Structurally integrated organic light emitting device-based sensors for gas phase and dissolved oxygen

Area of Science:

• Materials Science
• Analytical Chemistry
• Sensor Technology

Background:

• Photoluminescence (PL)-based oxygen sensors offer sensitive detection methods.
• Integrating light sources with sensing elements can create compact devices.
• Organic light-emitting diodes (OLEDs) provide efficient and tunable light sources for excitation.

Purpose of the Study:

• To develop and characterize a compact, integrated photoluminescence-based oxygen sensor.
• To utilize an organic light-emitting device (OLED) as the excitation light source.
• To evaluate sensor performance in gas and various liquid phases.

Main Methods:

• Fabrication of structurally integrated sensor devices with back-to-back thin films.
• Utilizing oxygen-sensitive dyes like Pt-octaethylporphyrin (PtOEP) and Pd-octaethylporphyrin (PdOEP) in polystyrene matrices or solutions.
• Employing green and blue OLEDs for excitation of porphyrin and Ru(dpp) based sensing elements, respectively.
• Monitoring oxygen levels by measuring changes in PL lifetime (tau) of the dyes.

Main Results:

• Achieved high gas-phase detection sensitivities (S(g)) of approximately 35-50 for PtOEP and over 200 for PdOEP with an Alq3 OLED.
• Demonstrated dissolved oxygen (DO) detection sensitivities (S(DO)) of approximately 9.5 in water and 11 in ethanol using PtOEP film.
• Evaluated sensor performance including dynamic range, gas flow rate, and temperature effects, noting sensitivity dependence on film preparation and dye concentration.

Conclusions:

• The developed integrated OLED-based PL sensor offers a compact and sensitive platform for oxygen detection.
• PtOEP and PdOEP dyes exhibit excellent performance, with PdOEP showing particularly high gas-phase sensitivity.
• The sensor is effective for monitoring oxygen in both gas and liquid environments, with potential for array-based applications.