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Measured J-V curves in phosphorescent OLEDs with and without Au NRs (a) over a wide voltage range of 4 V-11 V and (b) under a low voltage region of 4 V-7 V. Inset of (a) and (b) are the J-E curves and leakage current-voltage curves, respectively.
Source publication
In this manuscript we investigated the influence of Au
nanoparticles on electrical and electroluminescent (EL) performances in organic light-emitting diodes
(OLEDs) via doping as-synthesized Au nanorods (NRs) or nanocubes (NCs) into hole transport layer (HTL). Through accurately controlling the distance between the Au NRs and the emitting layer, al...
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Citations
... A noticeable difference in PL intensity in Fig. 6 35,62,79 . We used a laser beam (λ = 375 nm, power = 0.4 W) focused onto the substrate and performed a 2D XY-scan of 50 × 50 μm 2 area with simultaneous time-resolved PL (TRPL) measurements and recorded the light intensities of each spot 20,80 . A biexponential function, I PL (t) = ∑A i exp(− t/τ i ) + y 0 , is used to fit the measured PL decay curves. ...
The photodeposition of metallic nanostructures onto ferroelectric surfaces could enable new applications based on the assembly of molecules and patterning local surface reactivity by enhancing surface field intensity. DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) is an excellent fluorescent dye and dopant material with a high quantum efficiency used for OLED displays on the market. However, how to raise the photoluminescence (PL) and reduce the lifetime of DCJTB in a substrate remain extraordinary challenges for its application. Here, we demonstrate a tunable ferroelectric lithography plasmon-enhanced substrate to generate photo-reduced silver nanoparticles (AgNPs) and achieve enhanced PL with a shortened lifetime depending on the substrate's annealing time. The enhanced PL with shortened lifetimes can attribute to the localized electromagnetic (EM) wave produced by the nanotextured AgNPs layers' surface and gap plasmon resonances. The simulation is based on the three-dimensional finite element method to explain the mechanism of experimental results. Since the absorption increases, the remarkable enhanced PL of DCJTB can attain in the fabricated periodically proton exchanged (PPE) lithium niobate (LiNbO 3) substrate. Furthermore, the proposed fabrication method demonstrates to help tune the surface EM wave distribution in the substrate, which can simultaneously achieve the significantly shortened lifetime and high PL intensity of DCJTB in the substrate. Compared with the un-annealed substrate, the PL intensity of DCJTB in the assembly metallic nanostructures is enhanced 13.70 times, and the PL's lifetime is reduced by 12.50%, respectively. Thus, the fabricated substrate can be a promising candidate, verifying chemically patterned ferroelectrics' satisfaction as a PL-active substrate.
... Being combined with other structures, such as the 'bull's-eye' antenna [71], this system can provide superior radiation characteristics. The potential of ordered nanostructures created would pave the way to mass-production of nanophotonic devices such as plasmonic sensors [72,73], pixels for next-generation displays [70,[74][75][76], hot electron sources [77,78], and highly efficient single-photon sources for photonic integrated circuits [79,80]. ...
The most significant goal of nanophotonics is the development of high-speed quantum emitting devices operating at ambient temperature. In this regard, plasmonic nanoparticles-on-mirror are potential candidates for designing high-speed photon sources. We introduce a novel hybrid nanoantenna with CdSe/CdS colloidal quantum dots based on a silver nanocube in a metal cup that presents a nanoparticle-in-cavity coupled with an emitters system. We use focused ion beam nanolithography to fabricate an ordered array of cups, which were then filled with colloidal nanoparticles using the most simple drop-casting and spin coating methods. The spectral and time-resolved studies of the samples with one or more nanocubes in the cup reveal a significant change in the radiation characteristics of quantum dots inside the nanoantenna. The Purcell effect causes an increase in the fluorescence decay rate (≥ 30) and an increase in the fluorescence intensity (≥ 3) of emitters in the hybrid nanoantenna. Using the finite element method simulations, we have discovered that the proximity of the cup's wall affects the oscillation modes of the gap plasmon, which, in turn, leads to changes in the electric field enhancement inside the nanoantenna gap. Additionally, substantial variations in the behavior of the gap plasmons at different polarizations of the exciting radiation have been revealed. The proposed nanoantenna can be useful in the development of plasmonic sensors, display pixels, and single-photon sources.
... 但是, PVK作为主体材料也有一些不足 之处, 比如, 三线态能级(E T = 2.5 eV) 较低, 无法 向蓝光激子提供有效的能量转移; 空穴传输性较 强, 导致激子在界面聚集引起激子淬灭 [11] . 效应 [12,13] . LSPR效应可以增强金属纳米粒子周围 电场强度, 从而改变附近激子的辐射或电荷的传 输, 因此被广泛地应用于各类有机、无机及钙钛矿 发光二极管中提升器件性能 [14−17] . ...
