Low Temperature Physics: 38, 786 (2012); https://doi.org/10.1063/1.4740245 (6 pages)
Физика Низких Температур: Том 38, Выпуск 8 (Август 2012), c. 985-992    ( к оглавлению , назад )

Phase transitions in thermally annealed films of Alq3

G. Baldacchini

Via Guglielmo Quattrucci 246, 00046 Grottaferrata, Roma, Italy
E-mail: giuseppe.baldacchini@enea.it
giuseppe.baldacchini@gmail.com

P. Chiacchiaretta

Department of Neuroscience and Imaging, University G. D'Annunzio, 66013 Chieti, Italy

R.B. Pode

Department of Physics, Kyung Hee University, 1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, South Korea

M.A. Vincenti

ENEA, Photonics Micro- and Nano-structures Laboratory, UTAPRAD-MNF, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Rome, Italy

Q.-M. Wang

School of Chemistry and Environment, South China Normal University, Waihuan Xi Road 378, Guangzhou 510006, P. R. China 510006

Received April 12, 2012

Аннотация

Organic light emitting devices have been so very much improved lately that they are being widely applied for displays and lighting. Among many improving technologies, annealing processes in different atmospheres affect greatly their performance, for instance when the active material is the small molecule Alq3. In particular, a significant increase of the photoluminescence is observed in thin films of this molecule between 150 and 180 °C, before the physical destruction of the films occurs at higher temperatures. This phenomenon is attributed to a phase transition towards a novel morphological aggregation of the molecules in the film, which proved to be a much improved optical material for luminescent applications, and which seems common to other molecules as well.

PACS: 78.40.Me Organic compounds and polymers;
PACS: 78.55.Kz Solid organic materials;
PACS: 78.66.Qn Polymers; organic compounds;
PACS: 81.30.Hd Constant-composition solid–solid phase transformations: polymorphic, massive, and order-disorder;
PACS: 81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization.

Ключевые слова: Alq3, thin films, spectroscopy absorption, spectroscopy emission, phase transitions.