Conjugated polymer materials are at the forefront of many next-generation organic optoelectronic technologies including organic light-emitting diodes, photovoltaics and lasers. The photophysical properties of these materials can be controlled and optimized through the formation of nanoscaleconfined geometries such as nanoparticles, aggregates, nanofibers, or thin films. In this review, we discuss the photonic characteristics of conjugated polymer-based nanostructured materials and devices with a focus on how excitons and photons can be manipulated and managed though confinement of polymer chains and through interactions with inorganic nanostructures. We include case studies from the literature on how internal molecular morphology can be controlled in conjugated polymer thin-film optoelectronics, nanowires and nanofibers and, in turn, how internal morphology affects the photonic properties of these structures. Extrinsic approaches to controlling or modifying the photonic properties of conjugated polymer materials and devices through the addition of inorganic photonic nanostructures are also discussed.

B f lm/W luminous efficacy Electrical-to-optical power conversion efficiency k 0.75 correction factor Accounts for device operation at 75% of its initial luminous efficacy, on average, due to degradationand efficiency roll-off during its operational lifetime B cd/m 2 luminance Used to quantify the brightness of a lightemitting deviceper area

This work presents an experimental investigation of enhancing surface plasmon polariton coupling to semiconductor emission by tailoring metal film thickness.

Organometallic phosphors are an important class of emissive materials used in high-efficiency organic light-emitting devices. However, problems of low photostability arise for blue-emitting phosphors due to chemical and environmental degradation, and to triplet quenching processes. Various approaches have been developed to improve the photostability of such phosphors including development of new organometallic molecules and control of host-dopant composition in thin films. Here, we demonstrate a different approach to improving the photostability of blue organometallic phosphors that uses localized surface plasmon resonances to increase the triplet recombination rate. The increased recombination rate improves the photostability of the phosphor due to the reduction in triplet quenching pathways. We show that the lifetime of phosphorescence is decreased significantly by nanoparticle-based plasmonic surfaces, which improves the photostability of the blue organometallic phosphor by up to a factor of 3.6. Other plasmonic surfaces are also tested and exhibit less significant photostability improvements due to reduced spectral overlap of the plasmonic modes with the emitter and lower mode confinement. The use of plasmonic surfaces to improve phosphor photostability at blue wavelengths is distinct from other approaches because it involves modification to the local electromagnetic environment of the phosphor rather than modifications to the phosphor molecular structure or to the emitting material composition.

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