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Lebedeva IV, Jornet-Somoza J. Optical properties and exciton transfer between N-heterocyclic carbene iridium(III) complexes for blue light-emitting diode applications from first principles. J Chem Phys 2024; 160:084107. [PMID: 38391015 DOI: 10.1063/5.0193161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/05/2024] [Indexed: 02/24/2024] Open
Abstract
N-heterocyclic carbene (NHC) iridium(III) complexes are considered as promising candidates for blue emitters in organic light-emitting diodes. They can play the roles of the emitter as well as of electron and hole transporters in the same emission layer. We investigate optical transitions in such complexes with account of geometry and electronic structure changes upon excitation or charging and exciton transfer between the complexes from first principles. It is shown that excitation of NHC iridium complexes is accompanied by a large reorganization energy ∼0.7 eV and a significant loss in the oscillator strength, which should lead to low exciton diffusion. Calculations with account of spin-orbit coupling reveal a small singlet-triplet splitting ∼0.1 eV, whereas the oscillator strength for triplet excitations is found to be an order of magnitude smaller than for the singlet ones. The contributions of the Förster and Dexter mechanisms are analyzed via the explicit integration of transition densities. It is shown that for typical distances between emitter complexes in the emission layer, the contribution of the Dexter mechanism should be negligible compared to the Förster mechanism. At the same time, the ideal dipole approximation, although giving the correct order of the exciton coupling, fails to reproduce the result taking into account spatial distribution of the transition density. For charged NHC complexes, we find a number of optical transitions close to the emission peak of the blue emitter with high exciton transfer rates that can be responsible for exciton-polaron quenching. The nature of these transitions is analyzed.
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Affiliation(s)
- Irina V Lebedeva
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Joaquim Jornet-Somoza
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
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Yan J, Qu ZH, Zhou DY, Yiu SM, Qin Y, Zhou X, Liao LS, Chi Y. Bis-tridentate Ir(III) Phosphors and Blue Hyperphosphorescence with Suppressed Efficiency Roll-Off at High Brightness. ACS APPLIED MATERIALS & INTERFACES 2024; 16:3809-3818. [PMID: 38211320 DOI: 10.1021/acsami.3c16260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Narrowband blue emitters are indispensable in achieving ultrahigh-definition OLED displays that satisfy the stringent BT 2020 standard. Hereby, a series of bis-tridentate Ir(III) complexes bearing electron-deficient imidazo[4,5-b]pyridin-2-ylidene carbene coordination fragments and 2,6-diaryloxy pyridine ancillary groups were designed and synthesized. They exhibited deep blue emission with quantum yields of up to 89% and a radiative lifetime of 0.71 μs in the DPEPO host matrix, indicating both the high efficiency and excellent energy transfer process from the host to dopant. The OLED based on Irtb1 showed an emission at 468 nm with a maximum external quantum efficiency (EQE) of 22.7%. Moreover, the hyper-OLED with Irtb1 as a sensitizer for transferring energy to terminal emitter v-DABNA exhibited a narrowband blue emission at 472 nm and full width at half-maximum (FWHM) of 24 nm, a maximum EQE of 23.5%, and EQEs of 19.7, 16.1, and 12.9% at a practical brightness of 100, 1000, and 5000 cd/m2, respectively.
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Affiliation(s)
- Jie Yan
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Zhi-Hao Qu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Dong-Ying Zhou
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Shek-Man Yiu
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Yanyan Qin
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
| | - Xiuwen Zhou
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Liang-Sheng Liao
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215006, China
| | - Yun Chi
- Department of Chemistry, Department of Materials Science and Engineering, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong
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Tang Y, Mak CH, Zhang J, Jia G, Cheng KC, Song H, Yuan M, Zhao S, Kai JJ, Colmenares JC, Hsu HY. Unravelling the Interfacial Dynamics of Bandgap Funneling in Bismuth-Based Halide Perovskites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207835. [PMID: 36245308 DOI: 10.1002/adma.202207835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/25/2022] [Indexed: 06/16/2023]
Abstract
An environmentally friendly mixed-halide perovskite MA3 Bi2 Cl9- x Ix with a bandgap funnel structure has been developed. However, the dynamic interfacial interactions of bandgap funneling in MA3 Bi2 Cl9- x Ix perovskites in the photoelectrochemical (PEC) system remain ambiguous. In light of this, single- and mixed-halide lead-free bismuth-based hybrid perovskites-MA3 Bi2 Cl9- y Iy and MA3 Bi2 I9 (named MBCl-I and MBI)-in the presence and absence of the bandgap funnel structure, respectively, are prepared. Using temperature-dependent transient photoluminescence and electrochemical voltammetric techniques, the photophysical and (photo)electrochemical phenomena of solid-solid and solid-liquid interfaces for MBCl-I and MBI halide perovskites are therefore confirmed. Concerning the mixed-halide hybrid perovskites MBCl-I with a bandgap funnel structure, stronger electronic coupling arising from an enhanced overlap of electronic wavefunctions results in more efficient exciton transport. Besides, MBCl-I's effective diffusion coefficient and electron-transfer rate demonstrate efficient heterogeneous charge transfer at the solid-liquid interface, generating improved photoelectrochemical hydrogen production. Consequently, this combination of photophysical and electrochemical techniques opens up an avenue to explore the intrinsic and interfacial properties of semiconductor materials for elucidating the correlation between material characterization and device performance.
