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 light-emitting diodes (OLEDs) are competitive candidates for the next generation flat-panel displays and solid state lighting sources. Efficient blue-emitting materials have been one of the most important prerequisites to kick off the commercialization of OLEDs. This tutorial review focuses on the design of blue fluorescent emitters and their applications in OLEDs. At first, some typical blue fluorescent materials as dopants are briefly introduced. Then nondoped blue emitters of hydrocarbon compounds are presented. Finally, the nondoped blue emitters endowed with hole-, electron- and bipolar-transporting abilities are comprehensively reviewed. The key issues on suppressing close-packing, achieving pure blue chromaticity, improving thermal and morphological stabilities, manipulating charge transporting abilities, simplifying device structures and the applications in panchromatic OLEDs are discussed.

Blue fluorescent emitters: design tactics and applications in organic light-emitting diodes

Introduction: Branched macromolecules or dendrimers have provided a rich seam of research in terms of both innovative chemistry and applications.1-14 For example, dendrimers have been studied for use as low-dielectric materials,15 as templates for the growth of single-wall carbon nanotubes,16 as catalysts,17-19 and in biological applications,20-23 including biosensors,24 magnetic resonance imaging,25-28 and drug delivery.29-33 However, it has only been more recently that such macromolecular structures have been explored in terms of their electronic and optoelectronic properties, which is the focus of this series of reviews. For example, charge-transporting dendrimers have become an important class of organic semiconducting material34 and significant effort has focused on light harvesting and energy transfer from a peripheral dye or chromophore to an emissive dye at the center or focus of the dendrimer.35-39 Organic semiconductors have become increasingly important as the active component in applications including organic light-emitting diodes (OLEDs),40-42 transistors,43,44 photovoltaic (PV) cells,45,46 optical amplifiers,47,48 and lasers.49-51 Traditionally, organic semiconductors have fallen into two main classes, small molecules and polymers, and these materials and their applications will be covered in detail by other authors. Small molecules are generally processed by evaporation techniques and have the advantages that the structure−property relationships are relatively simple to understand, the materials are mono(disperse), and they are deposited in a pure form. On the other hand, conjugated polymers are soluble and can be deposited from solution by processes such as spin-coating and ink-jet printing, which opens up the exciting prospect of simple, fast, large-area, low-temperature device manufacturing. An additional advantage for conjugated polymers is that solution processing is potentially less wasteful of material than evaporation for devices that require patterning. However, it is often difficult to control the polydispersity, molecular weight, backbone defects, and end groups of conjugated polymers reproducibly. Branched macromolecules, known as dendrimers, also have the advantage of being solution processable but by careful design can incorporate the control over the optoelectronic properties that is reminiscent of small molecules. In addition, the dendritic architecture provides a number of other attractive properties, including the ability to independently control the processing and optoelectronic properties; providing the processing power to enable simple chromophores to be deposited as stable amorphous films; dendrimer generation as a tool for controlling the intermolecular interactions that govern device performance; and the ability in well-defined dendrimers to have high chemical purity. In this review, we will focus on synthetic strategies that have been investigated for the preparation of optoelectronically active solution-processable dendritic materials and concentrate on two different applications, namely OLEDs and solar cells, in which they have been used. In the context of OLEDs, we limit the discussion to light emission, as branched macromolecules for charge transport will be discussed in the review by Shirota. We will also briefly comment on other recent light-emitting and -absorbing branched molecular materials that have been used in OLEDs and solar cells.

Development of Dendrimers: Macromolecules for Use in Organic Light-Emitting Diodes and Solar Cells

Blue organic light-emitting diodes (OLEDs) can play a critical role in the field of organic electroluminescence (EL). As the most important applications of OLEDs, both new generation full-color flat-panel displays and future energy-saving solid-state lighting sources require blue color EL to fulfill their functions properly. However, considerable challenges still exist in searching for highly efficient, color stable, and long-lifespan materials and devices that emit blue color, especially in the development of deep-blue emitters, which are indispensable for high-quality displays and lighting sources. Encouragingly, great progress has been made in the area of deep-blue OLEDs in recent years with continuous efforts made by scientists, who are responsible for the significant achievements in the field of OLEDs. Hence, in this review, the crucial tactics employed to obtain high performance deep-blue emitters are presented, including polymers, dendrimers, small organic molecules, delayed fluorescent systems, and phosphorescent emitters. Moreover, the future perspectives and ongoing challenges of this research frontier are also highlighted.

