Fabrication Of Light-emitting Diodes Research Articles

Effect of magnesium doping on NiO hole injection layer in quantum dot light-emitting diodes

Abstract This study reports on the fabrication of quantum dot light-emitting diodes (QLEDs) with an ITO/Ni1−x Mg x O/SAM/TFB/QDs/ZnMgO/Al structure and investigates the effects of various Mg doping concentrations in NiO on device performance. By doping Mg into the inorganic hole-injection layer NiO (Ni1−x Mg x O), we improved the band alignment with the hole-injection layer through band tuning, which enhanced charge balance. Optimal Mg doping ratios, particularly a Ni0.9Mg0.1O composition, have demonstrated superior device functionality, underscoring the need for fine-tuned doping levels. Further enhancements were achieved through surface treatments of Ni0.9Mg0.1O with UV-Ozone (UVO) and thermal annealing (TA) of the ZnMgO electron transport layer. Consequently, by optimizing Mg-doped NiO in QLED devices, we achieved a maximum external quantum efficiency of 8.38 %, a brightness of 66,677 cd/m2, and a current efficiency of 35.31 cd/A, indicating improved performance. The integration of Mg-doped NiO into the QLED structure resulted in a device with superior charge balance and overall performance, which is a promising direction for future QLED display technologies.

Recent Advances in Fluorescent Polyimides.

Polyimide (PI) refers to a type of high-performance polymer containing imide rings in the main chain, which has been widely used in fields of aerospace, microelectronic and photonic devices, gas separation technology, and so on. However, traditional aromatic PIs are, in general, the inefficient fluorescence or even no fluorescence, due to the strong inter- and intramolecular charge transfer (CT) interactions causing unavoidable fluorescence quenching, which greatly restricts their applications as light-emitting functional layers in the fabrication of organic light-emitting diode (OLED) devices. As such, the development of fluorescent PIs with high fluorescence quantum efficiency for their application fields in the OLED is an important research direction in the near future. In this review, we provide a comprehensive overview of fluorescent PIs as well as the methods to improve the fluorescence quantum efficiency of PIs. It is anticipated that this review will serve as a valuable reference and offer guidance for the design and development of fluorescent PIs with high fluorescence quantum efficiency, ultimately fostering further progress in OLED research.

Bidirectional UV/violet heterojunction light-emitting diode with In0.27Al0.73N alloy film as electron transport layer

In this paper, the p-GaN/n-In0.27Al0.73N heterojunction light-emitting diode (LED) was fabricated by radio frequency magnetron sputtering (RF-MS) and the electroluminescence (EL) characteristics of the p-GaN/n-In0.27Al0.73N heterojunction diode was investigated. Based on the preparation of the InXAl1-XN thin films at different substrate temperatures (Ts), the crystal structure, optical and electrical properties were investigated by XRD, SEM and other material characterization techniques. With increasing Ts, the grain size and surface morphology of the InXAl1-XN thin films change dramatically. The film has the best optical and electrical properties when the Ts is 300℃. On the basis of this, the compositional content of indium in the InXAl1-XN film was calculated to be 0.27. The heterojunction LED was fabricated on a commercial p-GaN substrate and the In0.27Al0.73N alloy film. The EL was successfully achieved at various forward and reverse voltages at room temperature and the temperature-dependent EL has been investigated. Furthermore, research is being conducted on the characteristics of the interface of p-GaN/n-In0.27Al0.73N heterojunction and the elucidation of the light-emitting mechanism of diode. The present work uses a simple and low-cost RF-MS method to fabricate UV/Violet bidirectional drive p-GaN/n-In0.27Al0.73N heterojunction LED, which provides a new reference for the fabrication of LED using InXAl1-XN alloy material.

Defects in Nitrogen-Doped ZnO Nanoparticles and Their Effect on Light-Emitting Diodes.

In this study, the effect of defects on the acceptor properties of nitrogen-doped ZnO nanoparticles (NPs) was investigated through the fabrication of light-emitting diodes (LEDs). Nitrogen-doped ZnO NPs were synthesized by an arc discharge in-gas evaporation method and post-annealed at 800 °C in an oxygen and nitrogen atmosphere. The annealed ZnO NPs were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. It was found that the annealing of nitrogen-doped ZnO NPs in a nitrogen environment increased the number of zinc vacancies, while annealing in an oxygen environment increased the number of oxygen vacancies due to nitrogen desorption. The output characteristics of LEDs fabricated with oxygen-annealed NPs were degraded, while those with nitrogen-annealed NPs were significantly improved. From these results, the contribution of zinc vacancies to acceptor formation in ZnO NPs was confirmed for the first time in actual pn junction devices.

