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Polymer spacer tunable Purcell-enhanced spontaneous emission in perovskite quantum dots coupled to plasmonic nanowire networks
摘要： Polymer spacer tunable Purcell-enhanced spontaneous emission in perovskite quantum dots coupled to plasmonic nanowire networks? Lead halide perovskite quantum dots (PQDs) have recently been proposed as a scalable and color-tunable quantum source, but their slow spontaneous emission creates a mismatch with high-speed nanophotonic devices. Here, we demonstrate fast and bright emission in PQD films coupled to silver nanowire networks (NWKs), in which polyvinyl alcohol (PVA) is used as a spacer to regulate the lossy characteristics of the plasmonic cavity. Compared with bare quartz, the PVA substrate shows a considerable enhancement effect on the apparent emission intensity, but a reduction in the emission rate of PQD excitons. The efficient NWK–PQD coupling generates an increase in the emission intensity of a factor of 6.0 (average 3.4) and simultaneously a 2.4-fold (average 1.9) enhancement in the emission rate. However, an opposite PVA spacer thickness dependence for Purcell factor and quantum yield is observed, indicating that the fast and bright emission would be a trade-off between the Purcell-enhanced radiative rate and large metal guidance on plasmonic cavity design for perovskite-based nanophotonic devices.
关键词： plasmonic nanowire networks,spontaneous emission,Polymer spacer,Purcell-enhanced,perovskite quantum dots
更新于2025-11-21 11:24:58
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Phase Distribution and Carrier Dynamics in Multiple-Ring Aromatic Spacers-Based Two-Dimensional Ruddlesden-Popper Perovskite Solar Cells
摘要： Two-dimensional (2D) perovskites with natural multi-quantum-well structure have been reported to offer better stability compared to 3D perovskites. However, the understanding of the exciton separation and transport mechanism in 2D perovskite as well as developing more efficient organic spacers remain considerable challenges as the 2D perovskite exhibit large exciton binding energy due to quantum confinement. Here, a class of multiple-ring aromatic ammoniums, 1-naphthalenemethylammonium (NpMA) and 9-anthracenemethylammonium (AnMA), were developed as spacers for 2D Ruddlesden-Popper (RP) perovskite solar cells (PSCs). In addition to significantly enhanced stability, the device based on (NpMA)2(MA)n-1PbnI3n+1 (average n = 4) exhibits a champion efficiency of 17.25% and a high open circuit voltage of 1.24 V. The outstanding photovoltaic performance could be ascribed to the ultrafast exciton migration (within 7 ps) from 2D phases to 3D-like phases, which were confirmed by charge carrier dynamics results, leading to efficient exciton separation, charge transportation and collection. This work facilitates understanding the working mechanism of 2D PSCs deeply and offers an efficient way to further boosting their efficiency and stability by developing multiple-ring aromatic spacers.
关键词： perovskite solar cell,organic spacer,phase distribution,charge transport,two-dimensional
更新于2025-09-23 15:21:01
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Silver Soret Nanoparticles for Femtomolar Sensing of Glutathione in a Surface Plasmon-Coupled Emission Platform
摘要： Surface plasmon-coupled emission (SPCE) has emerged as an interdisciplinary, versatile sensing platform due to its highly directional, solid-state and polarized emission. Here, we report the distinct properties rendered by Ag-Soret Colloids (Ag-SCs) such as nanovoids and nanocavities to observe 104-fold enhancement in emission intensity of omnidirectionally radiating emitter dipoles. Unlike earlier reports utilizing templated Ag-nanoparticles in spacer or cavity architectures, here we employ template-free, linker-less Ag-SCs. Purcell factor (PF - maximum of 120.6) obtained using the finite-difference time-domain (FDTD) simulations for soret nanocavities are in excellent agreement with the trend in emission enhancements obtained experimentally. Thermal gradient created by adiabatic cooling of Ag nanoparticles (AgNPs) drives their thermo-diffusion resulting in monodisperse nanoparticle assemblies (Ag-SCs). In addition, we report an extended-cavity architecture with Ag-SCs, as a novel pseudo-metal-dielectric-metal (p-MDM) interface, for achieving 80-fold SPCE. This study also features the unique properties of Ag-SCs as interfacial nanomaterials in SPCE platform to achieve femtomolar detection of glutathione (GSH). The quenching of fluorescence from alizarin red S-boric acid (ARS-BA) complex upon addition of Cu2+ ions and the dequenching upon GSH addition studied with Ag-SCs as spacer layer remarkably increased the sensitivity of the analyte. The uniform and intense electromagnetic field-confinement provided by these intricate architectures and hybrid interfaces, along with its ease of fabrication and versatility for variety of analytes, is critical to achieve augmented SPCE. This is accomplished without compromising on the reliability of detection as demonstrated with the use of a cellphone camera, CIE color space and luminosity plots for the turn-on fluorescence. The emission images were acquired using an android phone camera by aligning it with its angular emission, making it amenable for point-of-care diagnostics.
