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Zhang X, Ràfols-Ribé J, Mindemark J, Tang S, Lindh M, Gracia-Espino E, Larsen C, Edman L. Efficiency Roll-Off in Light-Emitting Electrochemical Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2310156. [PMID: 38211953 DOI: 10.1002/adma.202310156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/28/2023] [Indexed: 01/13/2024]
Abstract
Understanding "efficiency roll-off" (i.e., the drop in emission efficiency with increasing current) is critical if efficient and bright emissive technologies are to be rationally designed. Emerging light-emitting electrochemical cells (LECs) can be cost- and energy-efficiently fabricated by ambient-air printing by virtue of the in situ formation of a p-n junction doping structure. However, this in situ doping transformation renders a meaningful efficiency analysis challenging. Herein, a method for separation and quantification of major LEC loss factors, notably the outcoupling efficiency and exciton quenching, is presented. Specifically, the position of the emissive p-n junction in common singlet-exciton emitting LECs is measured to shift markedly with increasing current, and the influence of this shift on the outcoupling efficiency is quantified. It is further verified that the LEC-characteristic high electrochemical-doping concentration renders singlet-polaron quenching (SPQ) significant already at low drive current density, but also that SPQ increases super-linearly with increasing current, because of increasing polaron density in the p-n junction region. This results in that SPQ dominates singlet-singlet quenching for relevant current densities, and significantly contributes to the efficiency roll-off. This method for deciphering the LEC efficiency roll-off can contribute to a rational realization of all-printed LEC devices that are efficient at highluminance.
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Affiliation(s)
- Xiaoying Zhang
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
| | - Joan Ràfols-Ribé
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
| | - Jonas Mindemark
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, SE-751 21, Sweden
| | - Shi Tang
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
| | - Mattias Lindh
- Sustainable Resource Conversion unit, Biorefinery and Energy department, RISE Research Institutes of Sweden AB, Storgatan 65, Umeå, SE-90330, Sweden
| | - Eduardo Gracia-Espino
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
| | - Christian Larsen
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
- Wallenberg Initiative Materials Science for Sustainability, Department of Physics, Umeå University, Umeå, SE-90187, Sweden
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2
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Lavarda G, Berghuis AM, Joseph K, van der Tol JJB, Murai S, Gómez Rivas J, Meijer EW. Tunable emission from H-type supramolecular polymers in optical nanocavities. Chem Commun (Camb) 2024; 60:2812-2815. [PMID: 38362956 PMCID: PMC10913141 DOI: 10.1039/d3cc05877h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/08/2024] [Indexed: 02/17/2024]
Abstract
H-type supramolecular polymers with preferred helicity and highly efficient emission have been prepared from the self-assembly of chiral tetraphenylene-based monomers. Implementation of the one-dimensional fibers into dielectric nanoparticle arrays allows for a significant reshaping of fluorescence due to weak light-matter coupling.
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Affiliation(s)
- Giulia Lavarda
- Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands.
| | - Anton M Berghuis
- Eindhoven Hendrik Casimir Institute and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands
| | - Kripa Joseph
- Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands.
| | - Joost J B van der Tol
- Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands.
| | - Shunsuke Murai
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 6158510, Japan
| | - Jaime Gómez Rivas
- Eindhoven Hendrik Casimir Institute and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands
| | - E W Meijer
- Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands.
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3
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Ràfols-Ribé J, Zhang X, Larsen C, Lundberg P, Lindh EM, Mai CT, Mindemark J, Gracia-Espino E, Edman L. Controlling the Emission Zone by Additives for Improved Light-Emitting Electrochemical Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107849. [PMID: 34891219 DOI: 10.1002/adma.202107849] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/07/2021] [Indexed: 06/13/2023]
Abstract
The position of the emission zone (EZ) in the active material of a light-emitting electrochemical cell (LEC) has a profound influence on its performance because of microcavity effects and doping- and electrode-induced quenching. Previous attempts of EZ control have focused on the two principal constituents in the active material-the organic semiconductor (OSC) and the mobile ions-but this study demonstrates that it is possible to effectively control the EZ position through the inclusion of an appropriate additive into the active material. More specifically, it is shown that a mere modification of the end group on an added neutral compound, which also functions as an ion transporter, results in a shifted EZ from close to the anode to the center of the active material, which translates into a 60% improvement of the power efficiency. This particular finding is rationalized by a lowering of the effective electron mobility of the OSC through specific additive: OSC interactions, but the more important generic conclusion is that it is possible to control the EZ position, and thereby the LEC performance, by the straightforward inclusion of an easily tuned additive in the active material.