Vacuum-Boosting Precise Synthetic Control of Highly Bright Solid-State Carbon Quantum Dots Enables Efficient Light Emitting Diodes.

Carbon quantum dots (C-dots) have emerged as efficient fluorescent materials for solid-state lighting devices. However, it is still a challenge to obtain highly bright solid-state C-dots because of the aggregation caused quenching. Compared to the encapsulation of as-prepared C-dots in matrices, one-step preparation of C-dots/matrix complex is a good method to obtain highly bright solid-state C-dots, which is still quite limited. Here, an efficient and controllable vacuum-boosting gradient heating approach is demonstrated for in situ synthesis of a stable and efficient C-dots/matrix complex. The addition of boric acid strongly bonded with urea, promoting the selectivity of the reaction between citric acid and urea. Benefiting from the high reaction selectivity and spatial-confinement growth of C-dots in porous matrices, in situ synthesize C-dots bonded can synthesized dominantly with a crosslinked octa-cyclic compound, biuret and cyanuric acid (triuret). The obtained C-dots/matrix complex exhibited bright green emission with a quantum yield as high as 90% and excellent thermal and photo stability. As a proof-of-concept, the as-prepared C-dots are used for the fabrication of white light-emitting diodes (LEDs) with a color rendering index of 84 and luminous efficiency of 88.14lm W-1, showing great potential for applications in LEDs.

A Conjugated Carboranyl Main Chain Polymer with Aggregation-Induced Emission in the Near-Infrared.

Materials exhibiting aggregation-induced emission (AIE) are both highly emissive in the solid state and prompt a strongly red-shifted emission and should therefore pose as good candidates toward emerging near-infrared (NIR) applications of organic semiconductors (OSCs). Despite this, very few AIE materials have been reported with significant emissivity past 700 nm. In this work, we elucidate the potential of ortho-carborane as an AIE-active component in the design of NIR-emitting OSCs. By incorporating ortho-carborane in the backbone of a conjugated polymer, a remarkable solid-state photoluminescence quantum yield of 13.4% is achieved, with a photoluminescence maximum of 734 nm. In contrast, the corresponding para and meta isomers exhibited aggregation-caused quenching. The materials are demonstrated for electronic applications through the fabrication of nondoped polymer light-emitting diodes. Devices employing the ortho isomer achieved nearly pure NIR emission, with 86% of emission at wavelengths longer than 700 nm and an electroluminescence maximum at 761 nm, producing a significant light output of 1.37 W sr-1 m-2.

Thermally Induced Phase Separation of the PEDOT:PSS Layer for Highly Efficient Laminated Polymer Light-Emitting Diodes.

Among various conductive polymers, the poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film has been studied as a promising material for use as a transparent electrode and a hole-injecting layer in organic optoelectronic devices. Due to the increasing demand for the low-cost fabrication of organic light-emitting diodes (OLEDs), PEDOT:PSS has been employed as the top electrode by using the coating or lamination method. Herein, a facile method is reported for the fabrication of highly efficient polymer light-emitting diodes (PLEDs) based on a laminated transparent electrode (LTE) consisting of successive PEDOT:PSS and silver-nanowire (AgNW) layers. In particular, thermally induced phase separation (TIPS) of the PEDOT:PSS film is found to depend on the annealing temperature (Tanneal) during preparation of the LTE. At Tanneal close to the glass transition temperature of the PSS chains, a PSS-rich phase with a large number of PSS- molecules enhances the work function of the PEDOT:PSS on the glass-side surface relative to the air side. By using the optimized LTEs, bidirectional laminated PLEDs are obtained with a total external quantum efficiency of 2.9% and a turn-on voltage of 2.6 V, giving a comparable performance to that of the reference bottom-emitting PLED based on a costly evaporated metal electrode. In addition, an analysis of the angular characteristics, including the variation in the electroluminescence spectra and the change in luminance according to the emission angle, indicates that the laminated PLED with the LTE provides a more uniform angular distribution regardless of the direction of emission. Detailed optical and electrical analyses are also performed to evaluate the suitability of LTEs for the low-cost fabrication of efficient PLEDs.

