Electrically Sensitive Plasmonic Photonic Crystals for Dynamic Upconversion Manipulation

Local optical field modulation using plasmonic materials or photonic crystals provides a powerful strategy for enhancing upconversion emission of lanthanide-doped upconversion nanocrystals (UCNPs). However, it is restricted to static UC enhancement and the corresponding dynamic modulation of UC is yet to be reported, limiting its practical applications in information devices. Here, a dynamic UC modulation system is reported through electric stimulation by integrating UCNPs with electrically sensitive WO3-x plasmonic photonic crystals (PPCs). The tunable emission enhancement of UCNPs varying from five to 26 folds is achieved in WO3-x PPCs/UCNPs hybrids through external electric stimulation within +1.6 and -1.6 V. It stems from the reversible control of the photonic bandgaps and localized surface plasmon resonance of WO3-x PPCs, ascribed to the variation of refractive index and oxygen vacancy of WO3-x, induced by the reversible change of atomic ratio of W5+ to W6+ under different applied voltages. Moreover, the electrically triggered information encryption devices are developed, employing a programmable logic gate array based on WO3-x PPCs/UCNPs with the ability to convert information-encrypted electrical signals into visible patterns. These observations offer a new attempt to manipulate the UC and will simulate the new applications in the display and optical storage devices.