Optical amplification and stability of spiroquaterphenyl compounds and blends

Abstract

In this contribution, we present a systematic investigation on a series of spiroquaterphenyl compounds optimised for solid state lasing in the near ultraviolet (UV). Amplified spontaneous emission (ASE) thresholds in the order of 1 µJ/cm 2 are obtained in neat (undiluted) films and blends, with emission peaks at 390±1 nm for unsubstituted and meta-substituted quaterphenyls and 400±4 nm for para-ether substituted quaterphenyls. Mixing with a transparent matrix retains a low threshold, shifts the emission to lower wavelengths and allows a better access to modes having their intensity maximum deeper in the film. Chemical design and blending allow an independent tuning of optical and processing properties such as the glass transition.

Two-dimensional Wrinkle Resonators for Random Lasing in Organic Glasses

“…We follow the approach given in ref. 48 and calculate the overlap of the waveguide mode with the depth-dependent excitation density in form of a gain factor in which n active is the refractive index of the active layer, n eff the mode index, E y (x) the electric field profile of the TE mode and α ex the attenuation coefficient at the pumping wavelength of 337 nm. With an extinction coefficient k = 0.045 as imaginary part of the refractive index, α becomes 1.7·10 -3 nm −1 and is sufficiently low that the entire active zone is pumped almost homogeneously.…”

“…However, the FWHM increased with a delay between 300 pulses and 400 pulses. By encapsulating the devices to either measure under vacuum conditions or in an inert atmosphere, the reduction in intensity by degradation effects can be slowed down significantly 48 . Also, these wrinkled thin films are simple to produce under moderate conditions and it is easy to replace a bleached region by shifting the sample spatially to a pristine region, of course at the cost of selecting different spectral modes.…”

Phase Separation and Nanostructure Formation in Binary and Ternary Blends of Spiro-Linked Molecular Glasses

“…We start our study with four representatives (Figure ): Spiro-TAD , as a typical electron donor and hole transport material (HOMO level −5.0 eV), Spiro-4Φ − as a typical laser material, Spiro-PFPy as an electron acceptor and electron transport material (LUMO level −2.80 eV), and Spiro-PFT (LUMO level −2.61 eV) as an electron-accepting spiro-oligophenyl that exhibits the highest degree of fluorination. As a third component in blends, we then add Spiro-4Φ-PFT and Spiro-TAD-PFT in which each half of the spirobifluorene core is differently substituted.…”