Perfluorooctanoic acid interface modification enabling efficient true-blue perovskite light-emitting diodes and air-processing compatibility

The pure-bromide quasi-2D perovskite has shown advantages in fabrication of blue perovskite light-emitting diodes (PeLEDs) due to its relatively good color stability and capability of moisture resistance. However, the performances of efficiency and luminance of pure-bromide quasi-2D PeLEDs with true-blue (470 nm−480 nm) emission are still inferior. Here, we show a interfacial modification strategy of involving perfluorooctanoic acid (PFOA) to a hole transport layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), to improve the performances of the true-blue PeLEDs. The PFOA regulates the molecular conformation of PEDOT:PSS, forming ordered PEDOT domains that improves the carrier transport and a more favorable band alignment with the perovskite emissive layers. The achieved true-blue PeLEDs show peak EQE of 6.86 % and maximum luminance of 854.10 cd/m2 at wavelength of 478 nm, which are the record values for the pure-bromide quasi-2D PeLEDs in true-blue region. Moreover, owing to the hydrophobic fluorine-carbon (C-F) chains of PFOA, we successfully fabricate the blue PeLEDs in air condition without inert gas protection. This work paves the way for commercial applications in next-generation display technologies.

Direct Evidence of the Effect of Water Molecules Position in the Spectroscopy, Dynamics, and Lighting Performance of an Eco-Friendly Mn-Based Organic-Inorganic Metal Halide Material for High-Performance LEDs and Solvent Vapor Sensing.

Luminescent Mn(II)-based organic-inorganic hybrid halides have drawn attention as potential materials for sensing and photonics applications. Here, the synthesis and characterization of methylammonium (MA) manganese bromide ((MA)nBrxMn(H2O)2, (n = 1, 4 and x = 3, 6)) with different stoichiometries of the organic cation and inorganic counterpart, are reported. While the Mn2+ centers have an octahedral conformation, the two coordinating water molecules are found either in cis (1) or in trans (2) positions. The photophysical behavior of 1 reflects the luminescence of Mn2+ in an octahedral environment. Although Mn2+ in 2 also has octahedral coordination, at room temperature dual emission bands at ≈530 and ≈660nm are observed, explained in terms of emission from Mn2+in tetragonally compressed octahedra and self-trapped excitons (STEs), respectively. Above the room temperature, 2 shows quasi-tetrahedral behavior with intense green emission, while at temperatures below 140K, another STE band emerges at 570nm. Time-resolved experiments (77-360K) provide a clear picture of the excited dynamics. 2 shows rising components due to STEs formation equilibrated at room temperature with their precursors. Finally, the potential of these materials for the fabrication of color-tunable down-converted light-emitting diode (LED) and for detecting polar solvent vapors is shown.

B‒N covalent bond-involved π-extension of multiple resonance emitters enables high-performance narrowband electroluminescence.

Multi-boron-embedded multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters show promise for achieving both high color-purity emission and high exciton utilization efficiency. However, their development is often impeded by a limited synthetic scope and excessive molecular weights, which challenge material acquisition and organic light-emitting diode (OLED) fabrication by vacuum deposition. Herein, we put forward a B‒N covalent bond-involved π-extension strategy via post-functionalization of MR frameworks, leading to the generation of high-order B/N-based motifs. The structurally and electronically extended π-system not only enhances molecular rigidity to narrow emission linewidth but also promotes reverse intersystem crossing to mitigate efficiency roll-off. As illustrated examples, ultra-narrowband sky-blue emitters (full-width at half-maximum as small as 8nm in n-hexane) have been developed with multi-dimensional improvement in photophysical properties compared to their precursor emitters, which enables narrowband OLEDs with external quantum efficiencies (EQEmax) of up to 42.6%, in company with alleviated efficiency decline at high brightness, representing the best efficiency reported for single-host OLEDs. The success of these emitters highlights the effectiveness of our molecular design strategy for advanced MR-TADF emitters and confirms their extensive potential in high-performance optoelectronic devices.

High-brightness thermally evaporated perovskite light-emitting diodes via dual-interface engineering

Thermal evaporation emerges as a promising method for the scale-up fabrication of perovskite light-emitting diodes (PeLEDs) due to its superior repeatability and compatibility with the existing display industry compared to conventional solution process. However, the brightness of current high-efficiency thermally evaporated PeLEDs is generally constrained to a range of thousands of cd/m2. Herein, we propose a dual-interface engineering strategy to modulate the charge injection properties and passivate surface defects in the co-evaporated Cs–Pb–Br perovskite emitter. Our findings demonstrate that introducing 4,4′-Cyclohexylidenebis [N, N-bis(4-methylphenyl) benzenamine] additive to the bottom hole transport layer poly (9-vinylcarbazole) not only facilitates hole injection but also increases the conductivity. Meanwhile, the deposition of functionalized phenylethylammonium bromide salts with a specific number of fluorine atoms passivates the top surface defects and enhances the charge transport simultaneously. Consequently, the optimal PeLEDs achieve a maximum luminance of 75,012 cd/m2, marking one of the brightest thermally evaporated PeLEDs reported to date. The proposed strategy holds significant potential to guide the preparation of high-performance thermally evaporated PeLEDs for high-radiance display applications.

