Emissive Layer Research Articles

Electroluminescent and photoluminescent light-emitting diodes from carbon dots and device architecture optimization.

Light emission from carbon dots (CDs) is of great interest in both electroluminescence and photoluminescence. Herein, we construct electroluminescent and photoluminescent light-emitting diodes (LEDs) from emitters of CDs. The electroluminescent LED with host-guest-doped dual emissive layers (EMLs) of [poly(9-vinylcarbazole) (PVK)-CDs] × 2 gives satisfactory electro-optical properties, with maximum luminance of 560 cd m-2 at 16 V, luminous efficiency of 0.183 cd A-1, power efficiency of 0.082 lm W-1, and external quantum efficiency of 0.25%, which are superior to the counterparts with single-EML of CDs, single-EML of [PVK-CDs], and triple-EMLs of [PVK-CDs] × 3. These enhanced properties are rationally ascribed to optimization of the device architecture, carrier balance improvement, and reduction in concentration-induced quenching. The electroluminescent LEDs also show color evolution from PVK to CDs, and/or to the PVK/CDs interface, with increasing driving voltages, owing to incomplete energy transfer from PVK to CDs. Highly efficient photoluminescent LEDs with 365- and 395-nm UV excitation are demonstrated. With a CDs : polyvinyl pyrrolidone ratio of 1 : 3, the 365-nm excited photoluminescent LED gives a maximum luminance of 512 347 cd m-2 with a power efficiency of 25.2 lm W-1, while the 395-nm excited photoluminescent device gives a maximum luminance of 670 954 cd m-2 with a power efficiency of 22.0 lm W-1, with both showing yellow emission. Our experiments provide some new ideas for broadening CD applications and advancing LEDs.

Organic Light-Emitting Diodes Comprising an Undoped Thermally Activated Delayed Fluorescence Emissive Layer and a Thick Inorganic Perovskite Hole Transport Layer

Organic Light-Emitting Diodes Comprising an Undoped Thermally Activated Delayed Fluorescence Emissive Layer and a Thick Inorganic Perovskite Hole Transport Layer

Pure white emission full thermally activated delayed fluorescence organic light emitting diode with a supplementary emission layer

In addition to efficiency and lifetime, spectral stability, high color rendering index (CRI), and the Commission Internationale de l’Eclairag (CIE) coordinate close to the equi-energy white point (0.33, 0.33) are also important parameters for the development of white organic light emitting diodes (WOLEDs). However, how to realize these advantages at the same time is a challenge. In this paper, a series of white devices based on complementary color full thermally activated delayed fluorescence (full-TADF) emitters were fabricated with the aim to obtain WOLEDs with high color rendering index and CIE coordinate near the equi-energy white point. Through optimizing the doping concentration of the emitters, adding a supplementary emission layer, modifying the thickness of the main emission layer and the supplementary emission layer, the best device displays the CIE coordinates of (0.34, 0.35) and the CRI of 86, exhibiting good white emission. The results in this paper may provide a feasible method for realizing complementary color full-TADF WOLEDs with pure white emission.

Host Engineering of Deep‐Blue‐Fluorescent Organic Light‐Emitting Diodes with High Operational Stability and Narrowband Emission

AbstractThe realization of highly operationally stable blue organic light‐emitting diodes (OLEDs) is a challenge in both academia and industry. This paper describes the development of anthracene–dibenzofuran host materials, 2‐(10‐(naphthalen‐1‐yl)anthracen‐9‐yl)naphtho[2,3‐b]benzofuran (Host 1) and 2‐(10‐([1,1′‐biphenyl]‐2‐yl)anthracen‐9‐yl)naphtho[2,3‐b]benzofuran (Host 2), namely for use in the emissive layer of an OLED stack. A multiple‐resonance thermally activated delayed serves as the blue fluorescence emitter and exhibits an initial luminance of 1000 cd m−2 and long operational stability (i.e., time to decay to 90% of initial luminance) of 249 h. Furthermore, a deep‐blue OLED with an optimized top‐emitting architecture with a high current efficiency of 154.3 cd A−1, is fabricated and calibrated to a Commission International de l’Éclairage y chromaticity coordinate of 0.048. Moreover, the emission spectrum of this OLED has a narrowband peak at 476 nm with a full width at half maximum (FWHM) of 16 nm. This work provides valuable insights into the design of anthracene‐based host materials and highlights the importance of host optimization in improving the operational stability of OLEDs.

