Blue luminescent isolated Alq3 molecules in a solid-state matrix

Abstract

Thin vacuum deposited films of aluminum tris(8-hydroxyquinolinate) (Alq3) embedded in SiO2 matrix at concentrations corresponding to a single-molecule distribution are investigated. The spectral properties of the films are studied by luminescence spectroscopy. It is established that the dilution of Alq3 in the matrix leads to blueshift of the luminescence maximum up to 0.28eV compared to pure Alq3 layers. In contrast to the recently reported facial isomer of Alq3 in the crystalline δ phase, we conclude from our spectral data the observation of facial isomer molecules.

The origin of luminescence blueshifts in Alq3 composites

“…However, the existence of the fac isomer was not excluded as a minority form. In the case of SiO 2 matrix [11] only PL spectroscopy was performed, and it was found that the decreasing of concentration of Alq 3 is accompanied by a blueshift in the emission, even more consistent than the one found in Ar matrix. From the blueshift and effects due to the matrix evaporation rate, it was concluded that the mixed film of Alq 3 and SiO 2 contains both fac and mer isomers in consistent amounts.…”

“…Further studies along this line of research have been performed by using the matrix-isolation method, which consists in trapping the molecules under scrutiny inside a solid matrix, where they can be observed by means of various spectroscopic techniques at very little interaction with their environment. In particular, cold Ar [10] and room temperature SiO 2 [11] matrices have been used to measure carefully infrared and photoluminescence (PL) spectra of so trapped Alq 3 molecules.…”

Optical modes in wavelength-sized organic microcavity structures

“…A first 5.5 pair dielectric mirror consisting of alternating layers of TiO 2 and SiO 2 is deposited on a glass substrate by electron beam evaporation under high vacuum conditions (8 × 10 −6 mbar with a partial pressure of 2 × 10 −4 mbar of O 2 ). This distributed Bragg reflector (DBR) is designed for a wavelength of 535 nm, matching the emission maximum of the applied organic dye Alq 3 (Levichkova et al 2006). Following the first evaporation process, we attach a mask to the sample surface, using a variety of shapes from round to quadratic and hole diameters between 1 and 8 µm.…”

Photo and electroluminescence of a solution processable silane modified Alq3 composite showing bluish green emission

“…Flexibility, large area emitting and high efficiency are the most important keys for developing interests to make such systems [4][5][6]. Attempts have been recently done on the synthesis and use of a variety of novel electroluminescent (EL) materials for the construction of reliable OLEDs which can be highly suitable in different aspects like quantum efficiency, charge carrier mobility, thermal stability and processability [7][8][9].…”