关键词： Soret colloids,Surface plasmon-coupled emission,spacer engineering,smartphone-based detection,template-free approach,fluorescence enhancement,glutathione sensing
更新于2025-09-23 15:19:57
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Investigation of newly designed asymmetric chromophore in view of power conversion efficiency improvements for organic solar cells
摘要： The organic chromophore of (D1-π-A-D2) type, (E)-4-(3,5-dimethoxystyryl)-7-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole, OMe-BBTz, was synthesized using 2,1,3-benzothiadiazole as an acceptor with dimethoxyphenyl and hexyl bithiophene as donor units for the fabrication of bulk-heterojunction organic solar cells (BHJ-OSCs). The synthesized OMe-BBTz chromophore was comprehensively analyzed through structural, thermal, electrochemical, and photovoltaic characterizations. Reasonable HOMO (-5.39 eV) and LUMO (-3.41 eV) energy levels along with the optical band gap of ~1.98 eV were observed. The power conversion efficiency (PCE) of ~3.53 % with the short circuit current density (JSC) of ~8.71 mA/cm2 and the open-circuit voltage (VOC) of ~0.698 V were achieved by BHJ-OSCs with OMe-BBTz:PC61BM (1:3, w/w) active layer.
关键词： Organic solar cells,π-spacer,Benzothiadiazole,Structural,Thin film
更新于2025-09-19 17:13:59
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Efficient Two-Dimensional Tin Halide Perovskite Light-Emitting Diodes via a Spacer Cation Substitution Strategy
摘要： Lead halide perovskites have attracted tremendous attention due to their impressive optoelectronic properties. However, the toxicity of lead remains to be a bottleneck for further commercial development. Two-dimensional Ruddlesden-Popper tin-based perovskites are lead-free and more stable compared to their 3D counterparts, which have great potential in the optoelectronic device field. Herein, we demonstrated high-quality 2D phenylethyl ammonium tin-iodide perovskite (PEA2SnI4) thin films by dropping toluene as anti-solvent. Furthermore, the PeLED performance is greatly improved by replacing PEAI spacer cation with 2-thiopheneethyllamine iodide (TEAI). As a result, the TEA-based PeLED device is achieved with a low turn-on voltage of 2.3V, a maximum luminance of 322 cd m-2 and maximum external quantum efficiency of 0.62%, which is the highest efficiency and brightness for pure red (emission peak=638 nm) tin-based PeLEDs so far.
关键词： pure red light-emitting diodes,two-dimensional tin-based perovskite,spacer cation substitution
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Influence of Spacer Thickness on the Optical Properties of Vertically Stacked InP/AlGaInP Quantum Dot Lasers at the Short Wavelength
摘要： Quantum dot (QD) based semiconductor lasers are the widely used sources in many applications. The unique advantages are their low threshold current density, high characteristic temperature, and high differential material gain, owning to their discrete energy levels. The self-assembled InP QDs in the (AlxGa1?x)0.51In0.49P (AlxGaInP) barriers are of great interests due to the emitting spectrum from 630 nm to 780 nm [1]. However, limited by the low QD density, the low energy state density, and the small optical confinement factor, a single-sheet of QD only can provide a lower optical modal gain in the laser structure, which limits the laser performances. Meanwhile, the weak charge carrier confinement of the AlGaInP material further makes the devices sensitive to the operation temperature. One of the solutions for above issues is to increase the QD density by vertically stacking the QD layers. In the stacked QDs, the spacer thickness between the QD layers is one of the critical parameters needed to be carefully considered [2]. In this report, we investigated the influence of the spacer thickness on the optical properties of the vertically stacked InP/AlGaInP QD lasers at the emitting wavelength around 660 nm. The investigated laser structures (as shown in Fig. 1(a),) were grown by metal-organic vapor-phase epitaxy (MOVPE) on n-doped (100)-GaAs substrate oriented by 6° towards the [111]A direction. The epitaxial growth was performed at the temperature of 710°C and the pressure of 100 mbar with standard precursors. From bottom to top, the laser structure contains a 100 nm-thick GaAs:Si buffer layer, followed by a 50 nm-thick GaInP:Si layer and a 1 μm-thick AlInP:Si optical confinement layer. The InP quantum dot active region was grown and placed in the center of a 2×10 nm thick Al0.10GaInP barrier, surrounded by 2×150 nm Al0.55GaInP waveguide. The p-side layers are similar to the n-side, but the dopant was changed to Zinc. Here, we compared the optical properties of three different active region structures: single QD layer, double QD layers with the spacer of 6 nm and 10 nm. The measured electrically pumped modal absorption spectra of the investigated structures by the segmented contact method are shown in Fig. 1(b). It demonstrated that the thicker spacer introduces additional internal absorption loss due to the Al-based materials of the spacer. Meanwhile, the smaller spacer structure has the higher absorption of the large QD from the upper layer, attributed to the stronger strain effect and the increasing tunnelling rate. At room temperature, it demonstrates that the measured saturated peak net modal gain values (as shown in Fig. 1(c)) are 68.5 cm?1 and 57.8 cm?1 for the 6 nm-spacer structure and 10 nm-spacer structure, respectively, which are 1.56 and 1.32 times higher than the single-layer QD laser. The higher gain value of the smaller spacer structure is also attributed to the higher tunnelling probability and the shorter tunnelling time.