Inkjet-printed multilayer structure for low-cost and efficient OLEDs

Inkjet printing is considered a key technology in the fabrication of organic light-emitting diodes (OLEDs), but achieving a fully inkjet-printable OLED structure is still a challenge. Here, we propose the fabrication of OLEDs with an inkjet-printed multilayer structure (i.e. anode/hole injection layer (HIL)/electron blocking layer (EBL)/emitting layer (EML)) by properly developing new HIL and EBL inks to achieve uniform and homogeneous printed thin films. In the fabricated multilayer device, the dissolution process of the EBL, which occurs during the printing of the EML, creates a blurred interface, resulting in device performance that achieves maximum current efficiencies of 20 cd/A and 7 cd/A with ITO and printed polymeric anode, respectively. With the aim of simplifying the structure of the device and mimicking the formation of such a blurred interface, another printed multilayer structure (i.e. anode/printed HIL/printed EBL:EML) was proposed, achieving maximum current efficiencies of 13 and 6 cd/A with ITO and polymeric anode, respectively. Such results represent a compromise between simplifying the fabrication process and achieving good electro-optical properties and thus represent a further step towards the fabrication of a fully inkjet-printed ITO-free OLED.

Structural Engineering of Iridium(III) Phosphors with Imidazo[4,5-b]pyrazin-2-ylidene Cyclometalates for Efficient Blue Electroluminescence.

Iridium(III) complexes are particularly noted for their excellent potentials in fabrication of blue organic light-emitting diodes (OLEDs), but the severe efficiency roll-off largely hampered their practical applications. To reveal the underlying characteristics, three Ir(III) complexes, namely f-ct5c, f-ct5d, and f-ct11, bearing imidazo[4,5-b]pyrazin-2-ylidene cyclometalates are prepared and characterized in detail. Both f-ct5c and f-ct5d (also their mixture f-ct5mix) gave intensive blue emissions peaking at ≈465nm with short radiative lifetimes of 1.76 and 2.45µs respectively, in degassed toluene. Alternatively, f-ct11 with two 4-tert-butylphenyl substituents on each imidazo[4,5-b]pyrazin-2-ylidene entity, possessed a bluish-green emission (508nm) together with an extended radiative lifetime of 34.3µs in the dispersed PMMA matrix. Consequently, the resulting solution-processed OLED with f-ct11 delivered a maximum external quantum efficiency (EQEmax ) of 6.5% with serious efficiency roll-offs. In contrast, f-ct5mix based device achieved a high EQEmax of 27.2% and the EQE maintained at 23.0% of 1000cdm-2 . Furthermore, the hyper-OLEDs with f-ct5mix as the sensitizer and v-DABNA as the terminal emitter afford narrowed emission with a considerably high EQEmax exceeding 32%, affirming the potential of f-ct5mix to serve as both the emitter and sensitizer in OLEDs.

Electroluminescence efficiency and stability of near ultraviolet organic light-emitting diodes based on BCPO luminous materials