Localized surface plasmon resonance (LSPR) effect of metal nanoparticles (MNs) has been widely applied in organic light-emitting diodes (OLEDs) to improve the radiation of excitons. The LSPR wavelength and intensity of MNs and the coupling between MNs and excitons greatly affect the LSPR effect on exciton radiation. In this work, silica coated silver nanocubes (Ag@SiO2 NCs) were doped in the electron transport layer (ETL) of a solution-processed multilayered white OLED (WOLED). Due to the sharp edges and corners, Ag NCs have strong LSPR effect and can effectively enhance the radiation of nearby excitons. With an appropriate concentration of Ag@SiO2 NCs, the WOLED achieved two fold improvement in the current efficiency comparing with the control device without Ag@SiO2 NCs incorporated. The working mechanism of the Ag@SiO2 NCs based WOLED was investigated in detail. For the solution-processed OLED, excitons usually form and recombine near the interface of emission layer and electron transport layer (EML/ETL) because the commonly used host material (such as polyvinylcarbazole, PVK) has the unipolar hole transport property. So the Ag@SiO2 NCs in ETL greatly enhanced the radiation of the excitons located near the EML/ETL interface, which mostly contributed to the performance enhancement of the Ag@SiO2 NCs based WOLED. Study on a group of devices with Ag@SiO2 NCs doped in different locations indicated that Ag@SiO2 NCs in ETL showed more effective LSPR effect than those in hole injection layer. Electroluminescence and photoluminescence spectra of the WOLEDs declared that the Ag@SiO2 NCs simultaneously improved the radiation intensities of the blue and yellow excitons and helped the WOLED maintain the good chromaticity stability, which was mainly attributed to the wide LSPR wavelength range (450–650 nm) of the Ag@SiO2 NCs. The SiO2 coating layer of the Ag@SiO2 NCs played the important role in the LSPR enhanced emission. On the one hand, it formed an appropriated distance between the Ag NCs and the extions, helping to generate the strong coupling between them. On the other hand, it suppressed the effect of Ag NCs on charge trapping, keeping the stability of the carrier transport in the device. Our research demonstrate MNs can effectively improve the performance of OLEDs by carefully designing the device structure.
... First, the LSPR features of metal NPs, including the resonance wavelength and intensity, should match with the radiation properties of excitons [4]. The LSPR features of metal NPs are related to their material, shape and size [5,6]. For example, Ag NPs can excite a strong LSPR intensity at a shorter waveband due to the strong absorption of Ag [2]. ...
A blue organic light-emitting diode (OLED) with silica-coated silver nanocubes (Ag@SiO2 NCs) inserted at the hole transporting layer/emission layer interface is reported. The localized surface plasmon resonance (LSPR) properties of the Ag@SiO2 NCs was characterized by the measured absorption spectra, stable-stated and transient photoluminescence, and calculated dipole radiation power. The results suggest that the Ag NCs significantly improve the radiation intensity of the nearby excitons due to their sharp corners and edges, but have less impact on the radiation rate of the excitons. The exciton recombination zone in the blue OLED was confirmed by a group of devices with an ultra-thin yellow emission layer located at different places, which helps to figure out the distribution of the excitons around the Ag@SiO2 NCs and deeply understand the coupling between the excitons and the Ag@SiO2 NCs. In our blue OLED, an appropriate distance between the Ag NCs and the excitons is realized due to the SiO2 coating layer and the exciton distribution, which greatly improves the energy transfer between the excitons and the Ag NCs. In addition, the LSPR enhanced electric field around the Ag@SiO2 NCs improves the carrier injection at the hole transporting layer/emission layer interface and increases the current density of the blue OLED. Finally, the blue OLED with a simple triple layer structure achieved a high current efficiency of 51.1 cd/A.
... The energy transfer between the LSPR field of metal NPs and the radiation field of excitons is usually considered as a primary reason for the performance enhancement of the metal NP-based OLEDs [20,21]. In our WOLEDs with Ag@SiO 2 NCs, the energy transfer may occur between the Ag NCs and the FIrpic and PO-01 excitons. ...
Solution-processed white organic light-emitting diodes (WOLEDs) with silica-coated silver nanocubes ( Ag @ SiO 2 NCs) incorporated at the interface of a hole transporting layer and emission layer are studied. The concentration of Ag @ SiO 2 NCs is varied to investigate the effect of Ag @ SiO 2 NCs on the performances of WOLEDs. Owing to the sharp edges and corners, Ag NCs greatly improve the radiative rate and emission intensity of nearby blue excitons. The blue emission at different Ag @ SiO 2 NC concentrations determines the performance of the WOLEDs. The emission of the orange excitons is strengthened by the high concentration of Ag @ SiO 2 NCs, which slightly influences the device performance. On the other hand, the SiO 2 shell and some SiO 2 nanospheres coexisting with Ag NCs reduce the hole transporting, improving the carrier balance in the WOLEDs. The experimental and simulated results also show that excessive Ag @ SiO 2 NCs may cause a rough film surface, unbalanced carrier injection, and fluorescence quenching, which decreases the device performance. The optimized WOLED with a proper concentration of Ag @ SiO 2 NCs has a peak current efficiency of 53.9 cd/A, acquiring a significant enhancement factor of 77.3% compared to the control device without Ag @ SiO 2 NCs.
