Cooperative radiation and stimulated emission at high excitation densities in poly(para-phenylene)-type ladder polymer

被引：3

作者：

Kranzelbinder, G ^{[1
]}

Graupner, W ^{[1
]}

Mullen, K ^{[1
]}

Scherf, U ^{[1
]}

Leising, G ^{[1
]}

机构：

[1] Graz Tech Univ, Inst Festkorperphys, SFB Elektroakt Stoffe, A-8010 Graz, Austria

来源：

OPTICAL PROBES OF CONJUGATED POLYMERS | 1997年 / 3145卷

关键词：

time-resolved fast spectroscopy; photoluminescence; stimulated emission; biexcitons; conjugated polymers;

D O I：

10.1117/12.284151

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

We have studied the radiative recombination processes in poly( para-phenylene)-type ladderpolymer films using ultrafast spectroscopy techniques at excitation densities up to similar to 5 x 10(20) photons/cm(3) per pulse. In addition to the vibronic manifold of singlet exciton emission the photoluminescence spectrum at such elevated conditions is characterised by an optical transition, which is not present at low pump fluence. This spectral new component is identified as biexcitonic radiative recombination, an assignment that is supported by the hyperlinearity of its total emission as a function of pump intensities and the kinetics revealing a thermal equilibrium state between excitonic and biexcitonic populations. The biexciton binding energy is evaluated to E-b,E-xx = 120 meV. Stimulated emission in the spectral blue region is investigated by femtosecond pump and probe experiments.

引用

页码：48 / 56

页数：9