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Photodetectors have gained increasing interest in both academic and industrial domains in a ranging number of applications, including image sensing, communications, environmental monitoring and chemical/biological detection. Noble metal nanoparticles exhibit surface plasmons (SPs) associated with the enhancement of a local electromagnetic field surrounding the metal surface, leading to enhanced light absorption. Herein, size-controlled silver nanoparticles (AgNPs), gold nanoparticles (AuNPs) and gold nanorods (AuNRs) have been introduced into polymer photodiodes. The evaluated devices exhibit remarkable photocurrent enhancement at corresponding plasmon resonant wavelengths, directly resulting in a photosensitivity increase. When compared with a pristine photodiode, AgNPs-, AuNPs- and AuNRs-mediated devices reveal maximum enhancements of 46, 49 and 65% for responsivity and 39, 30 and 54% for detectivity for blue (450 nm), green (525 nm) and red (620 nm) light detection, respectively. The linear dynamic range of plasmon-mediated devices and their photoresponse stability have been further explored. The mechanism of plasmon-enhanced photocurrent has been analyzed using steady-state and time-resolved fluorescence measurements. The results indicate that plasmonic structures incorporated into polymer photodetectors can significantly improve the photoresponse in their plasmon resonant regions. This contribution is believed to showcase the effectiveness and attainable wavelength-selectable photodetection by tailoring the size and shape of coupled plasmonic nanostructures.

Harvesting low-energy photons by strategically exploiting the photocatalytic properties of plasmonic and upconversion nanocomponents is a promising route to improve solar energy utilization. Herein, a rationally designed 3D composite photoanode integrating NIR-responsive upconversion nanocrystals (UCNs) and visible-responsive plasmonic Au nanoparticles (NPs) into 3D TiO2 inverse opal nanostructures (Au/UCN/TiO2) has been shown to extend the solar energy utilization in the UV–vis–NIR range. The NIR-responsive properties of NaYF4:Yb3+-based UCNs doped with Er3+ or Tm3+ ions, and the effect of an alternating sequential introduction of UCN and Au, have been assessed. With an extended overlap between the emission of Er-UCN and the characteristic SPR band of Au, our ternary Au/Er-UCN/TiO2 hybrid nanostructure unveiled a notable 10-fold improvement in photocurrent density under UV–vis–NIR illumination compared with a pristine TiO2 reference. The Au incorporation was confirmed to play a key role in enhancing the efficiency of light harvesting and to synergistically facilitate the energy transfer from UCNs to TiO2. This work further dissected plausible mechanistic pathways combining collected photoelectrocatalytic results, with electrochemical impedance measurements and transient absorption spectroscopic measurements. The synthesis and catalytic performance of our Au/UCN/TiO2 and the underlying mechanism here proposed are expected to reflect extended applicability in analogous applications for efficient solar-to-energy sustainable platforms.

Well-defined ordered arrays of plasmonic nanostructures were fabricated on stretchable substrates and tunable plasmon-coupling-based sensing properties were comprehensively demonstrated upon extension and contraction. Regular nanoprism patterns consisting of Ag, Au and Ag/Au bilayers were constructed on the stretchable polydimethylsiloxane substrate. The nanoprisms had the same orientation over the entire substrate (3 × 3 cm2) via metal deposition on a single-crystal microparticle monolayer assembly. The plasmonic sensor based on the Ag/Au bilayer showed a 6-fold enhanced surface enhanced Raman scattering signal under 20% uniaxial extension, whereas a 3-fold increase was observed upon 6% contraction, compared with the Au nanoprism arrays. The sensory behaviors were corroborated by finite-difference time-domain simulation, demonstrating the tunable electromagnetic field enhancement effect via the localized surface plasmon resonance coupling. The advanced flexible plasmonic-coupling-based devices with tunable and quantifiable performance herein suggested are expected to unlock promising potential in practical bio-sensing, biotechnological applications and optical devices.