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Fresta E, Dosso J, Cabanillas-Gonzalez J, Bonifazi D, Costa RD. Revealing the Impact of Heat Generation Using Nanographene-Based Light-Emitting Electrochemical Cells. ACS APPLIED MATERIALS & INTERFACES 2020; 12:28426-28434. [PMID: 32476401 DOI: 10.1021/acsami.0c06783] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Self-heating in light-emitting electrochemical cells (LECs) has been long overlooked, while it has a significant impact on (i) device chromaticity by changing the electroluminescent band shape, (ii) device efficiency because of thermal quenching and exciton dissociation reducing the external quantum efficiency (EQE), and (iii) device stability because of thermal degradation of excitons and eliminate doped species, phase separation, and collapse of the intrinsic emitting zone. Herein, we reveal, for the first time, a direct relationship between self-heating and the early changes in the device chromaticity as well as the magnitude of the error comparing theoretical/experimental EQEs-that is, an overestimation error of ca. 35% at usual pixel working temperatures of around 50 °C. This has been realized in LECs using a benchmark nanographene-that is, a substituted hexa-peri-hexabenzocoronene-as an emerging class of emitters with outstanding device performance compared to the prior art of small-molecule LECs-for example, luminances of 345 cd/m2 and EQEs of 0.35%. As such, this work is a fundamental contribution highlighting how self-heating is a critical limitation toward the optimization and wide use of LECs.
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Affiliation(s)
- Elisa Fresta
- IMDEA Materials Institute, Calle Eric Kandel 2, E-28906 Getafe, Madrid, Spain
- Departamento de Física Aplicada, Universidad Autónoma de Madrid, Calle Francisco Tomás y Valiente, 7, 28049 Madrid, Spain
| | - Jacopo Dosso
- School of Chemistry, Cardiff University, CF10 3AT Cardiff, Great Britain
| | | | - Davide Bonifazi
- School of Chemistry, Cardiff University, CF10 3AT Cardiff, Great Britain
- Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Rubén D Costa
- IMDEA Materials Institute, Calle Eric Kandel 2, E-28906 Getafe, Madrid, Spain
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2
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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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3
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Fresta E, Baumgärtner K, Cabanillas-Gonzalez J, Mastalerz M, Costa RD. Bright, stable, and efficient red light-emitting electrochemical cells using contorted nanographenes. NANOSCALE HORIZONS 2020; 5:473-480. [PMID: 32118226 DOI: 10.1039/c9nh00641a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This work rationalizes, for the first time, the electroluminescent behavior of a representative red-emitting contorted nanographene -i.e., hexabenzoovalene derivative - in small molecule light-emitting electrochemical cells (SM-LECs). This new emitter provides devices with irradiances of ca. 220 μW cm-2 (242 cd m-2), external quantum efficiencies (EQE) of 0.78% (<25% loss of the maximum theoretical EQE), and stabilities over 200 h. Upon optimizing the device architecture, the stability increased up to 3600 h (measured) and 13 000 h (extrapolated) at a high brightness of ca. 30 μW cm-2 (34 cd m-2). This represents a record stability at a high brightness level compared to the state-of-the-art SM-LECs (1000 h at 0.3 μW cm-2). In addition, we rationalized one of the very rare LEC examples in which the changes of the electroluminescence band shape relates to the dependence of the relative intensity of the vibrational peaks with electric field, as corroborated by dynamic electrochemical impedance spectroscopy assays. Nevertheless, this exclusive electroluminescence behavior does not affect the device color, realizing one of the most stable, bright, and efficient red-emitting SM-LECs up to date.
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Affiliation(s)
- Elisa Fresta
- IMDEA Materials Institute, Calle Eric Kandel 2, E-28906 Getafe, Madrid, Spain.
