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Title: Oxygen and relative humidity monitoring with films tailored for enhanced photoluminescence

In this study, approaches to generate porous or doped sensing films, which significantly enhance the photoluminescence (PL) of oxygen optical sensors, and thus improve the signal-to-noise (S/N) ratio, are presented. Tailored films, which enable monitoring the relative humidity (RH) as well, are also presented. Effective porous structures, in which the O2-sensitive dye Pt octaethylporphyrin (PtOEP) or the Pd analog PdOEP was embedded, were realized by first generating blend films of polyethylene glycol (PEG) with polystyrene (PS) or with ethyl cellulose (EC), and then immersing the dried films in water to remove the water-soluble PEG. This approach creates pores (voids) in the sensing films. The dielectric contrast between the films’ constituents and the voids increases photon scattering, which in turn increases the optical path of the excitation light within the film, and hence light absorption by the dye, and its PL. Optimized sensing films with a PEG:PS ratio of 1:4 (PEG’s molecular weight Mw ~8000) led to ~4.4× enhancement in the PL (in comparison to PS films). Lower Mw ~200 PEG with a PEG:EC ratio of 1:1 led to a PL enhancement of ~4.7×. Film-dependent PL enhancements were observed at all oxygen concentrations. The strong PL enhancement enables (i) using lowermore » dye (luminophore) concentrations, (ii) reducing power consumption and enhancing the sensor’s operational lifetime when using organic light emitting diodes (OLEDs) as excitation sources, (iii) improving performance when using compact photodetectors with no internal gain, and (iv) reliably extending the dynamic range.« less
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Ames Lab., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  3. Iowa State Univ., Ames, IA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0003-2670; PII: S0003267014012902
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Analytica Chimica Acta
Additional Journal Information:
Journal Volume: 853; Journal Issue: C; Journal ID: ISSN 0003-2670
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States
47 OTHER INSTRUMENTATION O2 sensor; porous sensing films; photoluminescence enhancement; light scattering; relative humidity effect