Deep blue high-efficiency solution-processed triplet-triplet annihilation organic light-emitting diodes using bis(8-carbazol-N-yl)fluorene- and benzonitrile-modified anthracene/chrysene fluorescent emitters

Triplet-triplet annihilation (TTA) emitters can effectively utilize non-radiative triplet excitons through the interaction of low triplet energy excitons to produce high energy singlet excitons, but they are mostly restricted by their multilayered device structure fabricated using layer-by-layer thermal vacuum evaporation. It is a great challenge to develop, for the first time, efficient solution-processed non-doped TTA organic light-emitting diodes (OLEDs). In this study, two solution-processable blue emissive TTA molecules (FAnCN and FCsCN) bearing (anthracen-9-yl)benzonitrile (AnCN) and (chrysen-6-yl)benzonitrile (CsCN) as TTA emissive cores modified with 9,9′-bis(8-(carbazole-N-yl)octyl)fluorene (F) are designed and synthesized, respectively. The experimental and theoretical studies reveal that both molecules exhibit deep blue emissions, amorphous morphology with good thermal stability, high-quality solution-cast thin films, decent hole mobility, high-lying HOMO levels (∼-5.45 eV), and suitable lowest singlet (S1)/triplet (T1) excited states (2T1 > S1) for TTA process. FAnCN and FCsCN are successfully employed as solution-processed non-doped emissive layers (EML) in simple structured TTA OLEDs. These devices show intense blue emissions, low turn-on voltages (∼3.6 V), excellent electroluminescent (EL) performances (EQEmax = 5.47–6.84 % and LEmax = 5.66–5.83 cd/A), and TTA characteristics. Especially, FCsCN-based TTA OLED emits deep blue EL emission peaked at 435 nm with a high EQEmax of 6.84 %. This work not only presents a new strategic design for the preparation of solution-processable TTA emitter, but also further ratifies that the TTA mechanism can also be applicable in solution-processed OLEDs.

High Efficiency Non‐Doped Organic Light Emitting Diodes Based on Pure Organic Room Temperature Phosphorescence by High‐Lying Singlet Exciton Fission

AbstractHeavy‐metal‐free pure organic room temperature phosphorescence (ORTP) holds great potential in the field of organic optoelectronic devices owing to low economic cost, simple preparation techniques, and high exciton utilization. However, it is still filled with challenges in realizing high efficiency organic light‐emitting diodes (OLEDs) and exploring the internal physical mechanism based on these ORTP molecules. Here, a high‐performance OLED induced by an unexpected interfacial spin‐mixing process between the ORTP molecule and interlayers is demonstrated, and the high efficiency electroluminescence (EL) mechanism is studied through magneto–electroluminescence (MEL) and magneto–photoluminescence (MPL) measurements. The steady‐state and transient PL properties imply that the interfacial effect is related to a high‐lying singlet fission (HLSF) process in the ORTP molecule itself. Further, the HLSF process and the corresponding energy level position are confirmed by the incident wavelength‐ and temperature‐dependent PL spectra and the magnetic‐field‐dependent transient PL. Finally, by optimizing the interfacial material adjacent to the emissive layer to utilize this interfacial spin mixing effect, a high‐efficiency non‐doped ORTP‐OLED with external quantum efficiency of 16% and CIE coordinates of (0.27, 0.49) is developed. The proposed mechanism during the EL process will give insight to produce more efficient OLEDs based on ORTP materials in the future.

Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Precision graphene nanoribbons (GNRs) offer distinctive physicochemical properties that are highly dependent on their geometric topologies, thereby holding great potential for applications in carbon-based optoelectronics and spintronics. While the edge structure and width control has been a popular strategy for engineering the optoelectronic properties of GNRs, non-hexagonal-ring-containing GNRs remain underexplored due to synthetic challenges, despite offering an equally high potential for tailored properties. Herein, we report the synthesis of a wavy GNR (wGNR) embedding periodic eight-membered rings into its carbon skeleton, which is achieved by the A2B2-type Diels-Alder polymerization between dibenzocyclooctadiyne (6) and dicyclopenta[e,l]pyrene-5,11-dione derivative (8), followed by a selective Scholl reaction of the obtained ladder-type polymer (LTP) precursor. The obtained wGNR, with a length of up to 30 nm, is thoroughly characterized by solid-state NMR, FT-IR, Raman, and UV-Vis spectroscopy with the support of DFT calculations. The non-planar geometry of wGNR efficiently prevents the inter-ribbon π-π aggregation, leading to photoluminescence in solution. Consequently, the wGNR can function as an emissive layer for organic light-emitting electrochemical cells (OLECs), offering a proof-of-concept exploration in implementing luminescent GNRs into optoelectronic devices. The fast-responding OLECs employing wGNR will pave the way for advancements in OLEC technology and other optoelectronic devices.

Enhancing device characteristics of InP quantum dot LED through structural modification with polyethylene glycol blend

This study explored the integration of polyethylene glycol (PEG) into InP-based quantum dot (QD) light-emitting diodes (LEDs). By 5 wt% of PEG 400 blended into the QD emission layer (EML), we achieved an enhancement in both current efficiency (100 %) and external quantum efficiency (91 %). X-ray reflectivity revealed significant morphological changes in the QD EML upon PEG incorporation, primarily manifesting as increased thickness in the dense surface region without affecting the total thickness. This adjustment influenced electron density distribution, impacting hole and electron flow. Overall, the addition of PEG not only improved the electrical properties of QD LEDs but also reshaped the internal morphology of the QD EML. Notably, the efficiency improvements observed rival those achieved by integrating traditional hole transport materials into QD EMLs.

Atom layer deposited TiO2 electron transport layer for silicon heterojunction solar cells to achieve high performance

Silicon/compound heterojunction (SCH) solar cells based on p-type and n-type c-Si wafers using atom layer deposition-TiO2 and low work function metal as the electron transport layer and rear electrode are fabricated. Efficiencies of 20.6 % and 21.6 % are achieved on p-type and n-type silicon solar cells, respectively. High Voc exceeding 700 mV have been realized on both kinds of Si wafers. Special attention has been paid to the SCH solar cells based on p-type c-Si wafers in which the TiO2 electron transport layer serves as the emitter. Carrier transport mechanisms and junction characteristics of the SCH solar cells are analyzed based on dark J-V measurement. The formation of a strong inversion layer at the Si surface region is determined, which implies the high Voc potential of the SCH solar cells based on p-type Si. An optical loss analysis is performed along with a possible solution to further improve the Jsc. The feasibility of TiO2 applied as an efficient electron transport layer (emitter) in p-type SCH solar cells with high performance has been showed.

Enhancing Reliability and Regeneration of Single Passivated Emitter Rear Contact Solar Cell Modules through Alternating Current Power Application to Mitigate Light and Elevated Temperature‐Induced Degradation

The study explores a novel method to combat the Light and Elevated Temperature‐Induced Degradation (LeTID) in solar cell modules, which significantly reduces their efficiency and lifespan. This method involves applying alternating current (AC) of various waveforms (triangular, sinusoidal, and square) and frequencies (5 and 100 kHz) to boron‐doped p‐type passivated emitter rear contact (p‐PERC) solar cell modules. This approach effectively lowers the series resistance at the critical junction between the silver (Ag) contact and the silicon emitter layer of the PERC solar cell, thereby reducing charge recombination hindered by high resistance, especially at elevated temperatures. As a result, there is an improved flow of electrical charges, leading to decreased energy loss and increased solar cell efficiency. The study's findings indicate that a slow, smooth sinusoidal AC waveform at 100 kHz is particularly effective, restoring about 100% of the original performance of the panel. Moreover, oscillations at 5 kHz also show considerable efficacy, recovering more than 96% of the performance. The sinusoidal waveform is noted to surpass both triangular and square waveforms in recovery efficiency. This research highlights the use of high‐frequency AC electricity as a viable strategy to extend the lifespan and enhance the performance of solar panels.