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Affiliation(s)
- Joan Ràfols-Ribé
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
| | - Xiaoying Zhang
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
| | - Christian Larsen
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
| | - Petter Lundberg
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
| | - E Mattias Lindh
- RISE Energy Technology Center AB, Industrigatan 1, Piteå, SE-941 38, Sweden
| | - Cuc Thu Mai
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, SE-751 21, Sweden
| | - Jonas Mindemark
- Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, SE-751 21, Sweden
| | - Eduardo Gracia-Espino
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Umeå University, Umeå, SE-90187, Sweden
- LunaLEC AB, Umeå University, Umeå, SE-90187, Sweden
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4
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Jeong WJ, Lee JI, Kwak HJ, Jeon JM, Shin DY, Kang MS, Kim JY. Effect of Optical and Morphological Control of Single-Structured LEC Device. MICROMACHINES 2021; 12:mi12070843. [PMID: 34357253 PMCID: PMC8303555 DOI: 10.3390/mi12070843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 11/30/2022]
Abstract
We investigated the performance of single-structured light-emitting electrochemical cell (LEC) devices with Ru(bpy)3(PF6)2 polymer composite as an emission layer by controlling thickness and heat treatment. When the thickness was smaller than 120–150 nm, the device performance decreased because of the low optical properties and non-dense surface properties. On the other hand, when the thickness was over than 150 nm, the device had too high surface roughness, resulting in high-efficiency roll-off and poor device stability. With 150 nm thickness, the absorbance increased, and the surface roughness was low and dense, resulting in increased device characteristics and better stability. The heat treatment effect further improved the surface properties, thus improving the device characteristics. In particular, the external quantum efficiency (EQE) reduction rate was shallow at 100 °C, which indicates that the LEC device has stable operating characteristics. The LEC device exhibited a maximum luminance of 3532 cd/m2 and an EQE of 1.14% under 150 nm thickness and 100 °C heat treatment.
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Affiliation(s)
- Woo Jin Jeong
- Department of Semiconductor Engineering, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, Korea; (W.J.J.); (H.J.K.); (J.M.J.); (D.Y.S.)
| | - Jong Ik Lee
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04107, Korea; (J.I.L.); (M.S.K.)
| | - Hee Jung Kwak
- Department of Semiconductor Engineering, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, Korea; (W.J.J.); (H.J.K.); (J.M.J.); (D.Y.S.)
| | - Jae Min Jeon
- Department of Semiconductor Engineering, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, Korea; (W.J.J.); (H.J.K.); (J.M.J.); (D.Y.S.)
| | - Dong Yeol Shin
- Department of Semiconductor Engineering, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, Korea; (W.J.J.); (H.J.K.); (J.M.J.); (D.Y.S.)
| | - Moon Sung Kang
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04107, Korea; (J.I.L.); (M.S.K.)
- Institute of Emergent Materials, Sogang University, Seoul 04107, Korea
| | - Jun Young Kim
- Department of Semiconductor Engineering, Gyeongsang National University, 501 Jinjudaero, Jinju 52828, Korea; (W.J.J.); (H.J.K.); (J.M.J.); (D.Y.S.)
