title: Highly Efficient Nondoped Green Organic Light-Emitting Diodes with Combination of High Photoluminescence and High Exciton Utilization.
abstract: Photoluminescence (PL) efficiency and exciton utilization efficiency are two key parameters to harvest high-efficiency electroluminescence (EL) in organic light-emitting diodes (OLEDs). But it is not easy to simultaneously combine these two characteristics (high PL efficiency and high exciton utilization) into a fluorescent material. In this work, an efficient combination was achieved through two concepts of hybridized local and charge-transfer (CT) state (HLCT) and "hot exciton", in which the former is responsible for high PL efficiency while the latter contributes to high exciton utilization. On the basis of a tiny chemical modification in TPA-BZP, a green-light donor-acceptor molecule, we designed and synthesized CzP-BZP with this efficeient combination of high PL efficiency of η(PL) = 75% in the solid state and maximal exciton utilization efficiency up to 48% (especially, the internal quantum efficiency of η(IQE) = 35% substantially exceed 25% of spin statistics limit) in OLED. The nondoped OLED of CzP-BZP exhibited an excellent performance: a green emission with a CIE coordinate of (0.34, 0.60), a maximum current efficiency of 23.99 cd A(-1), and a maximum external quantum efficiency (EQE, η(EQE)) of 6.95%. This combined HLCT state and "hot exciton" strategy should be a practical way to design next-generation, low-cost, high-efficiency fluorescent OLED materials.
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Chu
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology , Guangzhou, 510640, People's Republic of China.
authors.forename: Xianglong
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Yuyu
authors.initials: Y
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Shitong
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Liang
authors.initials: L
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Bai
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Weijun
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, Jilin University , 2699 Qianjin Avenue, Changchun, 130012, People's Republic of China.
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology , Guangzhou, 510640, People's Republic of China.
authors.forename: Shijian
authors.initials: S
authors.lastname: Su
authors.affiliation: State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology , Guangzhou, 510640, People's Republic of China.
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Ma
keywords: OLEDs; exciton utilization; hot exciton; hybridized local and charge-transfer state (HLCT); photoluminescence efficiency