Record‐High Responsivity and High Detectivity Broadband Photodetectors Based on Upconversion/Gold/Prussian‐Blue Nanocomposite

Abstract

The development of high-quality and strongly Au conjugated upconversion nanoparticles (UCNPs) is time-consuming and requires specific chemicals. Therefore, a one-pot hydrothermal method is adopted for novel in situ preparation of UCNP@Au composites using a binary functional ethylenediaminetetraacetic salt, which is employed as a surfactant and reducing agent. The composites are electrostatically conjugated with metal-coordinated Prussian blue (PB) to yield UCNP@Au+PB nanocomposites (NCs), which demonstrate 21-fold upconversion emission quenching by fluorescence resonance energy transfer compared to UCNPs. Additionally, the PB, UCNP@Au, and NCs demonstrate a synergistically reduced trap (α ≈ 0.85) and enhance ultrasensitive broadband (432-980 nm) photodetection. The NCs-based gate-free epitaxial graphene device demonstrates excellent high photoresponsivity (5.9 × 10 5 A W -1 ), detectivity (2.17 × 10 14 cm H W Z 1 − − ), and normalized gain (2.06 × 10 −4 m 2 V -1 ) at 318 nW cm -2 (532 nm) and a bias voltage of 1 V. The Au plasmons enhance the one-photon-enabled visible absorption of Er 3+ ions, and PB exhibits broad absorption and enhances the carrier density of the device, resulting in an ultrahigh photoresponse. The obtained device performance is the highest to date among their class of nanohybrids. Also, these NCs can readily detect polychromatic light and signals from daily-use appliances, indicating their potential for applications in consumer electronics.

Enhanced Photoresponsivity of Perovskite QDs/Graphene Hybrid Gate‐Free Photodetector by Morphologically Controlled Plasmonic Au Nanocrystals

“…Engineering-driven photodetectors play an important role in various scientific and industrial applications, including nanomaterials, for example, PbS, ZnO, upconversion nanoparticles, and PQDs. [25][26][27][28][29] Recently, Wu et al [30] and Pan et al [27] reported PQDs/MoS 2 , and PQDs/Gr-based hybrid photodetectors with a responsivity of 7.7 × 10 4 and 1.15 × 10 5 AW -1 , respectively. Bera et al [28] demonstrated the responsivity of ≈10 9 A W -1 with Gr/PQDs/Gr-based hybrid phototransistors with a vertical structure with the shortest channel length.…”

Tuning Near‐Infrared‐to‐Ultraviolet Upconversion in Lanthanide‐Doped Nanoparticles for Biomedical Applications

“…Efficient NIR-to-UV upconversion also requires precise doping of the lanthanide ions in high-quality crystalline particles. The synthesis can now be routinely achieved by several complementary strategies including co-precipitation, [25] thermal decomposition, [26] hydrothermal synthesis, [27] and sol-gel pro-cessing. [28] In particular, co-precipitation and thermal decomposition methods carried out in organic solvents can give access to the core-multishell nanoparticles with accurate control over shell thickness and particle morphology, [16,29] thus, enjoying common usage by the community.…”

Simultaneous 980 and 800 nm Orthogonal Upconversion and Ligand-Sensitized Downshifting of Triply Excited and Multicolor-Emitted Core–Multishell Nanocrystals for High-Level Anticounterfeiting Applications

“…Lanthanides possess unique optical characteristics due to their intra 4f–4f transitions, resulting in color specificity and sharp emission bands. − Ln-based NCs demonstrate both Stokes (downshifting, DS) and anti-Stokes (upconversion, UC) emission processes, depending on the sensitizer and activator ions . Ln-based NCs can be excited under UV light (254 or 350 nm) or NIR light (800, 980, and 1550 nm). − For example, in the UC process, Er (green and red), Tm (blue), and Ho (green and red) ions serve as activators, with Yb and Nd acting as sensitizers for excitations of wavelengths 980 and 800 nm, respectively .…”