Barrier Performance of CVD Graphene Films Using a Facile P3HT Thin Film Optical Transmission Test

Figure 1

(a) Sample architectures for P3HT film (i), P3HT encapsulated with Cytop™ (ii), P3HT/PMMA (spin-cast) encapsulated with Cytop (iii), and P3HT with transferred multilayer graphene encapsulated with Cytop (iv). All structures were prepared using a proprietary seal. (b) Degradation rate of the P3HT film as a function of time with encapsulating Cytop (P3HT/Cytop, squares) and without encapsulating Cytop (Bare P3HT, circles). P3HT degradation of 100% refers to fully degraded P3HT film in a given sample, when no further change in P3HT transmission is observed (both for bare P3HT and P3HT/Cytop). Bare P3HT film as a control sample is used in each set of measurements during photodegradation under the fluorescent lamp. (c) P3HT degradation as a function of time for P3HT with spun-cast PMMA and encapsulated with Cytop (P3HT/PMMA/Cytop, circles) and P3HT with transferred multilayer graphene encapsulated with Cytop (P3HT/multilayer graphene/Cytop, squares). The tests and sample storage were done under ambient conditions ensuring uniformity in the intensity of the light source. (d) Raman spectra of multilayer graphene transferred on a Si-substrate which indicates presence of G and 2D bands and lack of any defect (D) band. The ratio is ~0.83; full width at half maximum (FWHM) of the 2D band is ~55 cm⁻¹ indicative of multilayer graphene. (e) UV-Vis spectroscopy of the multilayer graphene shows approximately 84% transmittance at 550 nm wavelength, suggesting presence of multilayer graphene film. Multilayer graphene film transferred to a PET substrate (insert).

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