关键词： optical properties,InP/AlGaInP,spacer thickness,Quantum dot,semiconductor lasers
更新于2025-09-12 10:27:22
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4-Aminoethyl Pyridine as a Bifunctional Spacer Cation for Efficient and Stable 2D Ruddlesden-Popper Perovskite Solar Cells
摘要： Two-dimensional (2D) Ruddlesden?Popper (RP) perovskites are attractive due to their appealing environmental stability. We demonstrate herein a spacer cation, 4-aminoethyl pyridine (4-AEP), for preparation of 2D RP perovskite films. The 4-AEP can not only act as a spacer cation, but also coordinate with the Pb2+ ions in PbI2 with the nitrogen atom on the pyridine ring. High-quality 2D RP perovskite films can thus be formed as the coordination interaction retards the crystallization rate of the 2D RP perovskites. As a result, the solar cell employing the (4-AEP)2MAn?1PbnI3n+1 (n=5) 2D perovskite achieves a power conversion efficiency (PCE) of 11.68% with good air stability, which is much better than the phenylethylamine spacer cation at the same conditions (PCE = 7.95%). This work provides a new idea for designing novel spacer cations towards efficient and stable 2D RP perovskite solar cells.
关键词： Two-dimensional perovskite,pyridine,spacer cation,perovskite solar cells,crystallization regulation
更新于2025-09-12 10:27:22
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Spacer layer design for efficient fully printable mesoscopic perovskite solar cells
摘要： The spacer layer is a key component of fully printable mesoscopic perovskite solar cells, but its precise characteristics are far from being understood in relation to the device design. In the present work, we perform a detailed systematic study on the effects of spacer parameters, such as size of building blocks, layer thickness, etc., on properties of the perovskite filler, insulating ability and performance of fully printable mesoscopic perovskite solar cells by combining the techniques of time-resolved photoluminescence, high-resolution TEM, insulating resistance measurements, impedance spectroscopy and J–V characteristics. Drawing on the deep understanding from these studies, we formulate key principles, which are anticipated to guide the design of the advanced spacer layer for fully printable mesoscopic perovskite solar cells.
关键词： mesoscopic perovskite solar cells,performance,insulating ability,spacer layer
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Semi-Analytic Modeling of Chiral Metasurface Stacks
摘要： Metasurfaces allow anisotropic polarization states to be designed freely from the geometry, material and distribution of their constituent subwavelength structures or particles as well as their arrangement. It was shown recently that multilayer metasurfaces can exhibit a chiral polarization response without having chiral particles or near-field induced bianisotropy. Such stacked metasurfaces couple modally in the far-field and are geometrically chiral only as a complete system, even though their constituent parts are not. In our contribution we employ a semi-analytic approach to derive a model of a chiral metasurface stack consisting of two nano-wire based metasurfaces with rotated unit cells, separated by a spacer layer. Using a fabricated sample as a basis for our discussion, we explain the origin of its polarization response and unravel the role of the spacer layer separating the two metasurfaces.
关键词： chiral metasurface,spacer layer,semi-analytic modeling,nano-wire,polarization response
更新于2025-09-11 14:15:04
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Two-state lasing at room temperature in InAs/InP quantum dots
摘要： The two-state lasing conditions at room temperature in InAs/InP quantum dot (QD) lasers under a continuous wave electrical bias current are studied. It is found that excited state (ES) lasing is promoted by moderately decreasing spacer thickness and increasing dot-size dispersion in a QD stack, and the physical origins are due to the increased bottleneck effect and inhomogeneous broadening. Moreover, it is proved theoretically that ground state (GS) lasing with high inhomogeneous broadening may result in high phase and intensity noise at a high bias current. Therefore, an appropriate spacer thickness together with appropriate inhomogeneous broadening is critical to the GS and/or ES lasing, which helps an optimal design of laser geometry.
关键词： two-state lasing,spacer thickness,room temperature,InAs/InP quantum dots,inhomogeneous broadening,dot-size dispersion,intensity noise,continuous wave electrical bias,bottleneck effect,phase noise
更新于2025-09-11 14:15:04