To date, in the traditional method of obtaining near-ultraviolet (NUV) light, mercury atoms, which can create a highly toxic heavy metal contaminant, have been used. Therefore, it is an important issue to obtain NUV light by using new environmentally friendly devices. In the last decade, the fabrication of near ultraviolet organic light-emitting diodes (NUV-OLEDs) has become a research hotspot in the field of organic electronics. However, when the electroluminescence wavelength is extended to shorter than 400 nm, higher requirements are put forward for the materials used for each functional layer in these devices. In this work, a wide bandgap small molecule material of BCPO is used as the luminescent layer. The electron-transporting and hole-transporting materials are determined based on the overlaps between absorption spectra of these materials and emission spectrum of BCPO. And NUV-OLEDs with electroluminescent peak wavelength at 384 nm are prepared. By using the optimal device structure, the maximum external quantum efficiency of the device reaches 2.98%, and the maximum radiance of the device reaches 38.2 mW/cm<sup>2</sup>. In the electroluminescence spectrum, NUV light with wavelengths below 400 nm accounts for 57% of the light emission. In addition, the device demonstrates good stability when biased at two different constant voltage modes. The multiple key factors which affect the stability of the device are analyzed in detail. Firstly, it is found that the high glass transition temperature (<i>T</i><sub>g</sub>) of hole-transporting material is very important for the long-time stability of this device. The poor device stability is closely related to the low <i>T</i><sub>g</sub> temperature of hole-transporting material. Secondly, due to the widespread use of PEDOT:PSS as hole injection material in OLEDs, the electron leakage from the hole-transpor layer into the PEDOT:PSS layer may cause significant damage to the conducting polymer. When bombarded with low energy electrons, bond breakage occurs on the surface of PEDOT:PSS, followed by the release of oxygen and sulfur, resulting in changes in conductivity and oxidation reactions with molecules of hole transport material. Thirdly, the photoelectrical stability of organic molecules is the most fundamental reason that restricts the device lifetime. The aging process of material or device is directly relevant to the bond dissociation energy (BDE) of organic molecule. Generally, the BDE value of organic molecule is not high enough. As a result, molecules are prone to chemical bond breakage during electrochemical or photochemical aging. In summary, highly stable NUV-OLEDs should be fabricated by using hole-transporting materials with high <i>T</i><sub>g</sub> temperature, sufficient electron-blocking capacity, and large BDE value.

Structural, optical and photoluminescence properties of BaLa2ZnO5: Eu3+ phosphor: A prospective red-emitting phosphor for LED applications

Herein, we report the synthesis of red-emitting Eu3+-activated BaLa2ZnO5 phosphors using a high-temperature solid-state reaction technique. The phase confirmation and crystal structure were established through X-ray powder diffraction patterns. Density-functional theory calculations revealed an indirect bandgap in the material. The bandgaps of both undoped and doped BaLa2ZnO5 phosphors were analyzed using diffuse reflectance spectra. The influence of Eu3+ doping on the bandgap was confirmed by applying the Kubelka-Munk function to the diffuse reflectance spectra. The effects of doping on the surface morphology and elemental composition were investigated through field emission scanning electron microscopy and energy-dispersive spectroscopy, respectively. Additionally, X-ray photoelectron spectroscopic studies were conducted to analyze the electronic structure, chemical states and impact of doping on the crystal structure. Using near ultraviolet excitation at 329 nm, the synthesized phosphor exhibited strong red emission attributed to various 5D0 → 7FJ transitions. Concentration quenching phenomena were observed due to dipole-dipole interactions. Judd-Ofelt analysis was performed to elucidate the coordination nature of the doping element in the host lattice. Excellent thermal stability was observed with an activation energy of 0.64 eV for discharging via lattice vibrations. The better color purity (98–99.3 %) and stable Commission Internationale de l’Elcairage coordinates in the red region of the gamut suggest that the prepared phosphor material holds potential as an efficient candidate for ultra violet and blue light-emitting diode chips, as well as an efficient component in the fabrication of white light-emitting diodes.

Structural and Material-Based Approaches for the Fabrication of Stretchable Light-Emitting Diodes.

Stretchable displays, capable of freely transforming their shapes, have received significant attention as alternatives to conventional rigid displays, and they are anticipated to provide new opportunities in various human-friendly electronics applications. As a core component of stretchable displays, high-performance stretchable light-emitting diodes (LEDs) have recently emerged. The approaches to fabricate stretchable LEDs are broadly categorized into two groups, namely "structural" and "material-based" approaches, based on the mechanisms to tolerate strain. While structural approaches rely on specially designed geometries to dissipate applied strain, material-based approaches mainly focus on replacing conventional rigid components of LEDs to soft and stretchable materials. Here, we review the latest studies on the fabrication of stretchable LEDs, which is accomplished through these distinctive strategies. First, we introduce representative device designs for efficient strain distribution, encompassing island-bridge structures, wavy buckling, and kirigami-/origami-based structures. For the material-based approaches, we discuss the latest studies for intrinsically stretchable (is-) electronic/optoelectronic materials, including the formation of conductive nanocomposite and polymeric blending with various additives. The review also provides examples of is-LEDs, focusing on their luminous performance and stretchability. We conclude this review with a brief outlook on future technologies.

Defect Engineering of Metal Halide Perovskite Nanocrystals via Spontaneous Diffusion of Ag Nanocrystals.

