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Siddiqui I, Kumar S, Tsai YF, Gautam P, Shahnawaz, Kesavan K, Lin JT, Khai L, Chou KH, Choudhury A, Grigalevicius S, Jou JH. Status and Challenges of Blue OLEDs: A Review. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2521. [PMID: 37764550 PMCID: PMC10536903 DOI: 10.3390/nano13182521] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023]
Abstract
Organic light-emitting diodes (OLEDs) have outperformed conventional display technologies in smartphones, smartwatches, tablets, and televisions while gradually growing to cover a sizable fraction of the solid-state lighting industry. Blue emission is a crucial chromatic component for realizing high-quality red, green, blue, and yellow (RGBY) and RGB white display technologies and solid-state lighting sources. For consumer products with desirable lifetimes and efficiency, deep blue emissions with much higher power efficiency and operation time are necessary prerequisites. This article reviews over 700 papers covering various factors, namely, the crucial role of blue emission for full-color displays and solid-state lighting, the performance status of blue OLEDs, and the systematic development of fluorescent, phosphorescent, and thermally activated delayed fluorescence blue emitters. In addition, various challenges concerning deep blue efficiency, lifetime, and approaches to realizing deeper blue emission and higher efficacy for blue OLED devices are also described.
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Affiliation(s)
- Iram Siddiqui
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Sudhir Kumar
- Institute for Chemical and Bioengineering, ETH Zürich, 8093 Zürich, Switzerland
| | - Yi-Fang Tsai
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Prakalp Gautam
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Shahnawaz
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Kiran Kesavan
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Jin-Ting Lin
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Luke Khai
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Kuo-Hsien Chou
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Abhijeet Choudhury
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Saulius Grigalevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, LT-50254 Kaunas, Lithuania
| | - Jwo-Huei Jou
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
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Wang L, Miao J, Zhang Y, Wu C, Huang H, Wang X, Yang C. Discrete Mononuclear Platinum(II) Complexes Realize High-Performance Red Phosphorescent OLEDs with EQEs of up to 31.8% and Superb Device Stability. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2303066. [PMID: 37327208 DOI: 10.1002/adma.202303066] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/14/2023] [Indexed: 06/18/2023]
Abstract
Designing mononuclear platinum(II) complexes that do not rely on intermolecular aggregation for high-performance red organic light-emitting diodes remains a formidable challenge. In this work, three robust red-emitting Pt(II) complexes are created by utilizing a rigid 4-coordination configuration, where the ligands are formed by linking electron-donor of triphenylamine (TPA) moieties with electron-acceptor of pyridine, isoquinoline, and/or δ-carboline units. The thermal stability, electrochemical, and photophysical properties of the complexes are thoroughly examined. The complexes display efficient red phosphorescence, with high photoluminescence quantum yields and short excited lifetimes. The OLEDs dope with these complexes exhibit high maximum external quantum efficiencies (EQEs) of up to 31.8% with minimal efficiency roll-off even at high brightness. Significantly, the devices demonstrate exceptional long operational lifetime, with a T90 lifetime of over 14000 h at initial luminance of 1000 cd m-2 , indicating the potential for these complexes to be practically utilizes.
