Huge upconversion luminescence enhancement by a cascade optical field modulation strategy facilitating selective multispectral narrow-band near-infrared photodetection

Ji et al. Light: Science & Applications (2020)9:184 https://doi.org/10.1038/s41377-020-00418-0 ARTICLE Official journal of the CIOMP 2047-7538 www.nature.com/lsa Open Access Huge upconversion luminescence enhancement by a cascade optical field modulation strategy facilitating selective multispectral narrow-band near-infrared photodetection 1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; Yanan Ji1, Wen Xu1, Nan Ding1, Haitao Yang1, Hongwei Song1, Qingyun Liu2, Hans Ågren2, Jerker Widengren3 and Haichun Liu2,3 Abstract Since selective detection of multiple narrow spectral bands in the near-infrared (NIR) region still poses a fundamental challenge, we have, in this work, developed NIR photodetectors (PDs) using photon upconversion nanocrystals (UCNCs) combined with perovskite films. To conquer the relatively high pumping threshold of UCNCs, we designed a novel cascade optical field modulation strategy to boost upconversion luminescence (UCL) by cascading the superlensing effect of dielectric microlens arrays and the plasmonic effect of gold nanorods, which readily leads to a UCL enhancement by more than four orders of magnitude under weak light irradiation. By accommodating multiple optically active lanthanide ions in a core-shell-shell hierarchical architecture, developed PDs on top of this structure can detect three well-separated narrow bands in the NIR region, i.e., those centered at 808, 980, and 1540 nm. Due to the large UCL enhancement, the obtained PDs demonstrate extremely high responsivities of 30.73, 23.15, and 12.20 A W−1 and detectivities of 5.36, 3.45, and 1.91 × 1011 Jones for 808, 980, and 1540 nm light detection, respectively, together with short response times in the range of 80–120 ms. Moreover, we demonstrate for the first time that the response to the excitation modulation frequency of a PD can be employed to discriminate the incident light wavelength. We believe that our work provides novel insight for developing NIR PDs and that it can spur the development of other applications using upconversion nanotechnology. Introduction Narrow-band near infrared (NIR) photodetectors (PDs) capable of simultaneously detecting light in multispectral bands, e.g., in the NIR I and NIR II regions, are attracting substantial attention in diverse areas, including biological analysis, multicolor bioimaging/sensing, and encrypted communications1–4. Currently, the major technologies for multispectral NIR PDs concentrate on integrating Correspondence: Wen Xu () or Hongwei Song () or Haichun Liu () 1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 130012 Changchun, China 2 Department of Theoretical Chemistry and Biology, KTH Royal Institute of Technology, SE-106 91, Stockholm, Sweden Full list of author information is available at the end of the article multiple NIR-response materials with different bandgaps, e.g., HgCdTe (MCT), quantum wells, superlattices, two-dimensional metal chalcogenides and lanthanide upconversion nanocrystals (UCNCs)5–12. Among other materials, UCNCs, due to their unique two-photon or multiphoton excitation nature, nontoxic characteristics and low preparation cost13–18, have emerged as a superior solution by converting NIR photons into easily detectable visible photons. However, they have a relatively high pumping threshold to realize detectable upconversion luminescence (UCL), which originates from the lower absorption cross section of 4fn-4fn transitions of rare earth (RE) ions and lower luminescent quantum efficiency of UCNCs because of the anti-Stokes © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Ji et al. Light: Science & Applications (2020)9:184 nature and poses a fundamental limitation for weak NIR light detection in photoelectric devices19. In the past, a few approaches have been explored to boost UCL and decrease the pumping threshold of UCNCs, e.g., nanocrystal surface passivation, photonic crystal engineering, plasmon/organic antennas, and superlensing effects19,20. Among other techniques, utilizing the localized surface plasmon resonance (LSPR) of noble-metal nanostructures and the superlensing effect of dielectric optical microstructures can serve as two efficient strategies to take advantage of the highly nonlinear response of UCNCs to excitation intensity21–26. Although significant UCL enhancements (up to four orders of magnitude in some extreme cases) can potentially be achieved by using these optical amplifiers27, the UCL enhancement is strictly limited by localization of the hotspot induced in the light field, which is typically much smaller than the dimensions of the UCNCs. A large UCL enhancement requires delicately designed plasmonic nanostructures or dielectric optical microstructures, which would require obstructive fabrication technology and cost. Wisely designing the hierarchical structure of UCNCs to integrate multiple types of lanthanide ions into single nanoparticles can potentially achieve the detection of multispectral bands. Nevertheless, finding a practical way to separate detectable channels to decode more information is still very challenging in such PDs if one wants to avoid complicated optical system design and integration, e.g., employing additional spectral components. In this work, to overcome the shortcomings of individual amplifiers, we explored a novel cascade optical field modulation strategy integrating the superlensing effect of polymeric microlens arrays (MLAs) and the plasmonic effect of gold nanorods (Au NRs) to boost UCL. This cascade modulation strategy readily led to a UCL enhancement of more than four orders of magnitude. Such huge UCL enhancement enabled us to break through the bottleneck of UCNC-based photodetection technology and build high-performance NIR PDs with extremely high responsivity and detectivity. We designed and synthesized multi-wavelength responsive core-shellshell (CSS)-structured UCNCs that emit visible light under excitation at 808, 980, or 1540 nm and constructed NIR PDs on top. Realizing that each UCNC constitutes an information-rich kinetic system exhibiting characteristic respon (...truncated)