High‐Efficiency Deep Red Fluorescent Material with Aggregation Induced Emission and the Application in Organic Light‐Emitting Diodes

AbstractThe development of highly efficient deep red materials with emission wavelength beyond 650 nm remains a big challenge due to the constraints imposed by the energy gap rule. In this work, a donor‐acceptor‐donor type emitter, 4,7‐bis (10‐(4‐(tert‐butyl) phenyl)‐10H‐phenothiazin‐3‐yl) benzo[c][1,2,5] thiadiazole (TBPPTZ) is designed and synthesized. Resulting from the slight twist angle between the donor and acceptor units, TBPPTZ exhibits nearly planar conformation and an extended conjugated structure. TBPPTZ shows a deep red emission peak at 687 nm and aggregation induced emission property with a high photoluminescence quantum yield of 45 % in neat thin film. The optimized organic light‐emitting diode (OLEDs) utilizing TBPPTZ as the non‐doped emissive layer obtains a high external quantum efficiency (EQE) up to 2.51 % with an electroluminescence (EL) peak at 676 nm, aligning with the Commission Internationale de L'Eclairage (CIE) coordinates (0.68, 0.31), which shows a small EQE roll‐off of only 5.6 % at 100 cd m−2. Additionally, the doped OLED achieves an EQE up to 5.09 %, with an EL peak at 656 nm and CIE coordinates of (0.65, 0.34). The findings of this research not only contribute to achieve highly efficient deep red OLEDs but also offer a novel and effective deep red molecular strategy to realize high‐quality OLEDs.

Полевая электронная спектроскопия молекулярно-напыленного оксидного термокатода

The results of a study of the emission characteristics of a molecular-sprayed oxide thermocathode based on triple carbonate of alkaline earth metals with an emission layer thickness of ~1 µm in the operating temperature range of 590-730 °C. are presented. The results are in good agreement with those obtained earlier for a serial oxide thermocathode with an emission layer thickness of ~100 µm applied by pulverization, and correspond to the model of a "spotted cathode" - a superposition of emission spots at different stages of activation. An idea of the activation phenomenon occurring at a given temperature in a certain range of values of the electric field strength on the surface of emission spots is detailed both with an increase and a decrease in the anode voltage. The energy spectra of the emitted electrons of a separate emission spot with a half-height width of ~100 meV have been obtained. The values of the potential change of the emitting surface of the cathode within the probed region of 0.9 V and the potential drop on the emission layer under the probed region of 4.1 V were measured.

Enhancing the operational stability of OLED devices through the utilization of deuterated TTU host materials

Recent research on anthracene-based hydrocarbon (PNA) as the emissive layer host found that deuteration mediated the formation of these adduct species, presumably quenchers, and thus improved the device lifetime. Meanwhile, studies on deuterium in PNA host materials with stepwise deuteration are scarce. In this work, we report a systematic study of isotopic effects through independent deuteration of the phenyl or/and the dibenzofuran unit on a series of PNA materials polyaromatic dibenzofuran (PAF, PAF-d5, PAF-d7 and PAF-d12). We fabricated fluorescent OLED based on this triplet-triplet up-conversion active host materials for conventional MR-TADF emitter. A short-lived excited delayed lifetime of less than 2 μs has been observed in their electroluminescence decay studies. In addition, LT80 of up to 12.7 h has been observed in PAF-d12 at the brightness of 1000 cd m−2, corresponding to a 4-fold enhancement of OLED stability compared to the non-deuterated counterpart. We hope the current research can provide insights for further device improvement.