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4
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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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5
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Keller S, Prescimone A, Bolink H, Sessolo M, Longo G, Martínez-Sarti L, Junquera-Hernández JM, Constable EC, Ortí E, Housecroft CE. Luminescent copper(i) complexes with bisphosphane and halogen-substituted 2,2'-bipyridine ligands. Dalton Trans 2018. [PMID: 29790540 DOI: 10.1039/c8tc02882f] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Heteroleptic [Cu(P^P)(N^N)][PF6] complexes, where N^N is a halo-substituted 2,2'-bipyridine (bpy) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) have been synthesized and investigated. To stabilize the tetrahedral geometry of the copper(i) complexes, the steric demands of the bpy ligands have been increased by introducing 6- or 6,6'-halo-substituents in 6,6'-dichloro-2,2'-bipyridine (6,6'-Cl2bpy), 6-bromo-2,2'-bipyridine (6-Brbpy) and 6,6'-dibromo-2,2'-bipyridine (6,6'-Br2bpy). The solid-state structures of [Cu(POP)(6,6'-Cl2bpy)][PF6], [Cu(xantphos)(6,6'-Cl2bpy)][PF6]·CH2Cl2, [Cu(POP)(6-Brbpy)][PF6] and [Cu(xantphos)(6-Brbpy)][PF6]·0.7Et2O obtained from single crystal X-ray diffraction are described including the pressure dependence of the structure of [Cu(POP)(6-Brbpy)][PF6]. The copper(i) complexes with either POP or xantphos and 6,6'-Cl2bpy, 6-Brbpy and 6,6'-Br2bpy are orange-to-red emitters in solution and yellow-to-orange emitters in the solid state, and their electrochemical and photophysical properties have been evaluated with the help of density functional theory (DFT) calculations. The emission properties are strongly influenced by the substitution pattern that largely affects the geometry of the emitting triplet state. [Cu(POP)(6,6'-Cl2bpy)][PF6] and [Cu(xantphos)(6,6'-Cl2bpy)][PF6] show photoluminescence quantum yields of 15 and 17%, respectively, in the solid state, and these compounds were tested as luminophores in light-emitting electrochemical cells (LECs). The devices exhibit orange electroluminescence and very short turn-on times (<5 to 12 s). Maximum luminance values of 121 and 259 cd m-2 for [Cu(POP)(6,6'-Cl2bpy)][PF6] and [Cu(xantphos)(6,6'-Cl2bpy)][PF6], respectively, were achieved at an average current density of 100 A m-2. External quantum efficiencies of 1.2% were recorded for both complexes.
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Affiliation(s)
- Sarah Keller
- Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, CH-4058 Basel, Switzerland.
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6
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Kwack JH, Choi J, Park CH, Hwang H, Park YW, Ju BK. Simple method for fabricating scattering layer using random nanoscale rods for improving optical properties of organic light-emitting diodes. Sci Rep 2018; 8:14311. [PMID: 30254286 PMCID: PMC6156328 DOI: 10.1038/s41598-018-32538-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/05/2018] [Indexed: 11/09/2022] Open
Abstract
We investigated a low-temperature mask-free process for preparing random nanoscale rods (RNRs) as a scattering layer. The process involves spin coating and dry etching, which are already widely applied in industry. Our film exhibited 17-33% optical haze at 520 nm wavelength and 95% total transmittance in the visible range. Therefore, this film can be used as a scattering layer for improving viewing angle characteristics and decreasing substrate mode loss in organic light-emitting diodes (OLEDs). Specifically, we focussed on varying the height and density of the RNRs to control the optical characteristics. As a result, the OLEDs with RNRs revealed a variation in colour coordinates of Δ(x, y) = (0.007, 0.014) for a change in the viewing angle, which was superior to those without the RNRs that displayed a variation of Δ(x, y) = (0.020, 0.034) in CIE 1931. Moreover, the OLEDs with RNRs exhibited 31% enhanced external quantum efficiency compared to those of the OLEDs with the bare substrate. The flexibility of the polymer used for the RNRs and the plasma treatment suggests that the RNRs can be applied to flexible OLED displays and lighting systems.
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Affiliation(s)
- Jin Ho Kwack
- Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University Seoul, Seoul, 136-713, Republic of Korea.,Samsung Display Co., Samsung St. 181, Tangjeong-Myeon, Asan-City, Chungcheongnam-do, 31454, Republic of Korea
| | - Junhee Choi
- Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University Seoul, Seoul, 136-713, Republic of Korea
| | - Cheol Hwee Park
- Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University Seoul, Seoul, 136-713, Republic of Korea
| | - Ha Hwang
- Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University Seoul, Seoul, 136-713, Republic of Korea
| | - Young Wook Park
- School of Mechanical and ICT Convergence Engineering, SUN MOON University, Asan-City, Chungcheongnam-do, 31460, Republic of Korea.
| | - Byeong-Kwon Ju
- Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University Seoul, Seoul, 136-713, Republic of Korea.
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7
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Lindh EM, Lundberg P, Lanz T, Mindemark J, Edman L. The Weak Microcavity as an Enabler for Bright and Fault-tolerant Light-emitting Electrochemical Cells. Sci Rep 2018; 8:6970. [PMID: 29725061 PMCID: PMC5934366 DOI: 10.1038/s41598-018-25287-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/18/2018] [Indexed: 11/09/2022] Open
Abstract
The light-emitting electrochemical cell (LEC) is functional at substantial active-layer thickness, and is as such heralded for being fit for low-cost and fault-tolerant solution-based fabrication. We report here that this statement should be moderated, and that in order to obtain a strong luminous output, it is fundamentally important to fabricate LEC devices with a designed thickness of the active layer. By systematic experimentation and simulation, we demonstrate that weak optical microcavity effects are prominent in a common LEC system, and that the luminance and efficiency, as well as the emission color and the angular intensity, vary in a periodic manner with the active-layer thickness. Importantly, we demonstrate that high-performance light-emission can be attained from LEC devices with a significant active-layer thickness of 300 nm, which implies that low-cost solution-processed LECs are indeed a realistic option, provided that the device structure has been appropriately designed from an optical perspective.
