Advanced Materials

Cornil, J.; Beljonne, D.; Calbert, J.‐P.; Brédas, J.‐L.

doi: 10.1002/1521-4095(200107)13:14<1053::AID-ADMA1053>3.0.CO;2-7pmid: N/A

The pioneering work of Heeger, MacDiarmid, and Shirakawa, rewarded by the 2000 Nobel Prize in Chemistry, has paved the way for the development of the fields of plastic electronics and photonics. Functional organic molecular materials and conjugated oligomers or polymers now allow the low‐cost fabrication of thin films for insertion into new generations of electronic and optoelectronic devices. The performance of these devices relies on the understanding and optimization of several complementary processes (see sketch). Our goal is to discuss, from a theoretical standpoint, the electronic structure characteristics and interfacial properties that are of importance in all these areas. The concept of interface should be taken here in the microscopic sense, i.e., molecular interactions among two or several chains/molecules (of the same or of a different nature). Specifically, we will address the impact of interchain interactions within an organic layer on the transport and optical properties. These issues will therefore be more directly related to transistor and light‐emitting diode applications; however, in all instances, the aspects related to interfacial charge or energy transfer processes will dictate the ultimate performance of a material in a given device.

Finkelmann, H.; Kim, S. T.; Muñoz, A.; Palffy‐Muhoray, P.; Taheri, B.

doi: 10.1002/1521-4095(200107)13:14<1069::AID-ADMA1069>3.0.CO;2-6pmid: N/A

Tuning the wavelength of a laser emission by mechanical deformation is not as implausible as it may seem. This communication proves that it can be done with cholesteric liquid crystal elastomers. The Figure shows what happens when a beam is focussed on the sample in its relaxed (left) and its stretched form (right).

Bolognesi, A.; Botta, C.; Facchinetti, D.; Jandke, M.; Kreger, K.; Strohriegl, P.; Relini, A.; Rolandi, R.; Blumstengel, S.

doi: 10.1002/1521-4095(200107)13:14<1072::AID-ADMA1072>3.0.CO;2-9pmid: N/A

Polarized light over a large spectral region is provided by the novel procedure described in this work. The active material of these light‐emitting diodes (LEDs) is formed by two polymer layers that are oriented perpendicularly to each other. The orientation is obtained using the rubbing technique combined with thermal annealing. The Figure represents the electroluminescence (EL) emission from the two‐layer LED and its structure (see also inside front cover).

Cho, J.; Char, K.; Hong, J.‐D.; Lee, K.‐B.

doi: 10.1002/1521-4095(200107)13:14<1076::AID-ADMA1076>3.0.CO;2-Mpmid: N/A

A very short processing time for making well‐organized multilayer films can be achieved employing the novel spin self‐assembly method described in this paper. The authors elaborate on the advantages of this method versus conventional self‐assembly methods for the fabrication of multilayer polyelectrolyte films. The Figure illustrates that the spinning process (bottom) yields far better organized layers than for instance the direct dipping method (top).

Sentenac, D.; Ostrovskii, B. I.; de Jeu, W. H.

doi: 10.1002/1521-4095(200107)13:14<1079::AID-ADMA1079>3.0.CO;2-4pmid: N/A

Lamellae‐like surface ripples, as shown in the Figure, can be induced on liquid crystalline polyacrylate films. The film surface shows regular height modulations, which are attributed to coupling between local liquid crystal ordering and surface curvature energy. The properties of these films, including their use for the patterning of otherwise homogeneous surfaces, are discussed in this communication.

Kleinlogel, C.; Gauckler, L. J.

doi: 10.1002/1521-4095(200107)13:14<1081::AID-ADMA1081>3.0.CO;2-Dpmid: N/A

Sintering CeO2 to maximum density at low temperatures retaining nanometer‐sized grains can be achieved by the addition of transition metal oxides. The densification rate and obtainable density are highly increased due to the size‐dependent melting of the dopant. The transient nature of the grain boundary layer allows tailoring of the electrical properties of CeO2, making this material very attractive for many electrochemical applications.

Grosso, D.; de A. A. Soler‐Illia, G. J.; Babonneau, F.; Sanchez, C.; Albouy, P.‐A.; Brunet‐Bruneau, A.; Balkenende, A. R.

doi: 10.1002/1521-4095(200107)13:14<1085::AID-ADMA1085>3.0.CO;2-Qpmid: N/A

Structure‐directing agents that aid in the formation of ordered, mesostructured titania have been found in poly(ethylene oxide) surfactants. Thermal treatment of the films results in stiffening of the titania network, thereby providing straight channels with elliptical pore cross sections (see Figure). The preparation, characterization, and properties of these films are thoroughly discussed, as well as the possibility of extending the technique for the preparation of 3D structures.

Caruso, F.; Spasova, M.; Salgueiriño‐Maceira, V.; Liz‐Marzán, L. M.

doi: 10.1002/1521-4095(200107)13:14<1090::AID-ADMA1090>3.0.CO;2-Hpmid: N/A

Core–shell particles with tailored optical properties are obtained via manipulation of the number of Au@SiO2 nanoparticle layers deposited onto larger polymer spheres. The surface characteristics of silica, which surrounds the gold nanoparticles, are exploited to achieve a dense and uniform nanoparticle coating. The layer‐by‐layer (LbL) self‐assembly technique yet again proves to be a worthy asset for the preparation of these novel metal‐based core–shell and hollow colloids (see Figure).

Hong, E.; Jang, H.; Kim, Y.; Jeoung, S. C.; Do, Y.

doi: 10.1002/1521-4095(200107)13:14<1094::AID-ADMA1094>3.0.CO;2-Upmid: N/A

The first example of a mechanoluminescent organometallic compound, the hafnium carborane complex depicted in the Figure, has been synthesized and investigated for its luminescence properties by the authors. The compound is also electroluminescent, as verified in experiments with the hafnium carborane complex embedded in a hole‐transporting polymer.

Marsitzky, D.; Scott, J. C.; Chen, J.‐P.; Lee, V. Y.; Miller, R. D.; Setayesh, S.; Müllen, K.

doi: 10.1002/1521-4095(200107)13:14<1096::AID-ADMA1096>3.0.CO;2-Ipmid: N/A

The incorporation of anthracene monomers in fluorene polymers (see Figure) suppresses the formation of aggregates severely thereby increasing the electroluminescence quantum efficiency. The spectral properties of these new polymers, their preparation, and applications are discussed.