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Affiliation(s)
- Yunqi Tang
- School of Energy and Environment, Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
- Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, P. R. China
| | - Chun Hong Mak
- School of Energy and Environment, Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
- Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, P. R. China
| | - Jun Zhang
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
| | - Guohua Jia
- Curtin Institute of Functional Molecules and Interfaces, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - Kuan-Chen Cheng
- Graduate Institute of Food Science Technology, National Taiwan University, Taipei, 10617, Taiwan
- Institute of Biotechnology, National Taiwan University, Taipei, 10617, Taiwan
- Department of Optometry, Asia University, 500 Lioufeng Rd., Wufeng, Taichung, 41354, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Haisheng Song
- Wuhan National Laboratory for Optoelectronics (WNLO) and School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Mingjian Yuan
- Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (RECAST), College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Shijun Zhao
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
| | - Ji-Jung Kai
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
| | | | - Hsien-Yi Hsu
- School of Energy and Environment, Department of Materials Science and Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong, China
- Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, P. R. China
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Nandy A, Mukherjee S. A Bioinspired Light Harvesting System in Aqueous Medium: Highly Efficient Energy Transfer through the Self Assembly of β-Sheet Nanostructures of Poly-d-Lysine. J Phys Chem Lett 2022; 13:6701-6710. [PMID: 35848986 DOI: 10.1021/acs.jpclett.2c01309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Nature has beautifully assembled its light harvesting pigments within protein scaffolds, which ensures a very high energy transfer. Designing a highly efficient artificial bioinspired light harvesting system (LHS) thus requires the nanoscale spatial orientation and electronic control of the associated chromophores. Although DNA has been used as a scaffold to organize chromophores, proteins or polypeptides, however, are very rarely explored. Here, we have developed a highly efficient, artificial, bioinspired LHS using polypeptide (poly-d-lysine, PDL) nanostructures making use of their β-sheet structure in an aqueous alkaline medium. The chromophores used herein are compatible for an energy transfer process and are nonfluorescent in an aqueous medium but exhibit high fluorescence intensity when bound to the nanostructure of PDL. The close proximity of the chromophores results in an energy transfer efficiency of ∼92% besides generating white light emission at a particular molar ratio between the chromophores.
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Affiliation(s)
- Atanu Nandy
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
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Germino JC, Duarte LGTA, Mendes RA, Faleiros MM, de Morais A, de Freitas JN, Pereira L, Atvars TDZ. All-Solution Processed Single-Layer WOLEDs Using [Pt(salicylidenes)] as Guests in a PFO Matrix. NANOMATERIALS 2022; 12:nano12142497. [PMID: 35889721 PMCID: PMC9316125 DOI: 10.3390/nano12142497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/06/2022] [Accepted: 07/12/2022] [Indexed: 02/01/2023]
Abstract
Herein, we report the synthesis and characterization of two Pt(II) coordination compounds, the new platinum(II)[N,N′-bis(salicylidene)-3,4-diaminobenzophenone)] ([Pt(sal-3,4-ben)]) and the already well-known platinum(II)[N,N′-bis(salicylidene)-o-phenylenediamine] ([Pt(salophen)]), along with their application as guests in a poly [9,9-dioctylfluorenyl-2,7-diyl] (PFO) conjugated polymer in all-solution processed single-layer white organic light-emitting diodes. Completely different performances were achieved: 2.2% and 15.3% of external quantum efficiencies; 2.8 cd A−1 and 12.1 cd A−1 of current efficiencies; and 3103 cd m−2 and 6224 cd m−2 of luminance for the [Pt(salophen)] and [Pt(sal-3,4-ben)] complexes, respectively. The Commission Internationale de l’Eclairage (CIE 1931) chromaticity color coordinates are (0.33, 0.33) for both 0.1% mol/mol Pt(II):PFO composites at between approximately 3.2 and 8 V. The optoelectronic properties of doped and neat PFO films have been investigated, using steady-state and time-resolved photoluminescence. Theoretical calculations at the level of relativistic density functional theory explained these results, based on the presence of the Pt(II) central ion’s phosphorescence emission, considering spin-orbit coupling relationships. The overall results are explained, taking into account the active layer morphological properties, along with the device’s electric balance and the emitter’s efficiencies, according to deep-trap space-charge models. Considering the very simple structure of the device and the ease of synthesis of such compounds, the developed framework can offer a good trade-off for solution-deposited white organic light-emitting diodes (WOLEDs), with further applications in the field of lighting and signage.