Enhancement of the spontaneous emission of fluorophores aided by plasmonic nanoparticles (PNPs) prompts the growth of plasmonic organic light emitting diodes (OLEDs). Together with the spatial dependence of the fluorophore and PNPs on enhanced fluorescence, the surface coverage of the PNPs controls the charge transport in OLEDs. Hence, here, the spatial and surface coverage reliance of plasmonic gold nanoparticles is controlled by a roll-to-roll compatible ultrasonic spray coating technique. A 2-fold enhancement in the multi photon fluorescence is seen by two-photon fluorescence microscopy for a polystyrene sulfonate (PSS) stabilized gold nanoparticle located 10 nm away from the super yellow fluorophore. Fluorescence enhancement combined with ∼2% surface coverage of PNPs, provides a 33%, 20% and ∼40% increase in the electroluminescence, luminous efficacy and external quantum efficiency, respectively.
Localized surface plasmon resonance (LSPR) field enhancement effects of noble metallic nanoparticles can be exploited to enhance the performance of diverse luminescent materials and devices, in which the spectral proximity plays an important role in increasing near-field enhancement-induced excitation (NFEE) and surface plasmon-coupled emission (SPCE) efficiencies. In this work, we propose a scheme simultaneously utilizing the transversal and longitudinal SPR bands of elongated gold nanocrystals to match with the excitation and emission wavelengths of emitters, respectively, to achieve the most efficient enhancement. To demonstrate the idea, four types of gold nanoparticles (AuNPs, diameter=20 nm), gold nanorods (AuNRs, length/width=80/40 nm; 90/30 nm) and gold nanobipyramids (AuNBPs, length/width=80/40 nm) were employed as the plasmonic nanoantennas, according to spectral characteristics of the classic poly(2-methoxy-5-(2′-ethyl-hexoxy)-1,4-phenylene-vinylene) (MEH-PPV) chosen as the emitter. Due to the double SPR bands of both AuNBPs (80/40 nm) and AuNRs (80/40 nm) overlapping well with the excitation and emission wavelengths of MEH-PPV, maximum 2.2 and 2.1 times enhancement in photoluminescence intensity was observed, respectively. This is attributed to the integrated effects of NFEE and SPCE that synchronously accelerate the excitation and radiation rate as evidenced by steady-state and time-resolved photoluminescence measurements. Further, above plasmonic nanoantennas were incorporated into the polymer light-emitting diodes (PLEDs), in which AuNBPs (80/40 nm)- and AuNRs (80/40 nm)-mediated devices exhibited approximately 2.3 and 2.1 times enhancement in luminance, and 2.0 and 1.9 times enhancement in luminous efficiency compared with the pristine one, respectively. And more notably, it is firstly demonstrated that the sharp-tip AuNBPs generating stronger local electric field compared to AuNRs can efficiently enhance PLEDs performance, showing a promising prospect for the development of high-performance red and near-infrared electroluminescence devices.
Ag nanocubes coated with SiO2 shell were synthesized and incorporated into the emission layer of blue organic light-emitting diodes to improve the device performance. The thickness of SiO2 shell was changed to adjust the distance between Ag NCs and excitons to investigate the coupling of the localized surface plasmon resonance (LSPR) of Ag NCs and the radiation of excitons. In addition, the host materials with different carrier transporting properties are used to study the correlation between the LSPR enhanced exciton radiation and the exciton recombination zone in emission layer. Research findings demonstrate the thickness of SiO2 shell and the exciton recombination zone together affect the coupling of LSPR and exciton radiation. Using the Ag NCs coated with 15 nm SiO2 shell and the bipolar host material of 2,6-bis(3-(carbazol-9-yl)phenyl)pyridine (26DCzPPy), the blue OLED achieved an very high improvement in the current efficiency. The maximum peak current efficiency of the blue OLED with Ag NCs reached to 97 cd/A, being nearly 4 times of that of the device without Ag NCs.
Metal‐containing nanomaterials have attracted widespread attention in recent years due to their physicochemical, light‐scattering and plasmonic properties. By introducing different kinds and different structures of metal‐containing nanomaterials into organic light‐emitting diodes (OLEDs), the optical properties of the devices can be tailored, which can effectively improve the luminous efficiency of OLEDs. In this review, the fundamental knowledge of OLEDs and metallic nanomaterials were firstly introduced. Then we overviewed the recent development of the optimization of OLEDs through introducing different kinds of metal‐containing nanomaterials.
