Article

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

Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom.
Chemical Reviews (Impact Factor: 46.57). 05/2007; 107(4):1097-116. DOI: 10.1021/cr050136l
Source: PubMed

ABSTRACT

The organic materials used in electronic and optoelectronic devices fall into two groups: small molecules and polymers. The former are typically deposited by vapor methods in low or high vacuum environments and have a well-defined molecular weight. The latter must be processed from solution and have a molecular weight distribution that is described by the polydispersity of the materials, giving polymers good glass-forming and mechanical properties. Dendrimers are a class of materials that in some ways fall between molecular and polymeric materials. This paper discusses the construction of dendrimers, including the use of the core-branch structure of dendrimers to control the properties of the materials on the nanometer scale as well as their use in organic light emitting diodes (LEDs) and solar cells.

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    • "Recently, much effort has been devoted to the development of new amorphous non-doped materials possessing high morphological stability [4] [5]. Dendrimer is as an alternative class of amorphous molecular electroluminescent (EL) materials [6]. Unlike small molecules and polymers, the prettiness of dendrimers is that their light emission can be finely tuned by the selection of the core, solubility can be adjusted by selecting the proper surface groups and level of intermolecular interactions can be controlled by the type and generations of the dendrons employed, that are vital part to OLEDs performance [7] [8]. "
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    ABSTRACT: A series of new N-coumarin dyes containing oligothiophenyl N-coumarins as cores and carbazole dendrons up to the third generation as substituents were synthesized and characterized. Their optical, thermal, electrochemical, and electroluminescent properties as non-doped solution-processed hole-transporting light-emitters for electroluminescent devices were investigated. It was found that by incorporating carbazole dendrons in the molecule, we were able to reduce the crystallization and maintain the high emissive ability of a planar N-coumarin fluorescent core in the solid state as well as improve the thermal stability of the material. These N-coumarins showed a bright green fluorescence and could form morphologically stable amorphous thin films with glass-transition temperatures as high as 299 °C. Simple structured solution-processed organic light-emitting diodes using these dyes as emissive layers emitted a stable green electroluminescence (λEL = 517 nm) with high luminance efficiencies (up to 9.45 cd A-1 at 6.7 mA cm-2) and high green color purity.
    Full-text · Article · Jan 2015 · Dyes and Pigments
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    • "However, simple oligothiophenes have poor solubility and hence a propensity to aggregate. Thus, in this work we have attached dendrons with suitable surface groups onto the ends of the pentathiophene to make them solution processable (Fig. 1) [14] [15]. Dendronisation of the organic chromophore can also control the level of spectral broadening in the solid-state [16], which as stated earlier is highly desirable for image sensors; particularly those designed for machine vision applications [12] [13] [16]. "
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    ABSTRACT: The photosensing ability of two blue-absorbing dendrimers is presented. Bulk heterojunction photodetectors were fabricated by spin-coating a blend solution of quinquethiophene (pentathiophene) cored conjugated dendrimers and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The photoresponse characterized under monochromatic illumination at 442 nm increases linearly with a dynamic range of ∼105. The response approaches that required for spectral selectivity for camera applications, and the external quantum efficiency of the photodetectors reached up to 22.5% at 435 nm.
    Full-text · Article · Jun 2014 · Sensors and Actuators B Chemical
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    • "The structural characterization of these highly complex structures and their interaction mechanisms are ongoing challenges. Dendrimers, spherical and mono-disperse polymers with a tree-like or generational structure, have generated a tremendous interest for many applications ranging from materials science to biomedical applications [6] [7] [8]. Dendrimers have internal cavities and functional end groups which can interact with small molecules increasing their solubilities. "
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    ABSTRACT: The interaction of poly(amidoamine)-G3 (PAMAM-G3) dendrimer with nicotinic acid (NA) was investigated by using molecular dynamics (MD) simulations. First, sample free energy profiles of NA crossing PAMAM-G3 at pH 6 and 3 were computed using the adaptive biasing force (ABF) method. We found that PAMAM-G3 provides a more appropriate environment for NA inclusion when internal tertiary amine groups are unprotonated (at pH 6). However, when internal tertiary amine groups are protonated (at pH 3), the PAMAM cavities are less hydrophobic; therefore the drug-dendrimer interactions become similar to drug-solvent interactions. Traditional MD simulations were also performed to investigate the structural stability of the PAMAM-NA complexes near the free energy minima at pH 6. We found that association of NA and PAMAM adopts a preferred binding mode around the surface of PAMAM, where hydrogen bond (HB) interactions with the amino and amide NH groups of the nearby monomers are established. These interactions are very stable whether additional van der Waals interactions between pyridine ring of NA and methylene groups of the more external monomers of PAMAM are established.
    Full-text · Article · Nov 2012 · Journal of molecular graphics & modelling
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