A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

Organic electronics are broadly anticipated to impact the development of flexible thin-film device technologies. Among these, solution-processable π-conjugated polymers and small molecules are proving particularly promising in field-effect transistors and bulk heterojunction solar cells. This Perspective analyzes some of the most exciting strategies recently suggested in the design and structural organization of π-functional materials for transistor and solar cell applications. Emphasis is placed on the interplay between molecular structure, self-assembling properties, nanoscale and mesoscale ordering, and device efficiency parameters. A critical look at the various approaches used to optimize both materials and device performance is provided to assist in the identification of new directions and further advances.

Molecular design and ordering effects in π-functional materials for transistor and solar cell applications.

WOLEDs offer new design opportunities in practical solid-state lighting and could play a significant role in reducing global energy consumption. Obtaining white light from organic LEDs is a considerable challenge. Alongside the development of new materials with improved color stability and balanced charge transport properties, major issues involve the fabrication of large-area devices and the development of low-cost manufacturing technology. This Review will describe the types of materials (small molecules and polymers) that have been used to fabricate WOLEDs. A range of device architectures are presented and appraised.

Recent advances in white organic light-emitting materials and devices (WOLEDs).

Semiconducting quantum dots, whose particle sizes are in the nanometer range, have very unusual properties. The quantum dots have band gaps that depend in a complicated fashion upon a number of factors, described in the article. Processing-structure-properties-performance relationships are reviewed for compound semiconducting quantum dots. Various methods for synthesizing these quantum dots are discussed, as well as their resulting properties. Quantum states and confinement of their excitons may shift their optical absorption and emission energies. Such effects are important for tuning their luminescence stimulated by photons (photoluminescence) or electric field (electroluminescence). In this article, decoupling of quantum effects on excitation and emission are described, along with the use of quantum dots as sensitizers in phosphors. In addition, we reviewed the multimodal applications of quantum dots, including in electroluminescence device, solar cell and biological imaging.

https://www.mdpi.com/1996-1944/3/4/2260/pdf

Quantum Dots and Their Multimodal Applications: A Review

The ability to pattern functional polymers at different length scales is important for research fields including cell biology, tissue engineering and medicinal science and the development of optics and electronics. The interest and capabilities of polymer patterning have originated from the abundance of functionalities of polymers and a wide range of applications of the patterns. This paper reviews recent advances in top-down and bottom-up patterning of polymers using photolithography, printing techniques, self-assembly of block copolymers and instability-induced patterning. Finally, challenges and future directions are discussed from the point of view of both applicability and strategies for the surface patterning of polymers.

Patterning surfaces with functional polymers

Organic light-emitting diodes (OLEDs) show promise for applications as high-quality self-emissive displays for portable devices such as cellular phones and personal organizers. Although monochrome operation is sufficient for some applications, the extension to multi-colour devices--such as RGB (red, green, blue) matrix displays--could greatly enhance their technological impact. Multi-colour OLEDs have been successfully fabricated by vacuum deposition of small electroluminescent molecules, but solution processing of larger molecules (electroluminescent polymers) would result in a cheaper and simpler manufacturing process. However, it has proved difficult to combine the solution processing approach with the high-resolution patterning techniques required to produce a pixelated display. Recent attempts have focused on the modification of standard printing techniques, such as screen printing and ink jetting, but those still have technical drawbacks. Here we report a class of electroluminescent polymers that can be patterned in a way similar to standard photoresist materials--soluble polymers with oxetane sidegroups that can be crosslinked photochemically to produce insoluble polymer networks in desired areas. The resolution of the process is sufficient to fabricate pixelated matrix displays. Consecutive deposition of polymers that are luminescent in each of the three RGB colours yielded a device with efficiencies comparable to state-of-the-art OLEDs and even slightly reduced onset voltages.

Multi-colour organic light-emitting displays by solution processing.

The synthesis and characterization of side-chain polymers functionalized with hole-transporting units and photo-cross-linkable groups, which can be used for solution-based preparation of multilayer organic light-emitting devices (OLEDs), are discussed. The concept deals with triarylamine and oxetane-functionalized styrenes, which are copolymerized by radical polymerization. Four different types of hole-transporting monomers were combined with one cross-linkable monomer in two different ratios, yielding two groups of each four polymers (P1A...P4A and P1B...P4B). The polymers were investigated by NMR spectroscopy, molecular weights were determined by GPC with light scattering, and the thermal properties were measured with differential scanning calorimetry (DSC). Optical characterization by UV−vis and fluorescence spectroscopy was performed. Electrochemical and cross-linking characteristics of the copolymers were investigated to proove this strategy's potential in application for modern multilayer polymer OL...

Synthesis and Characterization of Photo-Cross-Linkable Hole-Conducting Polymers

We demonstrate that the amplified spontaneous emission (ASE) threshold in multilayer waveguide structures suitable for the use in future organic injection lasers can be drastically reduced by inserting a crosslinked hole transport layer (HTL) between a highly conductive indium tin oxide (ITO) electrode and the polymer emission layer. While no ASE is observed when the active layer material is directly spincoated onto the ITO electrode, it can be completely restored upon insertion of a 300-nm-thick HTL. This observation is attributed to reduced attenuation of the waveguided mode enabling the ASE process and is theoretically confirmed by calculations of the mode intensity fraction propagating in the absorptive ITO electrode.

Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive transparent electrode

The I-V characteristics of organic hole-only devices based on crosslinked hole-transport layer

Salah satu kelemahan dari sensor node pada suatu wireless sensor network adalah keterbatasan sumber daya (energi), dikarenakan pada umumnya suatu sensor node hanya menggunakana sebuah baterai sebagai sumber energi yang tidak terhubung ke catu daya jala-jala. Selain itu pengguna perlu mengetahui apakah baterai yang digunakan masih memiliki cadangan energi yang cukup untuk menjalankan suatu sensor node. Solusi yang dapat digunakan yakni dengan membuat sistem monitoring kondisi baterai dari besar daya yang terdapat didalam baterai. Pada paper ini didesain dan disimulasikan sistem pengukuran daya pada sensor node, dan pembuatan sistem monitoring. Hasil perancangan menunjukan pembacaan daya yang dikonsumsi oleh sensor node saat melakukan pengiriman data dengan menggunakan modul sensor INA-219 dengan besar error ±4.42% serta faktor pengali pembacaan sensor sebesar 0.858. Jarak suatu sensor node tidak lah berpengaruh terhadap konsumsi arus yang digunakan, dengan catatan set TX power yang digunakan memiliki nilai yang sama. Serta sistem monitoring yang dapat menghasilkan human machine interface yang dapat menampilkan suatu peringatan berupa alarm apabila daya pada baterai mencapai batasan tertentu.

Paula Santi Rudati

Papers

Multi-colour organic light-emitting displays by solution processing.

Synthesis and Characterization of Photo-Cross-Linkable Hole-Conducting Polymers

Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive transparent electrode

The I-V characteristics of organic hole-only devices based on crosslinked hole-transport layer

Sistem Pengukuran Daya pada Sensor Node Wireless Sensor Network