High‐Efficiency Hybrid White Organic Light‐Emitting Diodes with Extremely Low Efficiency Roll‐Off and Superior Color Stability Enabled by an Emitting System with Imidazole‐Biphenyl Derivatives

AbstractHybride white organic light‐emitting diodes (WOLEDs) have experienced great success as a prospective technology for the new generation lighting source. Nevertheless, WOLEDs exhibiting excellent effciency and good color stability at high operation brightness are still rare. Herein, a simple but efficient blue molecule, pyrenoimidazole‐biphenyl (PPyIM), which exhibits promising external quantum efficiency (EQE) of 7.6% and 7.2% at the luminescence of 1000 −and 5000 cd m−2 in nondoped blue OLED, is first developed. And then, phenanthroimidazole‐biphenyl (PPIM) with analogous molecular skeleton of PPyIM is chosen as the host of phosphorescent dye PO‐01, and the resulting doped device achieves excellent EQE of 26.5% at the high luminescence of 5000 cd m−2. Furthermore, adopting PPyIM as nondoped blue emissive layer, the two‐color hybrid WOLED exhibites stable warm white emission with CIE coordinates of (0.454, 0.439), color rendering index (CRI) of 45, and correlated color temperature (CCT) of 2996 K. The maximum EQE reaches 23.5%, and the EQE still maintains 21.2% even at the luminance of 5000 cd m−2. Notably, this device exhibits exceptionally stable warm white emission, the CIE coordinates variation is only (0.004, 0.003) in the wide luminance range from 400 to 10000 cd m−2, representing the best outcome for hybrid WOLEDs to date.

Enhanced performance of ambient-air processed CsPbBr3 perovskite light-emitting electrochemical cells via synergistic incorporation of dual additives

Metal halide perovskite light-emitting electrochemical cells (MHP-LECs) are promising due to their facile solution processability and exceptional optoelectrical properties. However, commercialization is hindered by poor thin-film coverage and the need for glovebox processing. This study addresses these issues by incorporating poly(ethylene oxide) (PEO) and potassium hexafluorophosphate (KPF6) into cesium lead bromide perovskite (CsPbBr3) emitting layers (EML), processed under ambient-air conditions. These perovskite composite thin films were spin-coated on a preheated substrate, and the device structure was ITO/PEDOT:PSS/EML/Al. Notably, the MHP-LEC based on CsPbBr3:PEO:KPF6 (100:65:0.2, weight ratio) exhibited pure-green emission with a peak at 524 nm and a narrow full width at half-maximum of 27 nm. Compared to a reference device (CsPbBr3:PEO (100:65, weight ratio)), the new device showed 1.5-, 4-, and 5-fold improvements in current density, electroluminescence (EL) intensity, and lifetime, respectively. These enhancements are attributed to reduced non-radiative current leakage, improved film surface coverage and passivation, and balanced charge carrier injection and transportation. This study offers a straightforward approach for processing CsPbBr3 thin films under ambient-air conditions, enhancing the EL performance of MHP-LECs.

Tailoring the luminescent and structural behaviors of pH-driven PPy/gC3N4/ZrO2 nanocomposite as an emissive layer material for OLED application

The polymeric nanocomposites were synthesized via an in-situ polymerization method, optimized through pH adjustment of zirconium oxide rather than concentration variation. X-ray powder diffraction analysis revealed phase transitions and average crystallite sizes ranging from approximately 6.52–9.16 nm, depending on the pH levels. Field Emission Scanning Electron Microscopy tool is used to analyze the granular nanosheets and nanoparticles like the microstructure of polypyrrole, graphitic carbon nitride and zirconium oxide at a high resolution. UV–visible spectroscopy determined an optical bandgap energy of about 2.44 eV, a refractive index of 2.17, and an optical conductivity of 3.15 × 1010 S/cm2. Forster resonance energy transfer between Zirconium dioxide and graphitic carbon nitride significantly enhanced photoluminescence emission. PL emission and color purity (45 %) of the optimized sample were examined using photoluminescence data. Electrical conductivity of ∼15.9 × 10−4 S/cm and dielectric constant of ∼14.77 were obtained from I to V and LCR meter measurements. These properties indicate that the pH-driven nanocomposite exhibits optimized electron-hole recombination rates, electrical conductivity, and suitable bandgap energy, making its potential impact as an emissive layer material for OLED applications.

Time-Resolved Mechanism of Positive Aging in InP Quantum-Dot Light-Emitting Diodes.

