-
Charge balances can influence the emission efficiency of exciplex-based organic light-emitting diodes (OLEDs), but so far, the physical mechanism behind this phenomenon is not fully understood. Here, organic magnetic field effects (OMFEs) including magneto-conductance (MC), magneto-electroluminescence (MEL), and magneto-efficiency (Mη) are used as fingerprint probing tools to study physical mechanism of influence of charge balanceon the emission efficiency of exciplex-based OLEDs. Specifically, low- and high-field effects of MC traces [MCL (|B| ≤ 10 mT) and MCH (10 < |B| ≤ 300 mT)] from the unbalanced device are separately attributed to the magnetic field (B)-mediated intersystem crossing (ISC) process and the B-mediated triplet-charge annihilation (TCA) process between triplet exciplex states and excessive charge carriers, whereas those from the balanced device are respectively attributed to the B-mediated reverse intersystem crossing (RISC) process and the balanced carrier injection. As the injection current decreases from 200 to 25 μA, low-field effects of MEL traces (MELL) form the unbalanced device always reflect the B-mediated ISC process, but those from the balanced device exhibit a conversion from ISC process to RISC process. Furthermore, although low-field effects of Mη traces (MηL) from unbalanced device and balanced device are attributed to the B-mediated ISC process, MηL value in the balanced device is approximately one-fourth of that in the unbalanced device. These different MC, MEL, and Mη traces reveal that the balanced carrier injection can increase the number of triplet exciplex states via weakening the TCA process, which leads to the enhanced RISC process. Because RISC can convert dark triplet exciplex states into bright singlet exciplex states, the emission efficiency of the balanced device is higher than that of the unbalanced one. Obviously, in this work OMFEs are used to provide a new physical mechanism for charge balance that influences the emission efficiency of exciplex-based OLEDs.
-
Keywords:
- organic light-emitting diodes /
- magneto-conductance /
- magneto-electroluminescence /
- magneto-efficiency
-
图 1 (a), (b)能级排布图; (c)有机材料的分子结构图; (d)有机半导体薄膜的PL谱和器件的EL谱; (e), (f)电流随电压的变化关系和EL强度随电流的变化关系
Figure 1. (a), (b) Energy-level diagrams; (c) molecular structures of organic materials; (d) PL spectra of organic semiconductor films and EL spectra of devices; (e), (f) current as a function of voltage and EL intensity as a function of current.
图 2 (a), (b)器件1和器件2中MC曲线的电流依赖关系
Figure 2. (a), (b) Current-dependent MC traces of devices 1 and 2.
图 5 (a), (b)器件1和器件2中PP态和EX态的形成和演变通道
Figure 5. (a), (b) Formation and evolution channels of PP and EX states in devices 1 and 2.
图 3 (a), (b) 器件1和器件2中MEL曲线的电流依赖关系
Figure 3. (a), (b) Current-dependent MEL traces of devices 1 and 2.
图 4 (a), (b)器件1和器件2中Mη曲线的电流依赖关系
Figure 4. (a), (b) Current-dependent Mη traces of devices 1 and 2.
图 6 器件1、器件2和器件3的电流效率-电压特性曲线
Figure 6. Current efficiency-voltage characteristics of devices 1, 2, and 3.
图 7 器件3的能级结构、光电特性和有机磁效应 (a)能级结构; (b) EL谱; (c)亮度-电流特性; (d)—(f) MC, MEL和Mη曲线的电流依赖关系
Figure 7. Energy-level structure, photoelectric properties, and OMFEs of device 3: (a) Energy-level structure; (b) EL spectrum; (c) brightness-current characteristic; (d)–(f) current-dependent MC, MEL, and Mη traces.
-
[1] Gu J N, Tang Z Y, Guo H Q, Chen Y, Xiao J, Chen Z J, Xiao L X 2022 J. Mater. Chem. C 10 4521
Google Scholar
[2] Amin N R A, Kesavan K K, Biring S, Lee C C, Yeh T H, Ko T Y, Liu S W, Wong K T, 2020 ACS Appl. Electron. Mater. 2 1011
Google Scholar
[3] Li W S, Zhang X W, Zhang Y, Xu K, Xu J W, Wang H, Li H O, Guo J, Mo J H, Yang P Z 2018 Synth. Met. 245 111
Google Scholar
[4] Ying S A, Yuan J K, Zhang S, Sun Q, Dai Y F, Qiao X F, Yang D Z, Chen J S, Ma D G 2019 J. Mater. Chem. C 7 7114
Google Scholar
