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Plasmonic device diagram and nanocube morphology a, Schematic of the plasmon NPA, with relevant layer thicknesses annotated. The EML position and width within the OLED are denoted by the green line. The chemical structures of the EML components, host (DIC-TRZ) and emitter (Ir(ppy)3), are also presented. b, Atomic-force micrograph of Ag nanocubes spun on top of the OLED. The fill fraction of Ag cubes is 15%, with a centre-to-centre spacing of ~200 nm. ITO, indium tin oxide.
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The field of plasmonics, which studies the resonant interactions of electromagnetic waves and free electrons in solid-state materials¹, has yet to be put to large-scale commercial application² owing to the large amount of loss that usually occurs in plasmonic materials³. Organic light-emitting devices (OLEDs)4–7 have been incorporated into billions...
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While monochrome organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters have achieved over 30% external quantum efficiencies (EQEs), all‐TADF white OLEDs (WOLEDs) are still lagging behind. Herein, a simple system based on two color‐complementary TADF emitters is exploited to realize high‐performance...
Citations
... In the field of plasmonics, the excitation of electrons in graphene by light in the THz to mid-infrared (IR) range is known to lead to optical graphene plasmon-polaritons [10,28,15,29], i.e. collective oscillations of the two-dimensional electron liquid in graphene [30,31], commonly referred to as Dirac plasmons [32]. In this context, significant progress has been made towards the development of new plasmon-based devices using 2D nanomaterials and graphene, driven by their vast promising applications in sensors [33], light-emitting devices [34], nano-optical systems [35,36], spectroscopy [37], molecular fingerprints [38], and radiative heat transfer [39]. Furthermore, the possibility to excite plasmons in graphene combined with different 2H-TMDs, where 2H refers to the hexagonal symmetry [20], thus forming different vdWhs, opens up innovative avenues for developing low-dimensional technologies [40]. ...
Acoustic plasmons in graphene exhibit strong confinement induced by a proximate metal surface and hybridize with phonons of transition metal dichalcogenides (TMDs) when these materials are combined in a van der Waals heterostructure, thus forming screened graphene plasmon-phonon polaritons (SGPPPs), a type of acoustic mode. While SGPPPs are shown to be very sensitive to the dielectric properties of the environment, enhancing the SGPPPs coupling strength in realistic heterostructures is still challenging. Here we employ the quantum electrostatic heterostructure model, which builds upon the density functional theory calculations for monolayers, to show that the use of a metal as a substrate for graphene-TMD heterostructures (i) vigorously enhances the coupling strength between acoustic plasmons and the TMD phonons, and (ii) markedly improves the sensitivity of the plasmon wavelength on the structural details of the host platform in real space, thus allowing one to use the effect of environmental screening on acoustic plasmons to probe the structure and composition of a van der Waals heterostructure down to the monolayer resolution.
... New information technologies can be generated by OLED displays on flexible and stretchable substrates [9][10][11]. However, the device performances have been limited by the low electrical conductivity and low stability of the organic molecules [12][13][14][15]. ...
Inverted organic light-emitting devices (OLEDs) have been aggressively developed because of their superiorities such as their high stability, low driving voltage, and low drop of brightness in display applications. The injection of electrons is a critical issue in inverted OLEDs because the ITO cathode has an overly high work function in injecting electrons into the emission layer from the cathode. We synthesized hexagonal wurtzite ZnO nanoparticles using different oxidizing agents for an efficient injection of electrons in the inverted OLEDs. Potassium hydroxide (KOH) and tetramethylammonium hydroxide pentahydrate (TMAH) were used as oxidizing agents for synthesizing ZnO nanoparticles. The band gap, surface defects, surface morphology, surface roughness, and electrical resistivity of the nanoparticles were investigated. The inverted devices with phosphorescent molecules were prepared using the synthesized nanoparticles. The inverted devices with ZnO nanoparticles using TMAH exhibited a lower driving voltage, lower leakage current, and higher maximum external quantum efficiency. The devices with TMAH-based ZnO nanoparticles exhibited the maximum external quantum efficiency of 19.1%.
... In metallic nanoparticles (NPs), the light electric field can drive the conduction band electrons into a collective oscillation on the nanoscale, referred to as localized surface plasmon (LSP). 1 Coupling of light to an LSP resonance leads to the local enhancement of the electromagnetic field and to the confinement of the light-matter interaction on the nanoscale, therefore enabling a manifold of applications including surface enhanced spectroscopy, 2 enhanced luminescence, 3 strong-field driven nanoscale currents, 4 enhanced nonlinear optical effects, 5 and strong-coupling quantum optics. 6,7 However, a direct characterization method for the electric fields emerging from the resonantly excited nanostructure is still lacking. ...
