Gap‐Plasmon Coupled Nanopillar Array to Promote Upconversion Luminescence

This work theoretically explored the well-defined nanogap arranged as an upconversion (UC)/gold capping layer photonic nanopillar array on a back-reflecting film-coated Si substrate. The gap-plasmon (GP)-coupled periodic nanopillar array with encapsulating the upconversion layer (denoted as GPNA) is suggested to promote the upconversion luminescence (UCL) intensity at excitation and emission wavelengths. The optical localized-plasmon properties of the GPNA platform were probed by finite-difference time-domain (FDTD) method. With tweaking the geometric design parameters such as a cap thickness and gap distance, the GPNA platform can induce a prominent GP mode between the UC cap layer, thus leading to the significant plasmon-driven optical electromagnetic field amplification within the UC layer followed by substantial light absorption and UCL promotion. This proposed GP-coupled nanopillar array would pave the alternative way for a broad range of plasmon-sensitized applications which are able to absorb the incident excitation and resultant emission light. Appendix S1. Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.