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Photoluminescence of poly(N-vinylcarbazole) thin films deposited by dip-coating technique

Rębarz M., Dalasiński P., Bała W., Łukasiak Z., Wojdyła M., Kreja L.

Optica Applicata

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2005

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Vol. 35, nr 3

407-412

EN

This paper is concerned with the photoluminescence (PL) study of poly(N-vinylcarbazole) (PVK) thin films deposited on the glass substrate by the dip-coating method. The PL spectra have been measured under steady state excitation (He-Cd laser, 325 nm) in the temperature range from 13 to 300 K. All the samples being studied exhibit strong luminescence in broad temperature range. The main emission PL peak has maximum at 410 nm and is attributed to the excimer emission of PVK. We have observed a small red-shift of this peak with an increase of temperature. In all the films under investigation the thermal quenching of PL has been noticed. This behaviour is determined by the closeness of carbazole groups belonging to neighbouring chains because the interaction between them leads to nonradiative transitions. The PL spectra of PVK thin films annealed under iodine atmosphere have also been investigated. We have observed a decrease of PL for these films. We have concluded that the annealing of PVK under iodine atmosphere induces its degradation.

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Photoluminescence, optical transmission and reflection of Alq₃ layers obtained by thermal evaporation deposition

Dalasiński P., Łukasiak Z., Rębarz M., Wojdyła M., Bratkowski A., Bała W.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

429-434

EN

In this paper we present the photoluminescence emission spectra (PL), photoluminescence excitation spectra (PLE), transmission (TS) and reflection (RS) spectra of tris(8-hydroxyquinoline) aluminum(III) (Alq₃) layers grown by thermal evaporation deposition method. All investigated samples exhibit strong luminescence in the wide temperature range from 13 K to room temperature and for different energies of excitation. In our experiments, we have focused on temperature dependence of photoluminescence. The thermal quenching of PL in the measured samples has been found. We have observed also distinct oscillations from reflection and transmission measurements. The energies of thermal activation estimated by means of configuration coordinate diagram and also the layer thickness and refractive index are presented.

3

Photoluminescence characterization of vacuum deposited PTCDA thin films

Bała W., Łukasiak Z., Rębarz M., Dalasiński P., Bratkowski A., Bauman D., Hertmanowski R.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

445-448

EN

We investigated photoluminescence (PL) under steady state excitation and photoluminescence excitation (PLE) spectra of thin 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) films deposited on (001)Si substrate with various layer thicknesses grown at different substrate temperatures. The PL and PLE spectra have been measured at various temperatures, ranging from 10 K to 325 K. The PTCDA films exhibit strong luminescence at all mentioned ranges of temperature and for different values of excitation energy. The vibronic structure of PL spectra is clearly resolved at different temperatures. The position of peaks on energy scale depends on the temperature. We have observed a blue-shift of peaks with the decrease in the temperature. In all the investigated samples, the thermal quenching of PL has been observed. Analysis of the temperature dependence of the intensity bands, their position and full width half maximum (FWHM) allowed to find the energy barriers between the excited state and defect state. We propose a schematic potential energy diagram which explains mechanism of PL recombination