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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
| | - Jonas Mindemark
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden.,Department of Chemistry - Ångström Laboratory, Uppsala University, SE-75121, Uppsala, Sweden
| | - Ludvig Edman
- The Organic Photonics and Electronics Group, Department of Physics, Umeå University, SE-90187, Umeå, Sweden.
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8
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Su HC. Optical Techniques for Light-Emitting Electrochemical Cells. Chempluschem 2018; 83:197-210. [DOI: 10.1002/cplu.201700455] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/05/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Hai-Ching Su
- Institute of Lighting and Energy Photonics; National Chiao Tung University; Tainan 71150 Taiwan
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9
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Martínez-Alonso M, Cerdá J, Momblona C, Pertegás A, Junquera-Hernández JM, Heras A, Rodríguez AM, Espino G, Bolink H, Ortí E. Highly Stable and Efficient Light-Emitting Electrochemical Cells Based on Cationic Iridium Complexes Bearing Arylazole Ancillary Ligands. Inorg Chem 2017; 56:10298-10310. [PMID: 28836770 DOI: 10.1021/acs.inorgchem.7b01167] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of bis-cyclometalated iridium(III) complexes of general formula [Ir(ppy)2(N∧N)][PF6] (ppy- = 2-phenylpyridinate; N∧N = 2-(1H-imidazol-2-yl)pyridine (1), 2-(2-pyridyl)benzimidazole (2), 1-methyl-2-pyridin-2-yl-1H-benzimidazole (3), 2-(4'-thiazolyl)benzimidazole (4), 1-methyl-2-(4'-thiazolyl)benzimidazole (5)) is reported, and their use as electroluminescent materials in light-emitting electrochemical cell (LEC) devices is investigated. [2][PF6] and [3][PF6] are orange emitters with intense unstructured emission around 590 nm in acetonitrile solution. [1][PF6], [4][PF6], and [5][PF6] are green weak emitters with structured emission bands peaking around 500 nm. The different photophysical properties are due to the effect that the chemical structure of the ancillary ligand has on the nature of the emitting triplet state. Whereas the benzimidazole unit stabilizes the LUMO and gives rise to a 3MLCT/3LLCT emitting triplet in [2][PF6] and [3][PF6], the presence of the thiazolyl ring produces the opposite effect in [4][PF6] and [5][PF6] and the emitting state has a predominant 3LC character. Complexes with 3MLCT/3LLCT emitting triplets give rise to LEC devices with luminance values 1 order higher than those of complexes with 3LC emitting states. Protecting the imidazole N-H bond with a methyl group, as in complexes [3][PF6] and [5][PF6], shows that the emissive properties become more stable. [3][PF6] leads to outstanding LECs with simultaneously high luminance (904 cd m-2), efficiency (9.15 cd A-1), and stability (lifetime over 2500 h).
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Affiliation(s)
- Marta Martínez-Alonso
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos , Plaza Misael Bañuelos s/n, 09001 Burgos, Spain
| | - Jesús Cerdá
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Cristina Momblona
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Antonio Pertegás
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - José M Junquera-Hernández
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Aránzazu Heras
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos , Plaza Misael Bañuelos s/n, 09001 Burgos, Spain
| | - Ana M Rodríguez
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Universidad de Castilla-La Mancha , Avda. Camilo J. Cela 10, 13071 Ciudad Real, Spain
| | - Gustavo Espino
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos , Plaza Misael Bañuelos s/n, 09001 Burgos, Spain
| | - Henk Bolink
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Enrique Ortí
- Instituto de Ciencia Molecular, Universidad de Valencia , Catedrático José Beltrán 2, 46980 Paterna, Spain
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10
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Hou H, Gan Y, Yin J, Jiang X. Polymerization-Induced Growth of Microprotuberance on the Photocuring Coating. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2027-2032. [PMID: 28186778 DOI: 10.1021/acs.langmuir.7b00067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Surface pattern on the nano- and microscale is of great interest due to its special optical effect, which might find potential application in optical devices such as LCD display, packaging of LED chip, and thin-film solar cell. We here developed a facile bottom-up approach to fabricate microprotuberance (MP) on surface by using curable resin via sequential photocuring at room temperature and thermal polymerization at high temperature. The curable resin is composed of random fluorinated polystyrene (PSF) as blinder and trimethylolpropane trimethacrylate (TMPTA) as cross-linker. The polymerization of TMPTA during the annealing process at high temperature induces phase separation between the PSF and TMPTA cross-linked network, resulting in the extrusion of PSF and the formation of protuberance on the surface. The formation mechanism of MP was studied in detail by investigating the effect of annealing time, temperature, thickness of film, and PSF on the size and morphology. MPs with size from one to tens of micrometers were fabricated through this one-pot strategy. Moreover, encapsulation of integrated GaN/InGaN-based LED chip by the cross-linked coating with MP can enhance the light extraction efficiency and light diffusion obviously.