- Correspondence: ; Tel.: +82-55-772-1732
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5
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Tang YH, Chiu YC, Luo D, Lien JY, Yi RH, Lin CH, Yang ZP, Lu CW, Su HC. Hybrid White-Light-Emitting Electrochemical Cells Based on a Blue Cationic Iridium(III) Complex and Red Quantum Dots. Chemistry 2020; 26:13668-13676. [PMID: 33463782 DOI: 10.1002/chem.202001994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Indexed: 01/26/2023]
Abstract
Solid-state white light-emitting electrochemical cells (LECs) show promising advantages of simple solution fabrication processes, low operation voltage, and compatibility with air-stable cathode metals, which are required for lighting applications. To date, white LECs based on ionic transition metal complexes (iTMCs) have shown higher device efficiencies than white LECs employing other types of materials. However, lower emission efficiencies of red iTMCs limit further improvement in device performance. As an alternative, efficient red CdZnSeS/ZnS core/shell quantum dots were integrated with a blue iTMC to form a hybrid white LEC in this work. By achieving good carrier balance in an appropriate device architecture, a peak external quantum efficiency and power efficiency of 11.2 % and 15.1 lm W-1, respectively, were reached. Such device efficiency is indeed higher than those of the reported white LECs based on host-guest iTMCs. Time- and voltage-dependent electroluminescence (EL) characteristics of the hybrid white LECs were studied by means of the temporal evolution of the emission-zone position extracted by fitting the simulated and measured EL spectra. The working principle of the hybrid white LECs was clarified, and the high device efficiency makes potential new white-emitting devices suitable for solid-state lighting technology possible.
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Affiliation(s)
- Ya-Han Tang
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan, 71150, Taiwan
| | - Yi-Chan Chiu
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan, 71150, Taiwan
| | - Dian Luo
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan, 71150, Taiwan
| | - Jiun-Yi Lien
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan, 70101, Taiwan
| | - Rong-Huei Yi
- Department of Applied Chemistry, Providence University, Taichung, 43301, Taiwan
| | - Ching-Hsuan Lin
- Department of Applied Chemistry, Providence University, Taichung, 43301, Taiwan
| | - Zu-Po Yang
- Institute of Photonic System, National Chiao Tung University, Tainan, 71150, Taiwan
| | - Chin-Wei Lu
- Department of Applied Chemistry, Providence University, Taichung, 43301, Taiwan
| | - Hai-Ching Su
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan, 71150, Taiwan
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6
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Yi RH, Lo CL, Luo D, Lin CH, Weng SW, Lu CW, Liu SW, Chang CH, Su HC. Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells. ACS APPLIED MATERIALS & INTERFACES 2020; 12:14254-14264. [PMID: 32155040 DOI: 10.1021/acsami.9b23300] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Light-emitting electrochemical cells (LECs) show high technical potential for display and lighting utilizations owing to the superior properties of solution processability, low operation voltage, and employing inert cathodes. For maximizing the device efficiency, three approaches including development of efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction have been reported. However, most reported works focused on only one of the three optimization approaches. In this work, a combinational approach is demonstrated to optimize the device efficiency of LECs. A sophisticatedly designed yellow complex exhibiting a superior steric hindrance and a good carrier balance is proposed as the emissive material of light-emitting electrochemical cells and thus the external quantum efficiency (EQE) is up to 13.6%. With an improved carrier balance and reduced self-quenching by employing the host-guest strategy, the device EQE can be enhanced to 16.9%. Finally, a diffusive layer embedded between the glass substrate and the indium-tin-oxide layer is utilized to scatter the light trapped in the layered device structure, and consequently, a high EQE of 23.7% can be obtained. Such an EQE is impressive and consequently proves that the proposed combinational approach including adopting efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction is effective in realizing highly efficient LECs.
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Affiliation(s)
- Rong-Huei Yi
- Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan
| | - Chieh-Liang Lo
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan 71150, Taiwan
| | - Dian Luo
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan 71150, Taiwan
| | - Chien-Hsiang Lin
- Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan
| | - Shu-Wen Weng
- Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan
| | - Chin-Wei Lu
- Department of Applied Chemistry, Providence University, Taichung 43301, Taiwan
| | - Shun-Wei Liu
- Department of Electronic Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan
| | - Chih-Hao Chang
- Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan
| | - Hai-Ching Su
- Institute of Lighting and Energy Photonics, National Chiao Tung University, Tainan 71150, Taiwan
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7
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Jiménez-Solano A, Martínez-Sarti L, Pertegás A, Lozano G, Bolink HJ, Míguez H. Dipole reorientation and local density of optical states influence the emission of light-emitting electrochemical cells. Phys Chem Chem Phys 2019; 22:92-96. [PMID: 31802085 DOI: 10.1039/c9cp05505c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we analyze the temporal evolution of the electroluminescence of light-emitting electrochemical cells (LECs), a thin-film light-emitting device, in order to maximize the luminous power radiated by these devices. A careful analysis of the spectral and angular distribution of the emission of LECs fabricated under the same experimental conditions allows describing the dynamics of the spatial region from which LECs emit, i.e. the generation zone, as bias is applied. This effect is mediated by dipole reorientation within such an emissive region and its optical environment, since its spatial drift yields a different interplay between the intrinsic emission of the emitters and the local density of optical states of the system. Our results demonstrate that engineering the optical environment in thin-film light-emitting devices is key to maximize their brightness.
