Planar refractive index patterning through microcontact photo-thermal annealing of a printable organic/inorganic hybrid material.

We demonstrate proof-of-concept refractive-index structures with large refractive-index-gradient profiles, using a micro-contact photothermal annealing (µCPA) process to pattern organic/inorganic hybrid materials comprising titanium oxide hydrate within a poly(vinyl alcohol) binder. A significant refractive index modulation of up to Δn ≈ +0.05 can be achieved with µCPA within less than a second of pulsed lamp exposure, which promises the potential for a high throughput fabrication process of photonic structures with a polymer-based system.

A novel laboratory-based hard X-ray photoelectron spectroscopy system.

Hard X-ray photoelectron spectroscopy (HAXPES) has seen continuous development since the first experiments in the 1970s. HAXPES systems are predominantly located at synchrotron sources due to low photoionization cross sections necessitating high X-ray intensities, which limits the technique's availability to a wide range of users and potential applications. Here, a new laboratory-based instrument capable of delivering monochromated X-rays with an energy of 9.25 keV and a microfocused 30 × 45 µm2 X-ray spot is introduced. The system gives an excellent energy resolution of below 500 meV coupled with good X-ray intensity. It allows stable measurements under grazing incidence conditions to maximise signal intensities. This article outlines the instrument behavior, showcases applications including bulk and multilayer measurements, and describes the overall performance of the spectrometer. This system presents an alternative to synchrotron-based experimental end stations and will help expand the number and range of HAXPES experiments performed in the future.

Low-Voltage Solution-Processed Hybrid Light-Emitting Transistors.

We report the development of low operating voltages in inorganic-organic hybrid light-emitting transistors (HLETs) based on a solution-processed ZrO x gate dielectric and a hybrid multilayer channel consisting of the heterojunction In2O3/ZnO and the organic polymer "Super Yellow" acting as n- and p-channel/emissive layers, respectively. Resulting HLETs operate at the lowest voltages reported to-date (<10 V) and combine high electron mobility (22 cm2/(V s)) with appreciable current on/off ratios (≈103) and an external quantum efficiency of 2 × 10-2% at 700 cd/m2. The charge injection, transport, and recombination mechanisms within this HLET architecture are discussed, and prospects for further performance enhancement are considered.

Modulation-Doped In2 O3 /ZnO Heterojunction Transistors Processed from Solution.

This paper reports the controlled growth of atomically sharp In2 O3 /ZnO and In2 O3 /Li-doped ZnO (In2 O3 /Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In2 O3 /ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In2 O3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In2 O3 /Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In2 O3 /Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated.

Organic Field-Effect Transistors Based on a Liquid-Crystalline Polymeric Semiconductor using SU-8 Gate Dielectrics onFlexible Substrates.

In this work, the insulating properties of poly(4-vinylphenol) (PVP) and SU-8 (MicroChem, Westborough, MA, USA) dielectrics are analyzed and compared with each other. We further investigate the performance behavior of organic field-effect transistors based on a semiconducting liquid-crystal polymer (LCP) using both dielectric materials and evaluate the results regarding the processability. Due to the lower process temperature needed for the SU-8 deposition, the realization of organic transistors on flexible substrates is demonstrated showing comparable charge carrier mobilities to devices using PVP on glass. In addition, a µ-dispensing procedure of the LCP on SU-8 is presented, improving the switching behavior of the organic transistors, and the promising stability data of the SU-8/LCP stack are verified after storing the structures for 60 days in ambient air showing negligible irreversible degradation of the organic semiconductor.