Sensitivity gains in chemosensing by lasing action in organic polymers

Publication Type:

Journal Article

Source:

Nature, nature.com, Volume 434, Issue 7035, p.876-879 (2005)

ISBN:

0028-0836

Keywords:

2005, 2013 and earlier

Abstract:

Societal needs for greater security require dramatic improvements in the sensitivity of chemical and biological sensors. To meet this challenge,
increasing emphasis in analytical science has been directed towards
materials and devices having highly nonlinear characteristics;
semiconducting organic polymers (SOPs), with their facile excited state
(exciton) transport, are prime examples of amplifying materials. SOPs have
also been recognized as promising lasing materials, although the
susceptibility of these materials to optical damage has thus far limited
applications. Here we report that attenuated lasing in optically pumped
SOP thin films displays a sensitivity to vapours of explosives more than
30 times higher than is observed from spontaneous emission. Critical to
this achievement was the development of a transducing polymer with high
thin-film quantum yield, a high optical damage threshold in ambient
atmosphere and a record low lasing threshold. Trace vapours of the
explosives 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT)
introduce non-radiative deactivation pathways that compete with stimulated
emission. We demonstrate that the induced cessation of the lasing action,
and associated sensitivity enhancement, is most pronounced when films are
pumped at intensities near their lasing threshold. The combined gains from
amplifying materials and lasing promise to deliver sensors that can detect
explosives with unparalleled sensitivity.