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Affiliation(s)
- Alberto Jiménez-Solano
- Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Calle Américo Vespucio 49, 41092, Sevilla, Spain.
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8
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Lundberg P, Tsuchiya Y, Lindh EM, Tang S, Adachi C, Edman L. Thermally activated delayed fluorescence with 7% external quantum efficiency from a light-emitting electrochemical cell. Nat Commun 2019; 10:5307. [PMID: 31757959 PMCID: PMC6874610 DOI: 10.1038/s41467-019-13289-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/31/2019] [Indexed: 11/09/2022] Open
Abstract
We report on light-emitting electrochemical cells, comprising a solution-processed single-layer active material and air-stabile electrodes, that exhibit efficient and bright thermally activated delayed fluorescence. Our optimized devices delivers a luminance of 120 cd m-2 at an external quantum efficiency of 7.0%. As such, it outperforms the combined luminance/efficiency state-of-the art for thermally activated delayed fluorescence light-emitting electrochemical cells by one order of magnitude. For this end, we employed a polymeric blend host for balanced electrochemical doping and electronic transport as well as uniform film formation, an optimized concentration (<1 mass%) of guest for complete host-to-guest energy transfer at minimized aggregation and efficient emission, and an appropriate concentration of an electrochemically stabile electrolyte for desired doping effects. The generic nature of our approach is manifested in the attainment of bright and efficient thermally activated delayed fluorescence emission from three different light-emitting electrochemical cells with invariant host:guest:electrolyte number ratio.
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Affiliation(s)
- Petter Lundberg
- The Organic Photonics and Electronics Group, Umeå University, SE-901 87, Umeå, Sweden
| | - Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.,JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - E Mattias Lindh
- The Organic Photonics and Electronics Group, Umeå University, SE-901 87, Umeå, Sweden
| | - Shi Tang
- The Organic Photonics and Electronics Group, Umeå University, SE-901 87, Umeå, Sweden.,LunaLEC AB, Linnaeus väg 24, SE-901 87, Umeå, Sweden
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.,JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.,Department of Chemistry and Biochemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.,International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Umeå University, SE-901 87, Umeå, Sweden. .,LunaLEC AB, Linnaeus väg 24, SE-901 87, Umeå, Sweden.
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9
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Gerz I, Lindh EM, Thordarson P, Edman L, Kullgren J, Mindemark J. Oligomer Electrolytes for Light-Emitting Electrochemical Cells: Influence of the End Groups on Ion Coordination, Ion Binding, and Turn-on Kinetics. ACS APPLIED MATERIALS & INTERFACES 2019; 11:40372-40381. [PMID: 31621280 DOI: 10.1021/acsami.9b15233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The electrolyte is an essential constituent of the light-emitting electrochemical cell (LEC), since its operating mechanism is dependent on the redistribution of mobile ions in the active layer. Recent developments of new ion transporters have yielded high-performance devices, but knowledge about the interactions between the ionic species and the ion transporters and the influence of these interactions on the LEC performance is lacking. We therefore present a combined computational and experimental effort that demonstrates that the selection of the end group in a star-branched oligomeric ion transporter based on trimethylolpropane ethoxylate has a paramount influence on the ionic interactions in the electrolyte and thereby also on the performance of the corresponding LECs. With hydroxyl end groups, the cation from the salt is strongly coordinated to the ion transporter, which leads to suppression of ion pairing, but the penalty is a hindered ion release and a slow turn-on for the LEC devices. With methoxy end groups, an intermediate coordination strength is seen together with the formation of contact ion pairs, but the LEC performance is very good with fast turn-on. Using a series of ion transporters with alkyl carbonate end groups, the ion transporter:cation coordination strength is lowered further, but the turn-on kinetics are slower than what is seen for devices comprising the methoxy end-capped ion transporter.
