Broadband Plasmonic Antenna Enhanced Upconversion and Its Application in Flexible Fingerprint Identification

摘要

Plasmonic antennas based on metallic nanostructures that can trap longwavelengthrnlight can be used to substantially enhance the efficiency ofrnoptoelectronic devices by utilizing light beyond the visible region. This studyrnexperimentally and theoretically demonstrates that a silver nanowire networkrn(AgNW-net) plasmonic antenna exhibits superwide surface plasmon extinctionrnbecause of the strong plasmon coupling between AgNWs, providing thernability to trap light spanning the entire solar spectrum. As a proof-of-conceptrndemonstration, the AgNW-net is used to greatly improve the luminescencernof lanthanide-doped upconversion nanocrystals (UCNCs) under dual wavelengthrnexcitation and the periodic alternating multilayer structure of AgNWs/rnUCNCs is further successfully introduced to improve the absolute luminescencernintensity of AgNWs/UCNCs composite films. Furthermore, evidencernhas been provided that this improvement is attributable to excitation fieldrnenhancement rather than Purcell effect or plasmon-enhanced energy transfer.rnFinally, an upconversion flexible fingerprint identification technology is developedrnbased on AgNW-net/UCNCs/polyvinyl alcohol composite materials,rnwhich allows us extracting fingerprints on various uneven bending surfaces.