Flexographic printing of ultra-thin semiconductor polymer layers

Methods of fabricating and controlling organic light emitting diode (OLED) or photovoltaic layers effectively are paramount for achieving a functional and durable device. The deposited film needs to be uniform and homogeneous to avoid non-uniform luminescence in the OLED. Although methods of depositing the ultra-thin sub 100 nm layers within OLED are effective, they are relatively slow and expensive. This paper therefore demonstrates flexography as an alternative method for depositing the semiconductor layer for OLED onto glass substrate. In this case a proprietary semiconducting polyflourine dispersed in xylene was used. This material functions as the hole injecting layer. The low polymer concentration and requirement for aromatic solvent presented challenges for the process; conventional photopolymer printing plates degraded rapidly on contact with xylene and rubber printing plates were found to be sufficiently resilient. Through optimisation of printing parameters and surface modification of both the printing plate and substrate with UV/ozone exposure, a consistent sub-100 nm film was achieved. Flexographic printing will enable a substantial reduction in layer fabrication time, as well as allowing roll to roll mass production at lower cost. The research indicated within this paper will aid the progression of flexography as a viable cost effective method for OLED or display technology application through continuous printing of ultra-thin layers

Recent advances in solid-state organic lasers

Organic solid-state lasers are reviewed, with a special emphasis on works published during the last decade. Referring originally to dyes in solid-state polymeric matrices, organic lasers also include the rich family of organic semiconductors, paced by the rapid development of organic light emitting diodes. Organic lasers are broadly tunable coherent sources are potentially compact, convenient and manufactured at low-costs. In this review, we describe the basic photophysics of the materials used as gain media in organic lasers with a specific look at the distinctive feature of dyes and semiconductors. We also outline the laser architectures used in state-of-the-art organic lasers and the performances of these devices with regard to output power, lifetime, and beam quality. A survey of the recent trends in the field is given, highlighting the latest developments in terms of wavelength coverage, wavelength agility, efficiency and compactness, or towards integrated low-cost sources, with a special focus on the great challenges remaining for achieving direct electrical pumping. Finally, we discuss the very recent demonstration of new kinds of organic lasers based on polaritons or surface plasmons, which open new and very promising routes in the field of organic nanophotonics

Vive le quinquina et la coca réunis !

Bernanose André. Vive le quinquina et la coca réunis !. In: Revue d'histoire de la pharmacie, 79ᵉ année, n°289, 1991. p. 164

Vive le quinquina et la coca réunis !

Bernanose André. Vive le quinquina et la coca réunis !. In: Revue d'histoire de la pharmacie, 79ᵉ année, n°289, 1991. p. 164