected to be the basis of next-generation displays and have consequently been extensively investigated with the aim of commercialization. Herein, QLED brightness, efficiency, and lifetime are significantly improved by insertion of an Al2O3 barrier layer via atomic layer deposition (ALD), which effectively suppresses the etching reaction with poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate and prevents metal ion diffusion from indium tin oxide (ITO) into the emission layer, thereby effectively reducing the effect of exciton quenching. The above-mentioned suppression of exciton quenching is verified using time-resolved photoluminescence spectroscopy/energy-dispersive X-ray spectroscopy, and a device prepared using four ALD cycles is shown to exhibit increased maximal luminance (39 410 cd/m2; two times the value achieved without the Al2O3 layer), current efficiency (47.89 cd/A; eight times the value achieved without the Al2O3 layer), and external quantum efficiency (12.89%). In addition, all Al2O3-containing QLEDs feature longer lifetimes than the QLED without Al2O3.

Area-selective atomic layer deposition (AS-ALD) is a promising technique for fine nanoscale patterning, which may overcome the drawbacks of conventional top-down approaches for the fabrication of future electronic devices. However, conventional materials and processes often employed for AS-ALD are inadequate for conformal and rapid processing. We introduce a new strategy for AS-ALD based on molecular layer deposition (MLD) that is compatible with large-scale manufacturing. Conformal thin films of "indicone" (indium alkoxide polymer) are fabricated by MLD using INCA-1 (bis(trimethylsily)amidodiethylindium) and HQ (hydroquinone). Then, the MLD indicone films are annealed by a thermal heat treatment under vacuum. The properties of the indicone thin films with different annealing temperatures were measured with multiple optical, physical, and chemical techniques. Interestingly, a nearly complete removal of indium from the film was observed upon annealing to ca. 450 °C and above. The chemical mechanism of the thermal transformation of the indicone film was investigated by density functional theory calculations. Then, the annealed indicone thin films were applied as an inhibiting layer for the subsequent ALD of ZnO, where the deposition of approximately 20 ALD cycles (equivalent to a thickness of approximately 4 nm) of ZnO was successfully inhibited. Finally, patterns of annealed MLD indicone/Si substrates were created on which the area-selective deposition of ZnO was demonstrated.

No abstract

Recently, biocompatible energy harvesting devices have received a great deal of attention for biomedical applications. Among various biomaterials, viruses are expected to be very promising biomaterials for the fabrication of functional devices due to their unique characteristics. While other natural biomaterials have limitations in mass-production, low piezoelectric properties, and surface modification, M13 bacteriophages (phages), which is one type of virus, are likely to overcome these issues with their mass-amplification, self-assembled structure, and genetic modification. Based on these advantages, many researchers have started to develop virus-based energy harvesting devices exhibiting superior properties to previous biomaterial-based devices. To enhance the power of these devices, researchers have tried to modify the surface properties of M13 phages, form biomimetic hierarchical structures, control the dipole alignments, and more. These methods for fabricating virus-based energy harvesting devices can form a powerful strategy to develop high-performance biocompatible energy devices for a wide range of practical applications in the future. In this review, we discuss all these issues in detail.