Positive aging has been reported to be effective for enhancing electroluminescence characteristics of quantum dot (QD) based optoelectrical devices. This study investigated the intricate mechanisms underlying the positive aging effect in quantum-dot light-emitting diodes (QLEDs) influenced by encapsulation with ultraviolet-curable resin. A 120-h analysis assessed the impact of the resin on the electron transport layer and emission layer, utilizing a strategically positioned perfluorinated ionomer (PFI) interlayer. The PFI layer effectively delayed the Al2O3 formation at the zinc magnesium oxide (ZMO)/Al interface and further reduced the interactions within the QD/ZMO interface, thereby curtailing exciton quenching at the interfaces. The time-sequential effect of positive aging demonstrated that resin encapsulation effectively passivates the ZMO surfaces after 12 h. The positive aging facilitated the reaction between aluminum and oxygen from ZMO, contributing to Al2O3 formation within 48 h of aging. Furthermore, positive aging passivated the defect states of the QD surface and the QD/ZMO interface, reducing exciton quenching at the QD or QD/ZMO interface. The enhanced electron injection and reduced exciton quenching resulted in aged InP QLEDs, exhibiting an external quantum efficiency of 12.04%. This is a significant increase from the 3.16% observed in the control device. Finally, a sequential mechanism of positive aging in InP QLEDs was devised, providing new insights into the time-related operation of aging agents. This study elucidates an advanced time-resolved mechanism of positive aging, thereby offering valuable insights into the intricate dynamics of excitons within the domain of QLED physics.

Polymer Hosts Containing Carbazole-Dibenzothiophene-Based Pendants for Application in High-Performance Solution-Processed TADF-OLEDs.

The film-forming capability of the host plays a crucial role in effectively forming a light-emitting layer through a solution process in organic light-emitting diodes (OLEDs). In this study, we synthesized two side-chain polymer hosts, PCz-DBT and P2Cz-DBT, consisting of carbazole and dibenzothiophene. The synthesis was carried out through radical polymerization using styrene-based host monomers. Their photophysical characteristics and molecular energy levels are similar to those of the reference small molecule hosts, namely, Cz-DBT and 2Cz-DBT. However, compared to the small-molecule hosts Cz-DBT and 2Cz-DBT, the two polymer hosts showed high thermal stability and good film-forming properties in the neat and host-emitter blend films. Specifically, bluish-green multiple-resonance (MR) thermally activated delayed fluorescence (TADF) OLEDs, fabricated via solution processing with an emissive layer based on P2Cz-DBT, exhibited remarkable performance. These devices achieved a maximum external quantum efficiency of 17.4% without utilizing a hole transport layer. This polymer host design strategy is considered to significantly contribute to enhancing the performance of TADF-OLEDs fabricated through solution processing.

Synthesis, Photoluminescence, and Electroluminescence of Phosphorescent Dipyrido[3,2-a;2'3'-c]phenazine-Platinum(II) Complexes Bearing Hole-Transporting Acetylide Ligands.

In this study, novel phosphorescent dipyrido[3,2-a;2'3'-c]phenazine (dppz)-platinum(II)-phenylacetylide complexes were developed to fabricate non-doped organic light-emitting diodes (OLED) by solution-processing. To facilitate the charge carrier injection into the emitting layer (EML), 3,6-di-tert-butylcarbazole-functinalized phenylacetylides were employed. As for the dppz ligand, 9,9-dihexylfluoren-2-yl and 4-hexylthiophen-2-yl side-arms were introduced to the 2,7-positions, which led to reddish orange and red photoluminescence (PL), respectively, in solution and film states (PL wavelength: ca. 600 and ca. 625 nm, respectively). The carbazole-appended phenylacetylide ligands hardly affected the emission color, although unsubstituted phenylacetylides gave rise to aggregate- or excimer-based near-infrared PL with a low quantum yield. Two types of non-doped OLEDs were fabricated: single-layer and multilayer devices. In both devices, the organic layers were fabricated by spin-coating, and the EML consisted of a neat film of the corresponding platinum(II) complex. Therein, electroluminescence spectra corresponding to those of PL were observed. The single-layer devices exhibited low device efficiencies due to a deteriorated charge carrier balance. The multilayer devices possessed hole- and electron-transporting layers on the anode and cathode sides of the EML, respectively. Owing to an improved charge carrier balance, the multilayer devices exhibited higher device performance, affording considerably improved values of luminance and external quantum efficiency.