[5] Hung W Y, Chiang P Y, Lin S W, Tang W C, Chen Y T, Liu S H, Chou P T, Hung Y T, Wong K T 2016 ACS Appl. Mater. Interfaces 8 4811
Google Scholar
[6] Sheng R, Li A S, Zhang F J, Song J, Duan Y, Chen P 2020 Adv. Optical Mater. 8 1901247
Google Scholar
[7] 宁亚茹, 赵茜, 汤仙童, 陈敬, 吴凤娇, 贾伟尧, 陈晓莉, 熊祖洪 2022 物理学报 71 087201
Google Scholar
Ning Y R, Zhao X, Tang X T, Chen J, Wu F J, Jia W Y, Chen X L, Xiong Z H 2022 Acta Phys. Sin. 71 087201
Google Scholar
[8] Liu C H, Du H T, Yu Y, Chen Z, Ren J F, Fan J H, Liu Q, Han S H, Pang Z Y 2024 Org. Electron. 128 107025
Google Scholar
[9] Jin P F, Zhou Z Y, Wang H, Hao J J, Chen R, Wang J Y, Zhang C 2022 J. Phys. Chem. Lett. 13 2516
Google Scholar
[10] Wei F X, Chen J, Zhao X, Wu Y T, Wang H Y, Chen X L, Xiong Z H 2023 Adv. Sci. 10 2303192
Google Scholar
[11] Niu L B, Zhang Y, Chen L J, Zhang Q M, Guan Y X 2020 Org. Electron. 87 105971
Google Scholar
[12] 赵茜, 陈敬, 彭腾, 刘俊宏, 汪波, 陈晓莉, 熊祖洪 2023 物理学报 72 167201
Google Scholar
Zhao X, Chen J, Peng T, Liu J H, Wang B, Chen X L, Xiong Z H 2023 Acta Phys. Sin. 72 167201
Google Scholar
[13] Wu F J, Zhao X, Zhu H Q, Tang X T, Ning Y R, Chen J, Chen X L, Xiong Z H 2022 ACS Photonics 9 2713
Google Scholar
[14] Shao M, Yan L, Li M X, Ilia I, Hu B 2013 J. Mater. Chem. C 1 1330
Google Scholar
[15] Zhao X, Tang X T, Zhu H Q, Ma C H, Wang Y, Ye S N, Tu L Y, Xiong Z H 2021 ACS Appl. Electron. Mater. 3 3034
Google Scholar
[16] Hsiao C H, Liu S W, Chen C T, Lee J H 2010 Org. Electron. 11 1500
Google Scholar
[17] Hung W Y, Fang G C, Lin S W, Cheng S H, Wong K T, Kuo T Y, Chou P T 2014 Sci. Rep. 4 5161
Google Scholar
[18] Shen D, Chen W C, Lo M F, Lee C S 2021 Mater. Today Energy 20 100644
Google Scholar
[19] Zhang Q, Liu X J, Jiao F, Braun S, Jafari M J, Crispin X, Ederth T, Fahlman M 2017 J. Mater. Chem. C 5 275
Google Scholar
[20] Hua J, Li J X, Zhan Z L, Chai Y, Cheng Z Y, Li P D, Dong H, Wang J 2022 RSC Adv. 12 21932
Google Scholar
[21] Miao Y Q, Wang G L, Yin M N, Guo Y Y, Zhao B, Wang H 2023 Chem. Eng. J. 461 141921
Google Scholar
[22] Sheng Y, Nguyen T D, Veeraraghavan G, Mermer Ö, Wohlgenannt M, Qiu S, Scherf U 2006 Phys. Rev. B 74 045213
Google Scholar
[23] Wang Y F, Tiras K S, Harmon N J, Wohlgenannt M, Flatté M E 2016 Phys. Rev. X 6 011011
[24] Zhang T T, Holford D F, Gu H, Kreouzis T, Zhang S J, Gillin W P 2016 Appl. Phys. Lett. 108 023303
Google Scholar
[25] Hu Y Q, Tang X T, Pan R H, Deng J Q, Zhu H Q, Xiong Z H 2019 Phys. Chem. Chem. Phys. 21 17673
Google Scholar
[26] 汤仙童, 潘睿亨, 熊祖洪 2023 科学通报 68 2401
Tang X T, Pan R H, Xiong Z H 2023 Chin. Sci. Bull. 68 2401
[27] Crooker S A, Liu F L, Kelley M R, Martinez N J D, Nie W Y, Mohite A D, Nayyar I H, Tretiak S, Smith D L, Ruden P P 2014 Appl. Phys. Lett. 105 153304
Google Scholar
[28] Liu F L, Kelley M R, Crooker S A, Nie W Y, Mohite A D, Ruden P P, Smith D L 2014 Phys. Rev. B 90 235314
Google Scholar
[29] Chen P, Peng Q M, Yao L, Gao N, Li F 2013 Appl. Phys. Lett. 102 063301
Google Scholar
[30] Peng Q M, Li A W, Fan Y X, Chen P, Li F 2014 J. Mater. Chem. C 2 6264
Google Scholar
[31] Janssen P, Cox M, Wouters S H W, Kemerink M, Wienk M M, Koopmans B 2013 Nat. Commun. 4 2286
Google Scholar
[32] Yuan P S, Qiao X F, Yan D H, Ma D G 2018 J. Mater. Chem. C 6 5721
Google Scholar
[33] Zhang T Y, Chu B, Li W L, Su Z S, Peng Q M, Zhao B, Luo Y S, Jin F M, Yan X W, Gao Y, Wu H R, Zhang F, Fan D, Wang J B 2014 ACS Appl. Mater. Interfaces 6 11907
Google Scholar
[34] 吴雨廷, 朱洪强, 魏福贤, 王辉耀, 陈敬, 宁亚茹, 吴凤娇, 陈晓莉, 熊祖洪 2022 物理学报 71 227201
Google Scholar
Wu Y T, Zhu H Q, Wei F X, Wang H Y, Chen J, Ning Y R, Wu F J, Chen X L, Xiong Z H 2022 Acta Phys. Sin. 71 227201
Google Scholar
[35] Kim K H, Yoo S J, Kim J J 2016 Chem. Mater. 28 1936
Google Scholar
[36] Zhu H Q, Jia W Y, Chen L X, Tang X T, Hu Y Q, Pan R H, Deng J Q, Xiong Z H 2019 J. Mater. Chem. C 7 553
Google Scholar
DownLoad:
Metrics
- Abstract views: 292
- PDF Downloads: 8
- Cited By: 0