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Affiliation(s)
- Lian Wang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Jingsheng Miao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Youming Zhang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
- Shenzhen Institute of Information Technology, Shenzhen, 518172, P. R. China
| | - Chengjun Wu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Hong Huang
- Shenzhen Institute of Information Technology, Shenzhen, 518172, P. R. China
| | - Xinzhong Wang
- Shenzhen Institute of Information Technology, Shenzhen, 518172, P. R. China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
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Host-Guest Doping Induced Excited State Energy Transfer for Efficient Room Temperature Phosphorescence Emission. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.12.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Kim SY, Kim JH, Lee S, Yun BS, Son HJ, Kang SO. Tuning the Photophysical Properties of Homoleptic Tris-Cyclometalated Ir(III) Complexes by Facile Modification of the Imidazo-Phenanthridine and Their Application to Phosphorescent Organic Light-Emitting Diodes. ACS OMEGA 2022; 7:17234-17244. [PMID: 35647420 PMCID: PMC9134233 DOI: 10.1021/acsomega.2c01155] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/29/2022] [Indexed: 05/07/2023]
Abstract
To explore the excited-state electronic structure of the blue-emitting Ir(dmp)3 dopant material (dmp = 3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridine), which is notable for durable blue phosphorescent organic light-emitting diode (PhOLED), a series of homoleptic dmp-based Ir(III) complexes (DMP-R, tris[3-(2,6-dimethylphenyl)-7-R-imidazo[1,2-f]phenanthridin-12-yl-κC 12,κN 1]iridium, R = H, CH3, F, and CF3) were prepared by introducing an electron-donating group (EDG; -CH3) or an electron-withdrawing group (EWG; -F and -CF3) at the 7-position of the imidazo-phenanthridine ligand. The photophysical analysis demonstrated that the alteration from EDG to EWGs led to redshifted structureless emission profiles, which were correlated with variations in the 3MLCT/3ILCT ratio in the T1 excited state. From electrochemical studies and density functional theory calculations, it turned out that the excited-state nature of the dmp-based Ir(III) complexes was significantly affected by the inductive effect of the 7-substituent of the cyclometalating dmp ligand. As a result of the lowest unoccupied molecular orbital energy stabilization by the EWGs that suppressed the non-radiative pathway from the emissive triplet excited state to the 3 d-d state, the F- and CF3-modified Ir(dmp)3 complexes (DMP-F and DMP-CF 3 ) showed quantum yields of 27-30% in the solution state, which were at least 4- or 5-fold higher than those shown by DMP-H and DMP-CH 3 . A PhOLED device based on DMP-CF 3 [CIE chromaticity (0.17, 0.39)], which demonstrated a distinct 3MLCT characteristic, exhibited better electroluminescent efficiencies with an external quantum efficiency of 13.5% than that based on DMP-CH 3 .
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Kuo H, Zhu Z, Lee C, Chen Y, Liu S, Chou P, Jen AK, Chi Y. Bis-Tridentate Iridium(III) Phosphors with Very High Photostability and Fabrication of Blue-Emitting OLEDs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1800846. [PMID: 30250813 PMCID: PMC6145234 DOI: 10.1002/advs.201800846] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/09/2018] [Indexed: 05/08/2023]
Abstract
Sky-blue and blue-emitting, carbazolyl functionalized, bis-tridentate Ir(III) phosphors Cz-1-Cz-3 with bright emission and short radiative lifetime are successfully synthesized in a one-pot manner. They exhibit very high photostability against UV-vis irradiation in degassed toluene, versus both green and true-blue-emitting reference compounds, i.e., fac-[Ir(ppy)3] and mer-[Ir(pmp)3]. Organic light-emitting diodes (OLEDs) based on Cz-2 exhibit maximum external quantum efficiency (EQE) of 21.6%, EQE of 15.1% at 100 cd m-2, and with CIE x,y coordinates of (0.17, 0.25). This study provides a conceptual solution to the exceedingly stable and efficient blue phosphor. It is promising that long lifespan blue OLED based on these emitters can be attained with further engineering of devices suitable for commercial application.
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Affiliation(s)
- Hsin‐Hung Kuo
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of MattersNational Tsing Hua UniversityHsinchu30013Taiwan
| | - Ze‐lin Zhu
- Center of Super‐Diamond and Advanced Films (COSDAF) and Department of ChemistryCity University of Hong KongHong Kong SAR
| | - Chun‐Sing Lee
- Center of Super‐Diamond and Advanced Films (COSDAF) and Department of ChemistryCity University of Hong KongHong Kong SAR
| | - Yi‐Kuang Chen
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of MattersNational Tsing Hua UniversityHsinchu30013Taiwan
| | - Shih‐Hung Liu
- Department of ChemistryNational Taiwan UniversityTaipei10617Taiwan
| | - Pi‐Tai Chou
- Department of ChemistryNational Taiwan UniversityTaipei10617Taiwan
| | - Alex K.‐Y. Jen
- Department of Materials Science and Engineering and Department of ChemistryCity University of Hong KongHong Kong SAR
| | - Yun Chi
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of MattersNational Tsing Hua UniversityHsinchu30013Taiwan
- Department of Materials Science and Engineering and Department of ChemistryCity University of Hong KongHong Kong SAR
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