(Invited) Optical Probes for Resonance-Enhanced Gold Growth on Nanooptical Substrates

We investigate light-stimulated growth of gold metal lines to technically mimic the growth of long-range axonal connections for neuromorphic computing architectures. Photocatalytic gold growth from an aqueous gold chloride precursor solution (HAuCl4) on a photoactive titanium dioxide layer is used. It is known that local gold growth may be obtained by UV illumination through a shadow mask [1]. To obtain a wavelength and angle dependent growth of metal lines – and thus stimulus-dependent resistances – we suggest to employ a nanooptical template. Inspired by the typical number of 2 to 10 connections to a node found, e.g., in the neuronal system of the biological species Hydra, we decided on the implementation of a hexagonal design. The edges are formed by periodic grating nanostructures with 10 to 20 periods and a grating pitch of 170 nm to 210 nm for excitation in the UV. In order to investigate the resonant optical enhancement, we employ optical probes. It is well known that colloidal quantum dots show enhanced fluorescence emission on photonic crystal surfaces due to resonant excitation and resonant outcoupling [2]. In our initial experiments for investigation of the resonant enhancement, we use 4,4’-Bis(2,2-diphenylvinyl)-1,1’-biphenyl (DBVBi) as the emitter material. Its absorption maximum matches the excitation laser at 355 nm and fluorescence in the visible spectrum around 455 nm may be monitored with our camera and spectrometer setup.The nanostructure master was fabricated by electron-beam lithography (Kelvin Nanotechnology Ltd.) according to our design. We transfer the nanostructure pattern onto 1.1 mm thick soda-lime glass substrates by UV-nanoimprint lithography. Subsequently, a 100 nm titanium dioxide layer is deposited. The 150 nm emissive DBVBi layer is then added by thermal evaporation. The samples are characterized optically with a camera setup and magnifying optics on an in-plane rotatable xy-stage. We use a Cobolt Zouk 355 nm 10 mW laser to excite the emissive layer. The output power of the laser is set to 2 mW and its output beam is widened with a collimating lens setup to a diameter of approximately 1.5 mm². The widened beam is essential to obtain a homogeneous excitation. We observe the successful resonant excitation by the higher emission intensity of DPVBi in specific regions of the nanostructure at specific excitation angles. Already for 10 periods of the grating structure resonance effects are observed. A stronger enhancement is obtained for 20 periods. Further, the enhancement depends on the grating pitch as connections with nanograting pitches below 190 nm are no longer visible. They do not meet the criteria for resonant excitation.This method of using optical probes on the nanooptical template works well for initial characterization of the resonance enhancement at different excitation angles. Now the setup is ready for performing gold growth under different excitation conditions. Without the additional emissive layer, the waveguide thickness change needs to be compensated with an increased titanium dioxide layer thickness. For online monitoring of the resonant enhancement during growth optical probes may be employed below the photoactive titanium dioxide layer. It is expected that the resonance enhancement is reduced with the addition of gold due to the increased absorption and thus reduced quality factor as was previously studied in the context of nanostructured OLEDs [3].We acknowledge funding by the DFG (German Research Foundation) with the CRC 1461- Neurotronics (Project-ID 434434223 – SFB 1461).[1] S. Veziroglu et al. (2018). Photocatalytic growth of hierarchical au needle clusters on highly active TiO2 thin film. Advanced Materials Interfaces, 5(15), 1800465.[2] N. Ganesh et al. (2007). Enhanced fluorescence emission from quantum dots on a photonic crystal surface. Nature nanotechnology, 2(8), 515-520.[3] J. Buhl et al. (2023). Resonance‐Based Directional Light Emission from Organic Light‐Emitting Diodes: Comparing Integrated Nanopatterns and Color Conversion Waveguide Gratings. Advanced Photonics Research, 4(2), 2200143. Figure 1. (Left) Fluorescence image of optical probe layer on nanooptical substrate for 355 nm laser excitation. (Middle) Schematic of nanooptical substrate with grating pitch (in nm) and number of periods given. Same colors represent identical grating features. (Right) Field emission scanning electron microscopy (FESEM) image of one node with 6 connections. Figure 1