Fluorene pendant-functionalization of poly(N-vinylcarbazole) as deep-blue fluorescent and host materials for polymer light-emitting diodes

• Published in: Chinese chemical letters Vol. 34; no. 8; pp. 108078 - 489
• Main Authors: Sun, Ning, Zou, Qin, Chen, Wenyu, Zheng, Yingying, Sun, Kai, Li, Chunbin, Han, Yamin, Bai, Lubing, Wei, Chuanxin, Lin, Jinyi, Yin, Chengrong, Wang, Jianguo, Huang, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2023; Shaanxi Institute of Flexible Electronics(SIFE),Northwestern Polytechnical University(NPU),Xi'an 710072,China; Centre for Molecular Systems and Organic Devices(CMSOD),Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials(IAM),Nanjing University of Posts and Telecommunications,Nanjing 210023,China; Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM),Nanjing Tech University(NanjingTech),Nanjing 211816,China; College of Chemistry and Chemical Engineering,Inner Mongolia Key Laboratory of Fine Organic Synthesis,Inner Mongolia University,Hohhot 010021,China%Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM),Nanjing Tech University(NanjingTech),Nanjing 211816,China%College of Chemistry and Chemical Engineering,Inner Mongolia Key Laboratory of Fine Organic Synthesis,Inner Mongolia University,Hohhot 010021,China%Centre for Molecular Systems and Organic Devices(CMSOD),Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials(IAM),Nanjing University of Posts and Telecommunications,Nanjing 210023,China%Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM),Nanjing Tech University(NanjingTech),Nanjing 211816,China
• Subjects: Deep-blue emission; Energy transfer; Fluorene; Poly(N-vinylcarbazole); Polymer light-emitting diodes; Fluorene; Polymer light-emitting diodes; Deep-blue emission; Energy transfer; Poly(N-vinylcarbazole)
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2022.108078

π-Electron coupling of pendant conjugated segment in π-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons, which is harmful to the performance and stability of deep-blue polymer light-emitting diodes (PLEDs). Herein, considerate of “defect” carbazole (Cz) electromers in poly(N-vinylcarbazole) (PVK), a series of fluorene units are introduced into pendant segments (PVCz-DMeF, PVCz-FMeNPh and PVCz-DFMeNPh) to suppress the strong π-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs. Compared to PVCz-FMeNPh and PVCz-DFMeNPh, PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission, completely similar to its single pendant chromophore, confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments. Therefore, PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity (0.17, 0.08), associated with extremely weak defect emission at 600∼700 nm (induced by carbazole electromers). Finally, PLEDs based on PVCz-DMeF/F8BT blended films (1:1) also present the high maximum luminance (Lmax) of 6261 cd/m2 and current efficiency (CEmax) of 2.03 cd/A, confirmed slightly trapped sites formation. Therefore, precisely control the arrangement and packing model of pendant units in π-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.
The pendant steric functionalization of π-stacked semiconducting polymers is an effective strategy to precisely control their excitonic behavior and photophysical processing toward the optoelectronic devices.
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