The response of metal nanostructures to optical excitation leads to localized surface plasmon (LSP) generation with nanoscale field confinement driving applications in, for example, quantum optics and nanophotonics. Field sampling in the terahertz domain has had a tremendous impact on the ability to trace such collective excitations. Here, we extend such capabilities and introduce direct sampling of LSPs in a more relevant petahertz domain. The method allows to measure the LSP field in arbitrary nanostructures with subcycle precision. We demonstrate the technique for colloidal nanoparticles and compare the results to finite-difference time-domain calculations, which show that the build-up and dephasing of the plasmonic excitation can be resolved. Furthermore, we observe a reshaping of the spectral phase of the few-cycle pulse, and we demonstrate ad-hoc pulse shaping by tailoring the plasmonic sample. The methodology can be extended to single nanosystems and applied in exploring subcycle, attosecond phenomena.
... With the rapid demand of the need for perpetual miniaturization along with low power consumption, light trapping through micro/nanostructures has erupted as the most suitable candidate for attaining high light absorption efficiencies in optoelectronic devices. [1][2][3][4] In lieu of this, vertical nanowires structure exhibits outstanding light-trapping capability owing to its large surface-to-volume ratio, multiple scattering mechanisms taking place within the nanowire array, and photodetector performance based upon variation of core-shell structural parameters as well as the nanotextured pattern deployed over the nanopillar double-shelled layer. ...
The photon‐trapping nanostructures greatly contributes in minimizing the light reflectance losses occurring due to air–semiconductor refractive mismatch in photodetector devices. Here we have proposed a vertically oriented CdSe/CdS/ZnSe tri material‐based multiple core–shell nanopillar array structure to act as a light‐trapping efficient antenna for broadband photodetection applications. The nanopillar structure consist of diamond shaped nanotexturization over its three layer pillar interfaces. The proposed nanotexturization over the triple‐layered nanopillar structure would feature multiple scattering mechanisms for the trapped photons enhancing their optical path length along with the defect‐free confinement of the exciton pairs. The lattice compatibility of the CdS and ZnS shell layers forms a bridge between the lattice‐mismatched CdSe core and ZnSe shell leading towards the attainment of a reduced strain as well as high photochemical stability and photo quantum efficiency. As compared to the single‐layered CdSe/ZnSe nanotextured core–shell nanopillar structure the double‐layered nanotextured CdSe/CdS/ZnSe exhibits a high photoresponsivity of 0.425 A/W and external quantum efficiency of 0.98 is attained. The obtained results exhibit that the double‐shell layered‐based nanotextured nanopillar array structure would be a well‐competent alternative as compared to the planar counterpart for next‐generation photodetector applications.
... IQE can be elevated from 25% to 100% by harnessing triplet e tons through the use of intersystem singlet-to-triplet crossing in phosphorescent emi [28,29]. Despite the high internal quantum efficiency and operational stability of emis iridium or platinum complexes [30][31][32][33], phosphorescent OLEDs (PhOLEDs) encou significant efficiency roll-off due to issues like aggregation-caused quenching and trip triplet and triplet-polaron annihilation [34][35][36][37]. As a result, host-guest systems are c monly employed to disperse phosphorescent emitters into host matrices. ...
... IQE can be elevated from 25% to 100% by harnessing triplet excitons through the use of intersystem singlet-to-triplet crossing in phosphorescent emitters [28,29]. Despite the high internal quantum efficiency and operational stability of emissive iridium or platinum complexes [30][31][32][33], phosphorescent OLEDs (PhOLEDs) encounter significant efficiency rolloff due to issues like aggregation-caused quenching and triplet-triplet and triplet-polaron annihilation [34][35][36][37]. As a result, host-guest systems are commonly employed to disperse phosphorescent emitters into host matrices. ...
Organic light-emitting diodes (OLEDs) have garnered considerable attention in academic and industrial circles due to their potential applications in flat-panel displays and solid-state lighting technologies, leveraging the advantages offered by organic electroactive derivatives over their inorganic counterparts. The thin and flexible design of OLEDs enables the development of innovative lighting solutions, facilitating the creation of customizable and contoured lighting panels. Among the diverse electroactive components employed in the molecular design of OLED materials, the benzophenone core has attracted much attention as a fragment for the synthesis of organic semiconductors. On the other hand, benzophenone also functions as a classical phosphor with high intersystem crossing efficiency. This characteristic makes it a compelling candidate for effective reverse intersystem crossing, with potential in leading to the development of thermally activated delayed fluorescent (TADF) emitters. These emitting materials witnessed a pronounced interest in recent years due to their incorporation in metal-free electroactive frameworks and the capability to convert triplet excitons into emissive singlet excitons through reverse intersystem crossing (RISC), consequently achieving exceptionally high external quantum efficiencies (EQEs). This review article comprehensively overviews the synthetic pathways, thermal characteristics, electrochemical behaviour, and photophysical properties of derivatives based on benzophenone. Furthermore, we explore their applications in OLED devices, both as host materials and emitters, shedding light on the promising opportunities that benzophenone-based compounds present in advancing OLED technology.
