Graphene/Poly(methyl Methacrylate) Heterostructure-Gated Flexible Organic Light-Emitting Transistors

Organic light-emitting transistors (OLETs) are possibly the smallest integrated optoelectronic devices and have great potential for next-generation wearable intelligent display technology. A flexible and transparent gate/dielectric heterostructure is basically required for the gate modulation of luminescence. Here, a large-area graphene/poly(methyl methacrylate) (PMMA) heterostructure film is produced by a centrifugal casting (CC) and ozone treatment strategy. The CC process enables the film to be highly uniform with coefficients of variation (CV) of 2.66, 0.52, 0.61, and 0.104% for PMMA thickness, sheet resistance, optical transmittance@550 nm wavelength, and dielectric constant, respectively, which are significantly superior to those prepared by the commonly used spin-coating method. The ozone treatment effectively reduces the surface roughness and improves the surface compatibility, facilitating the deposition of an organic emissive channel layer with high photoluminescence intensity. On this basis, flexible graphene/Oz-PMMA heterostructure-gated single-layer OLET is demonstrated with effective gate modulation of luminescence. A maximum external quantum efficiency (EQE_MAX) of 7.53% and maximum luminance of more than 20,000 cd m^–2, reaching on par with the best rigid devices of the same planar structure. Moreover, the performance of the OLET devices is highly consistent with a CV of EQE_MAX of only 2.5%, laying the foundation for future large-scale practical applications. The study provides an ideal gate/dielectric platform for the production of flexible integrated optoelectronic devices.