Development of Materials for Blue Organic Light Emitting Devices

Sarma, Monima; Wong, Ken‐Tsung

doi:10.1002/tcr.201800156

Cited by 24 publications

(21 citation statements)

References 76 publications

(177 reference statements)

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“…In comparison to unipolar host materials, bipolar host materials promote balanced charge flux and broaden the exciton recombination. 20,21,24 However, the construction of bipolar host molecules with spatially separated donor and acceptor moieties allows the formation of an intramolecular charge transfer (ICT) state, which may exhibit a twisted structure resulting in the excited state energy being consumed by the rotary motion of the molecule. [25][26][27] This results in quenching of the fluorescence and low emission quantum yield.…”

Section: Introductionmentioning

confidence: 99%

Protonation-induced fluorescence modulation of carbazole-based emitters

et al. 2022

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Section: Introductionmentioning

confidence: 99%

Protonation-induced fluorescence modulation of carbazole-based emitters

et al. 2022

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“…The fabricated OLED device with TFDPA as emitter showed deep blue luminescence as well as low turn-on voltage (2.5 V, Table 1). [53] Besides, they reported a couple of bi(9,9′-diarylfluorene) derivatives, T2, TB2, and TST (4, 5, and 6), which exhibited highly efficient ultraviolet (UV) emission (Scheme 4). [44,53,54] Additionally, these materials possess high thermal stability, rendering them to form homogeneous amorphous films via thermal evaporation.…”

Section: Diarylfluorene Fluorescent Small Moleculesmentioning

confidence: 99%

“…[53] Besides, they reported a couple of bi(9,9′-diarylfluorene) derivatives, T2, TB2, and TST (4, 5, and 6), which exhibited highly efficient ultraviolet (UV) emission (Scheme 4). [44,53,54] Additionally, these materials possess high thermal stability, rendering them to form homogeneous amorphous films via thermal evaporation. The OLED devices using the bifluorenes as emitters achieved external quantum efficiency (EQE) of 2.7-3.6% (Table 1).…”

Section: Diarylfluorene Fluorescent Small Moleculesmentioning

confidence: 99%

Diarylfluorene‐Based Organic Semiconductor Materials toward Optoelectronic Applications

Han

Bai

Lin

et al. 2021

Adv Funct Materials

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reorganizing these two types of π orbitals, thus endowing the active films with significantly different optoelectronic property. In order to design high-performance and stable conjugated molecules, some basic principles should be followed, such as electronic structure, conformation and topology, steric hindrance, as well as supramolecular interaction, which also called four fundamental nodes proposed by Huang group. [8] Particularly, steric hindrance design is an effective strategy to enhance device performance and stability via adjusting the spatial arrangement of active molecular bricks, the morphology of films, and the fine optoelectronic properties. [9,10] The sterically hindered groups are capable to rotate the dihedral angles of the adjacent monomer units, which can inhibit interchain interactions and further reduce aggregation. In addition, the rigid bulks are favorable for improving the morphological and emission spectral stability of light-emitting conjugated polymers in solid state. Besides, beyond the intrinsic electronic structures, molecular conformation and topology is a crucial for precisely tuning the physical process, controlling film morphology, device performance, and stability.Similar to the industrial manufacturing, modular production of conjugated materials enable them to present a precise electron-structure tunability, controllable structural modification, and low-cost large-scale preparation, similar to Lego building block. In the last decades, amounts of building blocks, such as fluorene, carbazole (Cz), thiophene (Th), and benzothiadiazole, have been employed to design various conjugated molecules for specific applications. [11][12][13][14][15] Among these synthons, fluorene-based bulks have been widely reported to construct high performance organic semiconductors for efficient optoelectronic devices, owing to their easy chemical modification, stable thermodynamic property, high fluorescence quantum yield, and appropriate charge transport capability. [16][17][18][19] Nevertheless, the conventional fluorene units suffer from poor color purity and luminous stability due to significantly interchain aggregation and photo-/electro-oxidation of the alkyl pendant groups at C9 position, which restricted their actual development. [20] The appearance of diarylfluorene structure provides a broader space for the design and preparation of blue emitters with higher purity and efficiency. In 1905, the simplest diarylfluorene (9,9′-diphenylfluorene) was synthesized by Ullmann and Wurstemberger for the first time. [21] As a most promise and popular alternative, diarylfluorene is a non-planar architecture

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“…Since the development of multi-layer organic light-emitting diodes (OLEDs) in 1987 [1], the device performance has been improved tremendously over the past decades. Owing to the merits of organic materials and improvements of their efficiencies, the application of OLEDs is widespread and anticipated to be expanded even further [2,3]. Despite the advantages compared with inorganic counterparts, however, the utilization of OLEDs is sometimes limited by their reliabilities.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Transient Degradation Behaviors of Organic Light-Emitting Diodes under Electrical Stress

et al. 2021

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Despite the wide application of organic light-emitting diodes (OLEDs), the performance of OLED devices is sometimes limited by their reliabilities. In this paper, we report the transient degradation behaviors of fluorescent blue OLEDs, where both the current and luminance initially increase under electrical stress within a short stress time. We analyze the degradation mechanism in terms of the carrier recombination and transport. From the comprehensive analyses of electrical and optical characteristics, it is suggested that the electron transport is responsible for the initial transient behavior of the device.

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Development of Materials for Blue Organic Light Emitting Devices

Cited by 24 publications

References 76 publications

Protonation-induced fluorescence modulation of carbazole-based emitters

Protonation-induced fluorescence modulation of carbazole-based emitters

Diarylfluorene‐Based Organic Semiconductor Materials toward Optoelectronic Applications

Analysis of Transient Degradation Behaviors of Organic Light-Emitting Diodes under Electrical Stress

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