... Therefore, phosphorescent OLEDs offer higher efficiencies and thereby more energy-saving display products than fluorescent ones [4]. Reducing the lifetime of triplet excited states (τ) has been proven an effective way to extend the stability of phosphorescent OLEDs [14]. The most important factor at the device level to predominate the device stability is the width of exciton formation zone (W) [15][16][17][18]. ...
... Blue emission is very important to the lighting and flatpanel displays [14,29,30]. Currently, the major hurdle to curb the commercialization of OLEDs is the poor stability of blue phosphorescent OLEDs (B-PHOLEDs). ...
Blue phosphorescent organic light-emitting diodes (B-PHOLEDs) using host–guest emissive layers have been studied, where the host and guest are 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPy) and bis[2-(4,6-difluorophenyl)pyridinato-C²,N](picolinato)iridium(III) (FIrPic), respectively. For the emissive layer with dye (guest) concentration of either 3 mol% or 10 mol%, there exist both the major and minor effective bandgaps. The major effective bandgap is governed by the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) levels of 26DCzPPy, because the host molecules form a major dynamic-favorable channel to transport charge carriers. The minor effective bandgap is governed by the LUMO and HOMO levels of FIrPic, since the guest molecules form a minor thermodynamic-favorable channel to transport charge carriers. For the emissive layer with dye concentration of 22 mol%, the effective bandgap is determined by the LUMO and HOMO levels of FIrPic, because the guest molecules form a both dynamic- and thermodynamic-favorable channel to conduct charge carriers. Although the B-PHOLED with emissive layer of 26DCzPPy:FIrPic (3 mol%) shows wider exciton formation zone than the one with emissive layer of 26DCzPPy:FIrPic (10 mol%), the latter gives higher stability than the former, mostly attributed to the shorter triplet lifetime of 26DCzPPy:FIrPic (10 mol%) than that of 26DCzPPy:FIrPic (3 mol%). Due to both the larger effective bandgap and more charge carrier traps, the emissive layer of 26DCzPPy:FIrPic (10 mol%) enlarges the exciton formation zone and thereby increases device stability than that of 26DCzPPy:FIrPic (22 mol%), despite that the former has the longer triplet lifetime than the latter. The current research provides some novel insights into the correlation of dye-based nanoarchitectonics (dye concentration) with the device performance, helpful for the commercial development of B-PHOLEDs using host–guest emissive layers.
... However, as depicted in Fig. 1a, in a conventional PHOLED, the weak triplet energy transfer to conventional metal-cathode SPPs induces only a modest change in the decay rate, leaving a high triplet density at equilibrium. A promising approach to enhance decay rates was reported by Fusella et al. 24 , who doubled the lifetime of a green PHOLED by means of energy transfer from triplets to SPPs in a thin top metal cathode containing a random array of Ag nanocubes for top-emission extraction. However, this technique introduces complexity that is incompatible with full-colour, stable and scalable displays manufacturing. ...
Phosphorescent organic light-emitting diodes (PHOLEDs) feature high efficiency1,2, brightness and colour tunability suitable for both display and lighting applications³. However, overcoming the short operational lifetime of blue PHOLEDs remains one of the most challenging high-value problems in the field of organic electronics. Their short lifetimes originate from the annihilation of high-energy, long-lived blue triplets that leads to molecular dissociation4–7. The Purcell effect, the enhancement of the radiative decay rate in a microcavity, can reduce the triplet density and, hence, the probability of destructive high-energy triplet–polaron annihilation (TPA)5,6 and triplet–triplet annihilation (TTA) events4,5,7,8. Here we introduce the polariton-enhanced Purcell effect in blue PHOLEDs. We find that plasmon–exciton polaritons⁹ (PEPs) substantially increase the strength of the Purcell effect and achieve an average Purcell factor (PF) of 2.4 ± 0.2 over a 50-nm-thick emission layer (EML) in a blue PHOLED. A 5.3-fold improvement in LT90 (the time for the PHOLED luminance to decay to 90% of its initial value) of a cyan-emitting Ir-complex device is achieved compared with its use in a conventional PHOLED. Shifting the chromaticity coordinates to (0.14, 0.14) and (0.15, 0.20) into the deep blue, the Purcell-enhanced devices achieve 10–14 times improvement over similarly deep-blue PHOLEDs, with one structure reaching the longest Ir-complex device lifetime of LT90 = 140 ± 20 h reported so far10–21. The polariton-enhanced Purcell effect and microcavity engineering provide new possibilities for extending deep-blue PHOLED lifetimes.