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Affiliation(s)
- Honghao Hou
- School of Chemistry & Chemical Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China
| | - Yanchang Gan
- School of Chemistry & Chemical Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China
| | - Jie Yin
- School of Chemistry & Chemical Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China
| | - Xuesong Jiang
- School of Chemistry & Chemical Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University , Shanghai 200240, People's Republic of China
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11
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Jafari MJ, Liu J, Engquist I, Ederth T. Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells. ACS APPLIED MATERIALS & INTERFACES 2017; 9:2747-2757. [PMID: 28032741 DOI: 10.1021/acsami.6b14162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.
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Affiliation(s)
- Mohammad Javad Jafari
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University , Linköping SE-581 83, Sweden
| | - Jiang Liu
- Department of Science and Technology, Campus Norrköping, Linköping University , Norrköping SE-601 74, Sweden
| | - Isak Engquist
- Department of Science and Technology, Campus Norrköping, Linköping University , Norrköping SE-601 74, Sweden
| | - Thomas Ederth
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University , Linköping SE-581 83, Sweden
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12
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Light-Emitting Electrochemical Cells: A Review on Recent Progress. Top Curr Chem (Cham) 2016; 374:40. [PMID: 27573392 DOI: 10.1007/s41061-016-0040-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/26/2016] [Indexed: 10/21/2022]
Abstract
The light-emitting electrochemical cell (LEC) is an area-emitting device, which features a complex turn-on process that ends with the formation of a p-n junction doping structure within the active material. This in-situ doping transformation is attractive in that it promises to pave the way for an unprecedented low-cost fabrication of thin and light-weight devices that present efficient light emission at low applied voltage. In this review, we present recent insights regarding the operational mechanism, breakthroughs in the development of scalable and adaptable solution-based methods for cost-efficient fabrication, and successful efforts toward the realization of LEC devices with improved efficiency and stability.
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13
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Brunner F, Martínez-Sarti L, Keller S, Pertegás A, Prescimone A, Constable EC, Bolink HJ, Housecroft CE. Peripheral halo-functionalization in [Cu(N^N)(P^P)]+ emitters: influence on the performances of light-emitting electrochemical cells. Dalton Trans 2016; 45:15180-15192. [DOI: 10.1039/c6dt02665f] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Trends in the performance data of [Cu(N^N)(P^P)]+-based LECs in which N^N ligands bear peripheral F, Cl, Br or I substituents reveal that fluoro-groups are beneficial, but heavier halo-substituents lead to poor devices.
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Affiliation(s)
- Fabian Brunner
- Department of Chemistry
- University of Basel
- CH-4056 Basel
- Switzerland
| | | | - Sarah Keller
- Department of Chemistry
- University of Basel
- CH-4056 Basel
- Switzerland
| | - Antonio Pertegás
- Instituto de Ciencia Molecular
- Universidad de Valencia
- Paterna
- Spain
| | | | | | - Henk J. Bolink
- Instituto de Ciencia Molecular
- Universidad de Valencia
- Paterna
- Spain
- Fundació General de la Universitat de Valencia (FGUV)
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14
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Kerszulis JA, Amb CM, Dyer AL, Reynolds JR. Follow the Yellow Brick Road: Structural Optimization of Vibrant Yellow-to-Transmissive Electrochromic Conjugated Polymers. Macromolecules 2014. [DOI: 10.1021/ma501080u] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Justin A. Kerszulis
- School
of Chemistry and Biochemistry, School of Materials Science and Engineering,
Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Chad M. Amb
- The
George and Josephine Butler Polymer Laboratories, Department of Chemistry,
Center for Macromolecular Science and Engineering, University of Florida, PO Box 117200, Gainesville, Florida 32611, United States
| | - Aubrey L. Dyer
- School
of Chemistry and Biochemistry, School of Materials Science and Engineering,
Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - John R. Reynolds
- School
of Chemistry and Biochemistry, School of Materials Science and Engineering,
Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| |
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