Perovskite nanocrystals (NCs) have emerged as a promising building block for the fabrication of optic-/optoelectronic-/electronic devices owing to their superior characteristics, such as high absorption coefficient, rapid ion mobilities, and tunable energy levels. However, their low structural stability and poor surface passivation have restricted their application to next-generation devices. Herein, a drug delivery system (DDS)-inspired post-treatment strategy is reported for improving their structural stability by doping of Ag into CsPbBr3 (CPB) perovskite NCs; delivery to damaged sites can promote their structural recovery slowly and uniformly, averting the permanent loss of their intrinsic characteristics. Ag NCs are designed through surface-chemistry tuning and structural engineering to enable their circulation in CPB NC dispersions, followed by their delivery to the CPB NC surface, defect-site recovery, and defect prevention. The perovskite-structure healing process through the DDS-type process (with Ag NCs as the drug) is analyzed by a combination of theoretical calculations (with density functional theory) and experimental analyses. The proposed DDS-inspired healing strategy significantly enhances the optical properties and stability of perovskite NCs, enabling the fabrication of white light-emitting diodes.

Flexible Perovskite Light‐Emitting Diodes: Characteristics and Performance

AbstractFuture displays need to be stretchable, bendable, and wearable to match consumers’ needs for convenience, portable equipment, and real‐time information display. The development of flexible light source components, like flexible light‐emitting diodes (LEDs), is urgently required to fulfill these needs. Metal halide perovskites, known for their excellent optoelectronic properties and ductility, are considered the most promising light‐emitting materials for high‐definition displays, and their outstanding advantage is that the metal halide perovskites would be achieved by solution process under low temperature (<150 °C), which is especially good for the flexible organic substrates to maintain high conductivity during fabrication of flexible LEDs. In recent years, flexible perovskite LEDs have made significant progress, but still face a great deal of difficulties, obstacles, and great challenges. Herein, the mechanical properties of perovskite materials are examined and the failures for perovskite‐based flexible optoelectronic devices under strain are discussed. The authors then focus on optimizing each functional layer and the recent advancement in flexible perovskite LEDs is summarized. Finally, a brief outlook on the challenges faced by flexible perovskite LEDs and their possible future development is provided.

Dual emission quaternary alloyed quantum dots for white light-emitting diodes with high color-rendering index

We report the synthesis of manganese doped Ag–Zn–In–S(AZIS)/ZnS QDs for the facile fabrication of white light-emitting diodes (WLEDs). By controlling the ratio of Mn/(Zn + In), dual emission Mn:AZIS/ZnS QDs with different relative proportion of host emission and Mn2+-related emission were prepared. With proper doping, the emission of Mn: AZIS/ZnS QDs covers most of the visible spectrum. Based on the as prepared Mn:AZIS/ZnS QDs, a warm WLED device exhibited a highest color rendering index (CRI) of 92.5 companied by a correlated color temperature (CCT) of 3162 K. With the increasing of Mn2+ concentration, the corresponding WLED devices shown warmer CCT values and lower luminous efficiencies (LEs). The color-conversion efficiency of the QDs decreasing with the increasing of Mn2+ concentration may be responsible partly for the variation of device LEs. With further deep investigation on the mechanism of color-conversion between the exciting light and QDs, and the energy transfer from the host material to the manganese dopant, WLEDs based on the dual emission Mn:AZIS/ZnS QDs with better device performances are excepted to find diverse application in lighting fields.

Influence of gold nanostructures on excited state intramolecular proton transfer in multidomain HTTH dye

Organic multidomain dyes exhibiting excited state intramolecular proton transfer (ESIPT) are known due to large Stokes shifts and dependence of their luminescence spectral characteristics on the properties of the environment. In this work, influence of gold nanostructures on the spectral characteristics of a “polycarbonate matrix – gold nanostructures – HTTH” system was studied using thiazole dye HTTH as an example. A hypothesis about the possibility of plasmon resonance energy transfer (PRET) between the HTTH molecules in different states, namely the ground state (enol form) and the state after proton transfer (keto form), mediated by gold nanostructures was experimentally tested. Presence of gold nanostructures in the vicinity of HTTH molecules was found to lead to the changes in the ratio of the luminescence peak intensities for the enol and keto form of these molecules. This phenomenon opens up the possibility of additional regulation of the spectral characteristics and may evidence the PRET effect in the systems containing ESIPT-exhibiting dyes and plasmonic nanostructures. The obtained results improve our understanding of the physical processes in the systems similar to the studied one and imply new practical applications of them such as fabrication of organic light-emitting diodes, sensors, super-resolution microscopy tools and ultraviolet-to-visible radiation convertors.