Recent advances of the emitters for high performance deep-blue organic light-emitting diodes

Strategies for the design and construction of non-linear, 2D and 3D conjugated macromolecules are presented in this critical review. The materials, termed here as star-shaped structures, feature a core unit which may or may not provide conjugated links between arms that radiate like spokes from a central axle. The arms of the macromolecules consist of linear oligomers or irregular conjugated chains lacking a formal repeat unit. The cores range from simple atoms to single or fused aromatic units and can provide a high level of symmetry to the overall structure. The physical properties of the star-shaped materials can be markedly different to their simple, linear conjugated analogues. These differences are highlighted and we report on anomalies in absorption/emission characteristics, electronic energy levels, thermal properties and morphology of thin films. We provide numerous examples for the application of star-shaped conjugated macromolecules in organic semiconductor devices; a comparison of their device performance with those comprising analogous linear systems provides clear evidence that the star-shaped compounds are an important class of material in organic electronics. Moreover, these structures are monodisperse, well-defined, discrete molecules with 100% synthetic reproducibility, and possess high purity and excellent solubility in common organic solvents. They feature many of the attributes of plastic materials (good film-forming properties, thermal stability, flexibility) and are therefore extremely attractive alternatives to conjugated polymers (210 references).

Star-shaped π-conjugated oligomers and their applications in organic electronics and photonics

https://pubs.acs.org/doi/pdf/10.1021/ma8027613

Monodisperse Six-Armed Triazatruxenes: Microwave-Enhanced Synthesis and Highly Efficient Pure-Deep-Blue Electroluminescence

The invention discloses a quantum dot bio-probe and a preparation method thereof. The bio-probe is a quantum dot-biological composite probe formed by the water-soluble quantum dots and the target protein ligands which are connected through coupling reaction. The invention also provides a micro-fluidic protein chip which uses the quantum dot-biological composite probe as a signal probe (detection probe). Through the adoption of the water-soluble quantum dots, the invention has better affinity with protein and other biological molecules and can obtain a quantum dot-biological composite probe with higher performances through the highly efficient coupling between the water-soluble quantum dots and the biological molecules; in addition, as the water-soluble quantum dots have no organic reagent residue, the damage to the activity of protein and other biological molecules can be minimized, and the combination properties of the biological probe can be better exerted.

Quantum point biological probe and preparation method thereof, and microcurrent control protein chip based on the same

This invention discloses manufacture of water-soluble ZnSe/ZnS core/shell quantum dots by photodegradation together with program-controlled microwave radiation method. The method comprises the steps of: mixing zinc salt or zinc oxide with water-soluble thioglycollic acid in water phase, adding sodium selenium sulfite or potassium selenium sulfite formed by reaction of sodium sulfite or potassium sulfite with selenium powders, reacting to obtain ZnSe precursor solution, placing the solution in a glass tube for microwave radiation, controlling the microwave radiation by program to obtain ZnSe quantum dots, performing photodegradation to obtain water-soluble ZnSe/Zns core/shell quantum dots with a high fluorescence quantum efficiency. The method is completely operated in water phase, thus has such advantages as easy operation and low toxicity. The quantum dots manufactured have such advantages as high fluorescence quantum efficiency, high stability and good water solubility, and can be used as fluorescent labels and indicators for biological inspection and analysis.

Preparation process of ZnSe/ZnS kernel/shell type quantum points

A method for preparing water soluble quantum of CbTe / CbS core / shell type includes mixing Cb salt with water soluble thioglycollic acid in water phase, injecting Te ?C sodium hydride to obtain CbTe forebody solution, filling said solution into glass tube specially being used in microwave radiation, carrying out program ?C controlled microwave radiation on forebody solution in said tube to prepare CbTe quantum point, obtaining water soluble CbTe / CbS core / shell quantum point with high fluorescent quantum efficiency by making light degradation on CbTe quantum point.

Wei Huang

Papers

Monodisperse Six-Armed Triazatruxenes: Microwave-Enhanced Synthesis and Highly Efficient Pure-Deep-Blue Electroluminescence

Quantum point biological probe and preparation method thereof, and microcurrent control protein chip based on the same

Preparation process of ZnSe/ZnS kernel/shell type quantum points

Preparation method of water soluble CdTe/CdS nuclear/shell type quantum point