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Affiliation(s)
- Isabelle Gerz
- Department of Chemistry-Ångström Laboratory , Uppsala University , Box 538, SE-751 21 Uppsala , Sweden
| | - E Mattias Lindh
- The Organic Photonics and Electronics Group, Department of Physics , Umeå University , SE-901 87 Umeå , Sweden
| | - Pall Thordarson
- School of Chemistry, the Australian Centre for Nanomedicine and the ARC Centre of Excellence in Convergent Bio-Nano Science & Technology , University of New South Wales , Sydney , NSW 2052 , Australia
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Department of Physics , Umeå University , SE-901 87 Umeå , Sweden
| | - Jolla Kullgren
- Department of Chemistry-Ångström Laboratory , Uppsala University , Box 538, SE-751 21 Uppsala , Sweden
| | - Jonas Mindemark
- Department of Chemistry-Ångström Laboratory , Uppsala University , Box 538, SE-751 21 Uppsala , Sweden
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10
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Lindh EM, Lundberg P, Lanz T, Edman L. Optical analysis of light-emitting electrochemical cells. Sci Rep 2019; 9:10433. [PMID: 31320711 PMCID: PMC6639418 DOI: 10.1038/s41598-019-46860-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/05/2019] [Indexed: 11/09/2022] Open
Abstract
The light-emitting electrochemical cell (LEC) is a contender for emerging applications of light, primarily because it offers low-cost solution fabrication of easily functionalized device architectures. The attractive properties originate in the in-situ formation of electrochemically doped transport regions that enclose an emissive intrinsic region, but the understanding of how this intricate doping structure affects the optical performance of the LEC is largely lacking. We combine angle- and doping-dependent measurements and simulations, and demonstrate that the emission zone in our high-performance LEC is centered at ~30% of the active-layer thickness (dal) from the anode. We further find that the emission intensity and efficiency are undulating with dal, and establish that the first emission maximum at dal ~ 100 nm is largely limited by the lossy coupling of excitons to the doping regions, whereas the most prominent loss channel at the second maximum at dal ~ 300 nm is wave-guided modes.
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Affiliation(s)
- E Mattias Lindh
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden
| | - Petter Lundberg
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden
| | - Thomas Lanz
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden.
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11
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Strassel K, Ramanandan SP, Abdolhosseinzadeh S, Diethelm M, Nüesch F, Hany R. Solution-Processed Organic Optical Upconversion Device. ACS APPLIED MATERIALS & INTERFACES 2019; 11:23428-23435. [PMID: 31179678 DOI: 10.1021/acsami.9b06732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Imaging in the near-infrared (NIR) is getting increasingly important for applications such as machine vision or medical imaging. NIR-to-visible optical upconverters consist of a monolithic stack of a NIR photodetector and a visible light-emitting unit. Such devices convert NIR light directly to visible light and allow capturing a NIR image with an ordinary camera. Here, five-layer organic solution-processed upconverters (OUCs) are reported which consist of a squaraine dye NIR photodetector and a fluorescent poly( para-phenylene vinylene) copolymer (super yellow)-based organic light-emitting diode (OLED) or light-emitting electrochemical cell (LEC), respectively. Both OLED-OUCs and LEC-OUCs convert NIR light at 980 nm to yellow light at around 575 nm with comparable device metrics of performance, such as a turn-on voltage of 2.7-2.9 V and a NIR-to-visible photon conversion efficiency of around 1.6%. Because of the presence of a salt in the emitting layer, the LEC-OUC is a temporally dynamic device. The LEC-OUC turn-on and relaxation behavior is characterized in detail. It is demonstrated that a particular ionic distribution and thereby the LEC-OUC status can be frozen by storing the device in the presence of a small voltage applied. This provides a test chart for quantitative measurements.
