• Rebollo, Francisco Javier Aparicio

Abstract

Organic luminescent thin films are very appealing for their implementation as active media in a large variety of photonic devices such as laser cavities, luminescent photonic crystals, optical sensors and others.Dye doped photonic polymers and nanocomposites are typically synthetized by wet routes such as sol–gel and chemical polymerization in solution which provide a good control over the aggregation state of the dye and the physicochemical characteristics of the matrix affecting the luminescent and optical properties. However, such wet methods present some limitations, when aiming at the integration into photonic and optoelectronic devices.In this context, the “Remote Plasma Assisted Vacuum Deposition” (RPAVD) synthetic procedure discussed in this communication represents a novel, and versatile method for the fabrication of photofunctional nanocomposites from non-chemically polymerizable organic or organometallic functional molecules. This approach combines the physicochemical reactions involved in plasma polymerization processes with the sublimation of functional molecules of interest for the target applications.[1-3] The deposition process is carried out in a dry, room temperature and single fabrication step. The method is scalable at wafer level and fully compatible with the use of solvent-sensitive and delicate substrates. Moreover, it is directly combinable with other vacuum and plasma processes like etching and lithography including as well the use of shadow masks for the selective coating of micrometric areas. The obtained solid thin films consist of a cross-linked plasma polymer matrix (typically insoluble in organic solvents, thermally stable at temperatures higher than the sublimation temperatures of the precursor molecules, and well adhered to the substrate) which incorporates a controllable concentration of virtually any kind of thermally stable photo-functional molecule. The thickness of the nanocomposites can be easily controlled with nanometric accuracy within a wide range (from few tens to few hundreds of nanometers) and the films present a homogeneous and very dense microstructure with a extremely smooth surface ideal for the implementation in photonic devices. The optical properties of the films (light absorption, refractive index luminescence, optical sensor response, etc.) can be optimized thanks to the accurate control the technique provides over the dye concentration. [2] We have demonstrated also the advantageous use co-polymerization processes to tailor the chemical and optical properties of the plasma polymer matrix.[3] To illustrate the possibilities and universality of the technique we present results of photonic nanocomposites based in different fluorescent compounds, such as perylene, xanthene, and flavonols dyes; as well as the integration as active media in photonic structures (ring resonators, and photonic crystals).[4,5] In the present communication especial attention will be paid to recent results about the development of luminescent photonic sensors and laser gain materials.[6,7]

Topics

• Deposition
• nanocomposite
• impedance spectroscopy
• surface
• compound
• polymer
• thin film
• laser emission spectroscopy
• etching
• lithography
• organometallic
• luminescence