Chain-Shu Hsu is currently a professor in the Department of Applied Chemistry at National Chiao Tung University, Hsinchu, Taiwan.  His research interests include conjugated polymer, liquid crystalline polymer, polymer light emitting diodes, and nanocomposite-based light emitting devices. Here, he talks to J. Mater. Chem. about his recent hot paper.

Could you explain the significance of your article to the non-specialist?
    Devices based on small molecule-derived multilayer structures and polymeric materials have potentials application in display technology. Modern OLEDs offer substantial benefits over conventional cathode ray tubes and liquid crystal displays and can revolutionize the display industry. We have developed light emitting devices with enhanced performance by employing hybrid chromophoric amphiphile/silica-based nanocomposites formed by sol-gel co-assembly. Different kinds of light emitting devices based on these nanocomposites show improved efficiencies several times better than the corresponding pristine chromophore amphiphiles. It is the controlled and well-ordered chromophoric aggregation at the nanoscale that leads to the highly emissive states

What has motivated you to conduct this work?
          Recent developments in the organic-templated growth of materials gave rise to new types of photonic hybrid composites whose structure and function are organized hierarchically. Fluorescence quenching is the thorniest problem in the development of organic light emitting diodes with high efficiencies and is due to the larger ill-defined aggregates formed during the deposition. Here, we report the synthesis and characterization of two fluorene-based blue amphiphile emitters containing triphenylamine or anthracene side groups. Organic light emitting devices, fabricated with the nanocomposites formed from the sol-gel co-assembly of these chromophoric amphiphiles with silica precursors showed enhanced performance and have better efficiencies compared to those fabricated using pristine chromophoric amphiphiles alone. Thus we have tried to solve the problem of solid-state quenching of the organic chromophores and used them efficiently in the OLEDs. 

Where do you see this work developing in the future?
    One of the main reasons for the solid-state quenching is the ill-defined aggregates formed during the film formation. Our finding of 'controlled' chromophoric aggregation induced emission in hybrid nanocomposites may stimulate new molecular engineering endeavours in the design of luminescent organics with highly emissive aggregation states. We expect that the performance of our nanocomposite-based devices can be further enhanced by optimizing properties between organic and inorganic components and this would open real new avenues in OLED fabrication.  

Are there any particular challenges facing future research in this area?
    The fabrication of thin layers is essential for such applications and for this the molecules have to show an ordered structure within these thin films to enhance or even cause certain desired properties. The control over the size and structure at the nanoscale will be the key for the manipulation of the certain properties of the hybrid systems.