Surface plasmons limit the efficiency of organic light‐emitting diodes (OLEDs). Up to 40 % of the radiative power may be lost to surface plasmon (SP) modes associated with the metallic cathodes of OLEDs. Calculations show the importance of material selection and device geometry in this process. Experiments reveal the presence of the SP modes and suggest ways in which this power may be recovered using periodic nanostructure.

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Currently, there are no simple sensing techniques for determining in real-time both the severity and location of structural damage in a composite caused by a dynamic impact event. Materials are known which emit light when they are fractured. This fracture-induced light emission is known as triboluminescence. A triboluminescent material embedded in, or attached on, a composite structure could act as a real-time damage sensor. The occurrence and severity of the damage is given by the intensity of the resulting triboluminescent light. Since the triboluminescent light emission is fracture-initiated, no signal would be generated by a triboluminescent sensor until damage occurred. Hence no false alarms are generated by this type of sensor. An array of triboluminescent sensors may allow real-time damage location monitoring simply by determining the wavelength of the emitted light. We have developed a series of highly efficient triboluminescent materials with sufficient thermal and chemical properties to allow doping into composites. We report a series of proof-of-principle experiments with these materials which strongly support the potential of triboluminescent sensors to monitor in real-time both the magnitude and location of structural damage.