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

Concepts for the incorporation of inorganic building blocks into organic polymers on a nanoscale

Carbazole-containing polymers: synthesis, properties and applications

Summary: Carbazole-based oligomeric and polymeric materials have been studied for almost 25 years for their unique electrical, electrochemical and optical properties. Interestingly, carbazole units can be linked in two different ways leading to either poly(3,6-carbazole) or poly(2,7-carbazole) derivatives. While the former class seems to be very interesting for electrochemical and phosphorescence applications, the latter shows very promising optical properties in the visible range for light emitting diodes (LED). The major intrinsic difference between these two classes is the effective conjugation length: poly(2,7-carbazole) materials having the longer one, due to their poly(p-phenylene)-like structure. Using different synthetic strategies and substitution patterns, the physico-chemical properties of both classes can be fine-tuned, leading to high performance materials for a large number electronic applications.

Chemical structures for poly(3,6-carbazole) and poly(2,7-carbazole) and the materials used as the starting points for their respective syntheses.

Polycarbazoles: 25 Years of Progress

Emissive electron donor–acceptor (D–A) conjugates have a wide variety of applications in biophotonics, two-photon absorption materials, organic lasers, long wavelength emitters, and so forth. However, it is still a challenge to synthesize high solid-state efficiency D–A structured emitters due to the notorious aggregation-caused quenching (ACQ) effect. Though some D–A systems are reported to show aggregation-induced emission (AIE) behaviors, most are only selectively AIE-active in highly polar solvents, showing decreased solid-sate emission efficiencies compared to those in nonpolar solvents. Here we report the triphenylamine (TPA) and 2,3,3-triphenylacrylonitrile (TPAN) based D–A architectures, namely, TPA3TPAN and DTPA4TPAN. Decoration of arylamines with TPAN changes their emission behaviors from ACQ to AIE, making resulting TPA3TPAN and DTPA4TPAN nonluminescent in common solvents but highly emissive when aggregated as nanoparticles, solid powders, and thin films owing to their highly twisted configurat...

Efficient Solid Emitters with Aggregation-Induced Emission and Intramolecular Charge Transfer Characteristics: Molecular Design, Synthesis, Photophysical Behaviors, and OLED Application

Materials demonstrating a photorefractive effect are principal candidates for numerous applications, including high-density optical data storage, optical image processing, phase conjugated mirrors and lasers, dynamic holography, optical computing, pattern recognition, etc. Considerable progress has been made in the research on photorefractive polymers and composite materials in the last few years. These materials have many advantages over inorganic photorefractive crystals, including large optical nonlinearities, low dielectric constants, low cost and ease of fabrication. A large number of materials, including those exhibiting an extremely large photorefractive effect, have been developed. In addition, a number of interesting phenomena particular to polymeric photorefractive materials have been reported and corresponding mechanisms have been proposed to account for these phenomena. Possible applications of these materials have been explored with the demonstration of a volume holographic storage device based on photorefractive polymers. This paper reviews the latest developments of the young and exciting field of polymeric photorefractive materials.

Photorefractive Polymers and Composites

We report on a solution processed novel electroluminescent heterostructure device consisting of an inorganic semiconductor, CdS, and a polymer emitter, poly(p-phenylene vinylene) (PPV). This configuration provides the advantage of excellent charge transporting properties of an inorganic semiconductor and the high luminescence quantum efficiency of an organic emitter. The electroluminescence spectrum obtained from this hetrostructure device is similar to the emission spectrum of pure PPV. Even with aluminum electrode, we have achieved stable electroluminescence at very low threshold voltage (3 V) and overall quantum efficiency of about 1% in these devices. The device emitted bright electroluminescence radiation (150 cd/m2) at a driving voltage of 10 V under the forward bias condition.

Organic–inorganic heterojunction light emitting diodes based on poly(p-phenylene vinylene)/cadmium sulfide thin films

The authors report the synthesis and characterization of a new, low-T{sub g} polymer exhibiting the photorefractive effect. The photorefractive polymer contains a second-order nonlinear optical chromophore, a charge transporting group, and a long aliphatic chain covalently linked to the polymer backbone. A sensitizer (C{sub 60}) was molecularly doped into the polymer to facilitate photocharge generation. The photoconductivity, electrooptic (Pockels) effect, and photorefractive properties of the polymer are reported. 27 refs., 10 figs.

Photorefractive polymer with side-chain second-order nonlinear optical and charge-transporting groups

We present electroluminescent (EL) properties of new blue−green organic dyes. The molecular structures of these dyes are based on 2,7-divinyl-9,9-bis(tert-butyl)fluorene, a π-electron bridge, end-capped with electron donor (D) and/or electron acceptor (A) group(s) to form D−π−A, D−π−D, and A−π−A structures. The donor group is a triphenylamine, and the acceptor group is a diphenyloxadiazole. We studied EL properties of these dyes in a single-layer EL device having the following structure:  ITO/PVK:DYE/Ca/Al. We found that both the wavelength of maximum emission and the threshold of EL depend on the structure and the concentration of the dye. Among the structure reported here, the D−π−A dye shows the highest EL performance, exhibiting a brightness of 498 cd/m2 at an applied voltage of 25 V.

Ryszard Burzynski

Papers

Photorefractive Polymers and Composites

Organic–inorganic heterojunction light emitting diodes based on poly(p-phenylene vinylene)/cadmium sulfide thin films

Photorefractive polymer with side-chain second-order nonlinear optical and charge-transporting groups

Electroluminescence Properties of Systematically Derivatized Organic Chromophores Containing Electron Donor and Acceptor Groups

Second-order nonlinear optical properties of N-(4-nitrophenyl)-(s)-prolinol-doped sol-gel-processed materials