Sensitivity gains in chemosensing by lasing action in organic polymers

Area of Science:

• Materials Science
• Analytical Chemistry
• Sensor Technology

Background:

• Societal security demands enhanced sensitivity in chemical and biological sensors.
• Semiconducting organic polymers (SOPs) are promising amplifying materials due to exciton transport.
• SOPs show potential for lasing but are limited by optical damage susceptibility.

Purpose of the Study:

• To develop highly sensitive sensors for explosive vapor detection.
• To leverage the nonlinear characteristics of SOPs for improved sensing capabilities.
• To overcome the optical damage limitations in SOP-based lasing applications.

Main Methods:

• Development of a transducing polymer with high thin-film quantum yield and optical damage threshold.
• Optical pumping of SOP thin films near their lasing threshold.
• Measurement of sensor response to trace explosive vapors (TNT, DNT) via attenuated lasing.

Main Results:

• Attenuated lasing in SOP thin films demonstrated over 30 times higher sensitivity to explosive vapors compared to spontaneous emission.
• Trace explosive vapors (TNT, DNT) induced non-radiative deactivation pathways, competing with stimulated emission.
• Sensitivity enhancement was most pronounced near the lasing threshold intensity.

Conclusions:

• The developed SOP transducing polymer exhibits a record low lasing threshold and high optical damage threshold.
• The cessation of lasing action in response to explosive vapors provides a highly sensitive detection mechanism.
• Combining amplifying materials with lasing offers a pathway to unprecedented sensitivity in explosive detection sensors.