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Affiliation(s)
- José Carlos Germino
- Chemistry Institute, University of Campinas—UNICAMP, Campinas 13083-862, Brazil; (L.G.T.A.D.); (M.M.F.); (T.D.Z.A.)
- Department of Physics and i3N—Institute for Nanostructures, Nanomodelling and Nanofabrication, University of Aveiro, 3810-193 Aveiro, Portugal
- Correspondence: (J.C.G.); (L.P.)
| | | | - Rodrigo Araújo Mendes
- São Carlos Institute of Chemistry, University of São Paulo—USP, São Carlos 13566-590, Brazil;
| | - Marcelo Meira Faleiros
- Chemistry Institute, University of Campinas—UNICAMP, Campinas 13083-862, Brazil; (L.G.T.A.D.); (M.M.F.); (T.D.Z.A.)
| | - Andreia de Morais
- Center for Information Technology Renato Archer—CTI, Campinas 13069-901, Brazil; (A.d.M.); (J.N.d.F.)
| | - Jilian Nei de Freitas
- Center for Information Technology Renato Archer—CTI, Campinas 13069-901, Brazil; (A.d.M.); (J.N.d.F.)
| | - Luiz Pereira
- Department of Physics and i3N—Institute for Nanostructures, Nanomodelling and Nanofabrication, University of Aveiro, 3810-193 Aveiro, Portugal
- Correspondence: (J.C.G.); (L.P.)
| | - Teresa Dib Zambon Atvars
- Chemistry Institute, University of Campinas—UNICAMP, Campinas 13083-862, Brazil; (L.G.T.A.D.); (M.M.F.); (T.D.Z.A.)
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Pei Z, Wei HY, Liu YC. Exciton Up-Conversion by Well-Distributed Carbon Quantum Dots in Luminescent Materials for an Efficient Organic Light-Emitting Diode. NANOMATERIALS 2022; 12:nano12071174. [PMID: 35407292 PMCID: PMC9000295 DOI: 10.3390/nano12071174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/21/2022] [Accepted: 03/28/2022] [Indexed: 11/16/2022]
Abstract
In this work, we proposed an efficient and straightforward up-conversion process to enhance the external quantum efficiency in a red-emission organic light-emitting diode (OLED). The carbon quantum dots in the luminescent materials initiated the up-conversion by doping the (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) in an amount of 0.001 wt. %, and the external quantum efficiency (EQE) increased from approximately 80% to 9.27% without spectrum change. The time-resolved photoluminescence was applied to understand the mechanism of EQE enhancement in the PCBM-doped OLED. Two decay-time constants fit the TRPL. After PCBM doping, the extended PL intensity indicated increased time constants. The time constants increased from 1.06 and 4.02 ns of the reference sample to 3.48 and 11.29 ns of the PCBM-doped material, respectively. The nonradiative energy transfer (NRET) mechanism was proposed responsible for the decay-time enhancement. The excitons in the PCBM, either by excitation or injection, will transfer to the phosphorescent material nonradiatively. As the PCBM has lower energy levels than the luminous material for electrons, the backward exciton transfer is a kind of up-conversion. With the increased amounts of excitons in the luminescent material, the luminescent external quantum efficiency and the decay-time increased. This up-conversion method is not limited to the red-emission OLED; it could also be applied to blue or green emission.
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Affiliation(s)
- Zingway Pei
- Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (H.-Y.W.); (Y.-C.L.)
- Innovation and Development Center of Sustainable Agriculture (IDCSA), National Chung Hsing University, Taichung 40227, Taiwan
- i-Center for Advanced Science and Technology (i-CAST), National Chung Hsing University, Taichung 40227, Taiwan
- Correspondence: ; Tel.: +886-4-22851549
| | - Han-Yun Wei
- Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (H.-Y.W.); (Y.-C.L.)
| | - Yi-Chun Liu
- Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan; (H.-Y.W.); (Y.-C.L.)
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