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Ultrathin Fully Printed Light-Emitting Electrochemical Cells with Arbitrary Designs on Biocompatible Substrates
摘要： Organic electronic devices are often highlighted in terms of cost-efficient solution processing and potential printability. However, few studies are reporting truly full-solution-processed devices taking into account the electrodes as well as all other layers. This results in a production method that only partially benefits from the cost efficiency of solution processing and that still depends on costly and elaborate techniques like evaporation and/or lithography. This lack of knowledge is addressed by presenting a truly fully printed light-emitting electrochemical cell on ultraflexible parylene C substrates usable for conformable electronics. All device parts are fabricated by industrial relevant printing-techniques under ambient atmosphere. Inkjet printing is used for the structuring of the device layout and is therefore able to implement and create arbitrary designs. Further layers are produced by blade coating which is well suited for the coating of large areas. The devices show stable operation at a luminance higher than 100 cd m?2 for 8.8 h, can reach a maximum brightness of 918 cd m?2, and exhibit a turn-on time of 40 s to reach 100 cd m?2. Moreover, biocompatible and biodegradable materials are utilized to allow potential applications in life science and bioelectronics.
关键词： fully printed electronics,light-emitting electrochemical cells,parylene,inkjet,bioelectronics,digital printing,conformable electronics
更新于2025-09-23 15:23:52
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Carbazole based ionic small molecule emitter for non-doped light-emitting electrochemical cells
摘要： Great efforts have been made to develop blue emitting organic small molecules for light-emitting electrochemical cells. Herein, blue emitting CPC (CarPhenCar) was synthesized and its emissive properties were studied. CPC exhibits blue fluorescence in toluene solution as well as in solid thin-films. CPC exhibits good thermal and electrochemical stabilities. Application of CPC molecule in solution processed light-emitting electrochemical cells resulted blue emission centered at 485 nm with brightness of 454 cd/m2, current efficiencies of 1.33 cd/A and external quantum efficiencies of 1.76%. These results adequately demonstrate the practicability of tuning the emission color of phenothiazine derivative into blue region.
关键词： Small molecule,ionic,light-emitting electrochemical cells,blue fluorescence
更新于2025-09-23 15:22:29
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Lighta??Emitting Electrochemical Cells Based on Colora??Tunable Inorganic Colloidal Quantum Dots
摘要： Large-area, ultrathin light-emitting devices currently inspire architects and interior and automotive designers all over the world. Light-emitting electrochemical cells (LECs) and quantum dot light-emitting diodes (QD-LEDs) belong to the most promising next-generation device concepts for future flexible and large-area lighting technologies. Both concepts incorporate solution-based fabrication techniques, which makes them attractive for low cost applications based on, for example, roll-to-roll fabrication or inkjet printing. However, both concepts have unique benefits that justify their appeal. LECs comprise ionic species in the active layer, which leads to the omission of additional organic charge injection and transport layers and reactive cathode materials, thus LECs impress with their simple device architecture. QD-LEDs impress with purity and opulence of available colors: colloidal quantum dots (QDs) are semiconducting nanocrystals that show high yield light emission, which can be easily tuned over the whole visible spectrum by material composition and size. Emerging technologies that unite the potential of both concepts (LEC and QD-LED) are covered, either by extending a typical LEC architecture with additional QDs, or by replacing the entire organic LEC emitter with QDs or perovskite nanocrystals, still keeping the easy LEC setup featured by the incorporation of mobile ions.
关键词： organic electronics,perovskites,luminescence,light-emitting electrochemical cells,quantum dots
更新于2025-09-23 15:19:57
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Phosphane tuning in heteroleptic [Cu(N^N)(P^P)] <sup>+</sup> complexes for light-emitting electrochemical cells
摘要： The synthesis and characterization of five [Cu(P^P)(N^N)][PF6] complexes in which P^P = 2,7-bis(tert-butyl)-4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (tBu2xantphos) or the chiral 4,5-bis(mesitylphenylphosphino)-9,9-dimethylxanthene (xantphosMes2) and N^N = 2,2’-bipyridine (bpy), 6-methyl-2,2’-bipyridine (6-Mebpy) or 6,6’-dimethyl-2,2’-bipyridine (6,6’-Me2bpy) are reported. Single crystal structures of four of the compounds confirm that the copper(I) centre is in a distorted tetrahedral environment. In [Cu(xantphosMes2)(6-Mebpy)][PF6], the 6-Mebpy unit is disordered over two equally populated orientations and this disorder parallels a combination of two dynamic processes which we propose for [Cu(xantphosMes2)(N^N)]+ cations in solution. Density functional theory (DFT) calculations reveal that the energy difference between the two conformers observed in the solid-state structure of [Cu(xantphosMes2)(6-Mebpy)][PF6] differ in energy by only 0.28 kcal mol?1. Upon excitation into the MLCT region (λexc = 365 nm), the [Cu(P^P)(N^N)][PF6] compounds are yellow to orange emitters. Increasing the number of Me groups in the bpy unit shifts the emission to higher energies, and moves the Cu+/Cu2+ oxidation to higher potentials. Photoluminescence quantum yields (PLQYs) of the compounds are low in solution, but in the solid state PLQYs of up to 59% (for [Cu(tBu2xantphos)(6,6’-Me2bpy)]+) are observed. Increased excited-state lifetimes at low temperature are consistent with the complexes exhibiting thermally activated delayed fluorescence (TADF). This is supported by the small energy difference calculated between the lowest-energy singlet and triplet excited states (0.17–0.25 eV). The compounds were tested in simple bilayer light-emitting electrochemical cells (LECs). The optoelectronic performances of complexes containing xantphosMes2 were generally lower with respect to those with tBu2xantphos, which led to bright and efficient devices. The best performing LECs were obtained for the complex [Cu(tBu2xantphos)(6,6’-Me2bpy)][PF6] due to the increased steric hindrance at the N^N ligand, resulting in higher PLQY.
