A facile approach for significantly enhancing fluorescent gas sensing by oxygen plasma treatments

Abstract Organic thin-film fluorescent probes for vapor sensing have attracted more and more attentions in recent years with the advantages of simple operations, no pollution of analytes and fast responses. Thin film with high uniformity, orderly arrangement and ultra-high specific surface area is useful to construct a good gas sensor. In the past, modulating the morphology of fluorescent films relied on concentration control or ordered templates. In this work, we proposed a simple approach to modulate surface morphologies of representative materials (S1, S2, and S3) by substrate treatment of oxygen plasma, which could significantly enhance the sensing performance of the fluorescent materials. The response time for these three materials was shortened by up to 101.6 s, 504.2 s, and 1362.2 s, respectively. The detection limits of S1, S2, and S3 for corresponding analyte were decreased by 6.2, 1.6, and 36 times. The improvement of performance was mainly because the enhanced surface free energy (from 48.38 mJ/m2 to 87.29 mJ/m2) after treatment is helpful for adhesion. This low-cost, easy-to-operate, and universal approach has the potential to function as a very efficient method for enhancing the sensing performances of thin-film fluorescent probes.