... AgNCs greatly enhance the electric field at their sharp corners due to dipole or quadrupole local surface plasmon resonance; this enhancement has been applied to surface-enhanced Raman scattering (SERS), 38,39 photocurrent enhancement for solar cells, 40,41 and spontaneous emission sources. 42,43 In addition, Ag is suitable for surface plasmon excitation at visible wavelengths since it has the lowest absorption losses among all metals. Our previous research has demonstrated mechanical plasmonic color modulation using a self-assembled AgNC monolayer in a stretchable polydimethylsiloxane (PDMS) substrate. ...
We experimentally demonstrated electrical plasmonic color modulation by combining a nematic-phase liquid crystal (LC) layer and a silver nanocube (AgNC) monolayer. The color modulation LC/AgNC device was fabricated by filling LCs with negative dielectric anisotropy onto a densely assembled AgNC monolayer. The transmitted light color through the LC/AgNC device was modulated between green and magenta by applying voltages of 0–15 V. The peaks and dips in the transmission spectrum of the LC/AgNC device at wavelengths of 500–600 nm were switched with voltage. The switching effect of light transmission in the green region was achieved by overlapping the plasmon resonance of the AgNC monolayer and multiple transmittance peaks caused by the birefringence of the LC layer. In addition, the color inversion appeared at cross-Nicole and parallel-Nicole because the LC layer functioned like a half-wave plate due to birefringence. The electrical modulation of the plasmonic color with LCs has a high implementation capability in microdevices and is anticipated to be applied in display devices or color filters.
... This indicates that the dual-microcavity structure reduces triplet density, which can improve device sta-bility by decreasing triplet-triplet annihilation (TTA) and tripletpolaron annihilation (TPA) events. [35] Owing to the same thickness of RGB OLEDs in DMTOLEDs, their electrical characteristics can be maintained. Figure 7 shows the performance of fabricated devices. ...
Microcavity structures are used in inorganic‐, organic‐, quantum‐dot‐, and perovskite‐based electroluminescent (EL) devices to advance next‐generation displays. However, there are difficulties in controlling electrical characteristics and patterning processes for producing different thicknesses for each red, green, and blue (RGB) subpixel, and the issues are more challenging in the high‐resolution display for future realistic media. Here, a novel design method is presented for a dual‐microcavity structure that controls high‐order modes of a second cavity stacked on top of EL devices with the same cavity length for each subpixel to produce multiple peaks at RGB resonant wavelengths. The dual‐microcavity effect demonstrated by top‐emitting organic light‐emitting diodes (OLEDs) can be conveniently fabricated via in situ deposition. By modulating the high‐order modes, the spectral characteristics of each RGB dual‐microcavity top‐emitting OLED (DMTOLED) are manipulated while its electrical properties are maintained. Green DMTOLED exhibits a maximum luminance of 2.075 × 10⁵ cd m⁻², allowing applications not only for commercialized displays but also for outdoor augmented reality and automotive displays. Furthermore, dual‐microcavity structures with narrow spectral bandwidths can be applied to next‐generation EL devices for more realistic media. The method is expected to be applied industrially, promoting the advancement of EL devices for next‐generation displays.
... The strong localization of incident light makes plasmonics ideal for enhancing photoconversion in photovoltaics, 55 PC, 56 and light-emitting devices. 57 2.1.2 | LSPR-induced hot electron-hole pair separation for water splitting Nanostructured plasmonic catalysts are based on hot electron−hole pairs generated by LSPR that are excited by light. ...
Semiconductor‐based solar‐driven water splitting technology is an environmentally friendly and cost‐effective approach for the production of clean fuels. The overall solar‐to‐hydrogen efficiency of semiconductor‐based photo(electro)catalysts is jointly determined by factors, such as light absorption efficiency of the photo(electro)catalysts, internal separation efficiency of charge carriers, and injection efficiency of surface charges. However, the traditional improvement strategies, such as morphology control, functional layer modification, and band alignment engineering, still have certain limitations in enhancing the conversion efficiency of the photo(electro)catalytic water splitting. Recently, unconventional enhancement strategies based on surface plasmonic effects, piezoelectric effects, thermoelectric effects, and magnetic effects have provided unique pathways for improving the solar‐to‐hydrogen efficiency of photo(electro)catalysts. Therefore, this review outlines the fundamental concepts of these physical effects and elucidates their intrinsic mechanisms in enhancing the efficiency of photo(electro)catalysts for water splitting process through practical application examples. Ultimately, the future development of unconventional strategies for enhancing photo(electro)catalytic water splitting is envisioned.