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Affiliation(s)
- Karen Strassel
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
- Institute of Chemical Sciences and Engineering , Ecole Polytechnique Fédérale de Lausanne, EPFL , Station 6 , CH-1015 Lausanne , Switzerland
| | - Santhanu Panikar Ramanandan
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
- Institute of Materials Science and Engineering , Ecole Polytechnique Fédérale de Lausanne, EPFL , Station 12 , CH-1015 Lausanne , Switzerland
| | - Sina Abdolhosseinzadeh
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
- Institute of Materials Science and Engineering , Ecole Polytechnique Fédérale de Lausanne, EPFL , Station 12 , CH-1015 Lausanne , Switzerland
| | - Matthias Diethelm
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
- Institute of Materials Science and Engineering , Ecole Polytechnique Fédérale de Lausanne, EPFL , Station 12 , CH-1015 Lausanne , Switzerland
| | - Frank Nüesch
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
- Institute of Materials Science and Engineering , Ecole Polytechnique Fédérale de Lausanne, EPFL , Station 12 , CH-1015 Lausanne , Switzerland
| | - Roland Hany
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Functional Polymers , CH-8600 Dübendorf , Switzerland
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Hany R, Cremona M, Strassel K. Recent advances with optical upconverters made from all-organic and hybrid materials. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2019; 20:497-510. [PMID: 31191760 PMCID: PMC6542176 DOI: 10.1080/14686996.2019.1610057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/15/2019] [Accepted: 04/17/2019] [Indexed: 05/04/2023]
Abstract
The growing interest in near-infrared (NIR) imaging is explained by the increasing number of applications in this spectral range, which includes process monitoring and medical imaging. NIR-to-visible optical upconverters made by integrating a NIR photosensitive unit with a visible emitting unit convert incident NIR light to visible light, allowing imaging of a NIR scene directly with the naked eye. Optical upconverters made entirely from organic and hybrid materials - which include colloidal quantum dots, and metal-halide perovskites - enable low-cost and pixel-free NIR imaging. These devices have emerged as a promising addition to current NIR imagers based on inorganic semiconductor photodiode arrays interconnected with read-out integrated circuitry. Here, we review the recent progress in the field of optical upconverters made from organic and hybrid materials, explain their functionality and characterization, and identify open challenges and opportunities.
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Affiliation(s)
- Roland Hany
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Dübendorf, Switzerland
- CONTACT Roland Hany Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, CH-8600Dübendorf, Switzerland
| | - Marco Cremona
- Optoelectronic Molecular Laboratory, Physics Department, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Karen Strassel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Dübendorf, Switzerland
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Kawecki M, Hany R, Diethelm M, Jenatsch S, Grossmann Q, Bernard L, Hug HJ. Direct Measurement of Ion Redistribution and Resulting Modification of Chemical Equilibria in Polymer Thin Film Light-Emitting Electrochemical Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:39100-39106. [PMID: 30335938 DOI: 10.1021/acsami.8b14198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The redistribution of ions in light-emitting electrochemical cells (LECs) plays a key role in their functionality. The direct quantitative mapping of ion density distributions in operating realistic sandwich-type devices, however, has not been experimentally achieved. Here we operate high-performing [Super Yellow/trimethylolpropane ethoxylate/lithium trifluoromethanesulfonate (Li+CF3SO3-)] LEC devices inside a time-of-flight secondary ion mass spectrometer and cool the devices after different operation times to liquid nitrogen temperatures before depth profiling is performed. The results reveal the dependence of the elemental and molecular distributions across the device layer on operation conditions. We find that the ion displacements lead to a substantial shift of the local chemical equilibria governing the free ion concentration.
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Affiliation(s)
- Maciej Kawecki
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
- Department of Physics , University of Basel , CH-4056 Basel , Switzerland
| | - Roland Hany
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
| | - Matthias Diethelm
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
| | - Sandra Jenatsch
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
| | - Quirin Grossmann
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
| | - Laetitia Bernard
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
| | - Hans J Hug
- Empa, Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf , Switzerland
- Department of Physics , University of Basel , CH-4056 Basel , Switzerland
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