The role of excitons' quasiequilibrium in the temperature dependence of the poly(9,9-dioctylfluorene) β phase photoluminescence

被引:17
作者
Anni, M
Caruso, ME
Lattante, S
Cingolani, R
机构
[1] CNR, INFM, Natl Nanotechnol Lab, I-73100 Lecce, Italy
[2] Univ Lecce, Dipartimento Ingn Innovaz, I-73100 Lecce, Italy
[3] Univ Lecce, CNR, INFM, Dipartimento Fis, I-73100 Lecce, Italy
关键词
D O I
10.1063/1.2179795
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We investigated the temperature dependence of the poly(9,9-dioctylfluorene) beta phase photoluminescence (PL) spectra in spin coated thin films from tetrahydrofuran solutions. As the temperature increases from 18 to 300 K a continuous blueshift of the 0-0 PL peak of about 25 meV and an increase of the peak full width at half maximum (FWHM) of about 49 meV are observed. We show that the PL spectra temperature dependence is not due to a temperature dependent average conjugation length, as often assumed, but instead it can be quantitatively explained in the frame of a thermal quasiequilibrium model for excitons in an inhomogeneously broadened excited states distribution. We demonstrate that the emission blueshift and broadening are mainly due to the increase of the excitons' temperature with the sample one. This effect is partially compensated by an increasing efficiency of the exciton energy migration. The interplay between these two processes quantitatively explains the observed temperature dependence of the PL peak energy and of its FWHM. On the contrary we show that the PL spectra are almost independent of the absorption blueshift with temperature. (c) 2006 American Institute of Physics.
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页数:7
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