关键词： photoluminescence quantum yields,heteroleptic copper complexes,light-emitting electrochemical cells,thermally activated delayed fluorescence,Phosphane tuning
更新于2025-09-19 17:15:36
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Remote Modification of Bidentate Phosphane Ligands Controlling the Photonic Properties in Their Complexes: Enhanced Performance of [Cu(RNa??xantphos)(N <sup>^</sup> N)][PF <sub/>6</sub> ] in Lighta??Emitting Electrochemical Cells
摘要： A series of copper(I) complexes of the type [Cu(HN-xantphos)(N^N)][PF6] and [Cu(BnN-xantphos)(N^N)][PF6], in which N^N = bpy, Mebpy, and Me2bpy, HN-xantphos = 4,6-bis(diphenylphosphanyl)-10H-phenoxazine and BnN-xantphos = 10-benzyl-4,6-bis(diphenylphosphanyl)-10H-phenoxazine is described. The single crystal structures of [Cu(HN-xantphos)(Mebpy)][PF6] and [Cu(BnN-xantphos)(Me2bpy)][PF6] confirm the presence of N^N and P^P chelating ligands with the copper(I) atoms in distorted coordination environments. Solution electrochemical and photophysical properties of the BnN-xantphos-containing compounds (for which the highest-occupied molecular orbital is located on the phenoxazine moiety) are reported. The first oxidation of [Cu(BnN-xantphos)(N^N)][PF6] occurs on the BnN-xantphos ligand. Time-dependent density functional theory (TD-DFT) calculations have been used to analyze the solution absorption spectra of the [Cu(BnN-xantphos)(N^N)][PF6] compounds. In the solid-state, the compounds show photoluminescence in the range 518–555 nm for [Cu(HN-xantphos)(N^N)][PF6] and 520–575 nm for [Cu(BnN-xantphos)(N^N)][PF6] with a blue-shift on going from bpy to Mebpy to Me2bpy. [Cu(BnN-xantphos)(Me2bpy)][PF6] exhibits a solid-state photoluminescence quantum yield of 55% with an excited state lifetime of 17.4 μs. Bright light-emitting electrochemical cells are obtained using this complex, and it is shown that the electroluminescence quantum yield can be enhanced by using less conducting hole injection layers.
关键词： DFT calculations,electroluminescence,photophysics,light-emitting electrochemical cells,ionic copper complexes
更新于2025-09-19 17:13:59
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Designing the Next Generation of Light-Emitting Electrochemical Cells
摘要： In this article, the recent achievements toward the next generation of LECs are summarized. The term next generation is founded on the impressive efforts of the scientific community to open up different pathways to enrich the library of suitable emitters for LECs with the long-term aim to meet the requirements of green photonics, that is, low-cost, high-performing, and thin-film lighting sources based on environmentally friendly and abundant materials. As an example, small molecules featuring TADF are considered the third generation of electroluminescent materials in OLEDs. Unlike this type of lighting devices, several groups have shown that LECs feature moderate performances in terms of luminance and efficacy values compared to OLEDs, but this technology bears a great future potential due to (i) the simple device architecture and active layer composition, (ii) the intolerance to the type of substrates and deposition techniques, and (iii) the good performance under ambient conditions.
关键词： green photonics,LECs,OLEDs,electroluminescent materials,Light-emitting electrochemical cells
更新于2025-09-10 09:29:36
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A dynamic bipolar electrode array for visualized screening of electrode materials in light-emitting electrochemical cells
摘要： Charge injection at a metal/semiconductor interface is of paramount importance for many chemical and physical processes. The dual injection of electrons and holes, for example, is necessary for electroluminescence in organic light-emitting devices. In an electrochemical cell, charge transfer across the electrode interface is responsible for redox reactions and faradic current flow. In this work, we use polymer light-emitting electrochemical cells (PLECs) to visually assess the ability of metals to inject electronic charges into a luminescent polymer. Silver, aluminum or gold micro-discs are deposited between the two driving electrodes of the PLEC in the form of a horizontal array. When the PLEC is polarized, the individual discs functioned as bipolar electrodes (BPEs) to induce redox p- and n-doping reactions at their extremities, which are visualized as strongly photoluminescence-quenched growth in the luminescence polymer. The three metals initially generate highly distinct doping patterns that are consistent with differences in their work function. Over time, the doped regions continue to grow in size. Quantitative analysis of the n/p area ratio reveals an amazing convergence to a single value for all 39 BPEs, regardless of their metal type and large variation in the size of individual doped areas. We introduce the concept of a dynamic BPE, which transforms from an initial metal disc of fixed size to one that is a composite of p- and n-doped polymer joined by the initial metallic BPE. The internal structure of the dynamic BPE, as measured by the n/p area ratio, reflects only the properties of the mixed conductor of the PLEC active layer itself when the area ratio converges.
关键词： electrochemical doping,bipolar electrodes,light-emitting electrochemical cells,work function,electrode screening
更新于2025-09-09 09:28:46