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.
Highlights
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 communications[1,2,3,4]
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 upconversion nanocrystals (UCNCs) to excitation intensity[21,22,23,24,25,26]
Significant upconversion luminescence (UCL) enhancements can potentially be achieved by using these optical amplifiers[27], 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
Summary
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 communications[1,2,3,4]. 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 intensity[21,22,23,24,25,26]. Significant UCL enhancements (up to four orders of magnitude in some extreme cases) can potentially be achieved by using these optical amplifiers[27], 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
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