Enhanced proportion of radiative excitons in non-doped electro-fluorescence generated from an imidazole derivative with an orthogonal donor–acceptor structure

Zhang, Shi‐Tong; Li, Weijun; Yao, Liang; Pan, Yuyu; Shen, Fangzhong; Xiao, Ran; Yang, Bing; Ma, Yuguang

doi:10.1039/c3cc47130f

Cited by 207 publications

(93 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the host‐guest system subsequently requires simultaneously depositing two different materials by controlling the evaporation speed and ratio of each material. The introduction of the non‐doped device configuration can simplify the evaporation process and lower the cost in the industrial production, and hence is much more favorable than the co‐deposition procedure . The non‐radiative process, in non‐doped devices, can be suppressed by either largely twisted molecular conformation or through interference with the molecular stacking; one of the major causes of non‐radiative quenching.…”

Section: Tadf Molecular Design Towards Efficient Oleds With Superior mentioning

confidence: 99%

“…The introduction of the non-doped device configurationc an simplify the evaporation process and lower the cost in the industrial production,a nd hence is much more favorable than the codeposition procedure. [62] The non-radiative process, in nondopedd evices,c an be suppressedb ye ither largely twisted molecular conformation or throughi nterference with the molecular stacking;o ne of the major causes of non-radiative quenching. Up to now,t he mostc ommonly adopted EWGs that can potentially induce non-doped TADF are sulfone, [14b] triazine, [14a] benzimidazole, [20f] andc arbonyl-containing groups, [63] etc (Figure 13).…”

Section: Design Of Tadf Molecules With Non-doped Capabilities In Tadfmentioning

confidence: 99%

See 1 more Smart Citation

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Liang

Zheng

2019

Chemistry A European J

194

123

View full text Add to dashboard Cite

Thermally activated delayed fluorescence (TADF) is one of the most intriguing and promising discoveries towards realization of highly‐efficient organic light emitting diodes (OLED) utilizing small molecules as emitters. It has the capability of manifesting all excitons generated during the electroluminescent processes, consequently achieving 100 % of internal quantum efficiency. Since the report of the first efficient OLED based on a TADF small molecule in 2012 by Adachi et al., the quest for optimal TADF materials for OLED application has never stopped. Various TADF molecules bearing different design concepts and strategies have been designed and produced, with the aim to boost the overall performances of corresponding OLEDs. In this minireview, the general principles of TADF molecular design based on three basic categories of TADF species: twisted intramolecular charge transfer (TICT), through‐space charge transfer (TSCT) and multi‐resonance induced TADF (MR‐TADF) are discussed in detail. Several key aspects with respect to each category, as well as some effective methods to enhance the efficiency of TADF materials and corresponding OLEDs from the molecular engineering perspectives, are summarized and discussed to exhibit a general landscape of TADF molecular design to a wide variety of scientific researchers within this particular disciplinary area.

show abstract

Section: Tadf Molecular Design Towards Efficient Oleds With Superior mentioning

confidence: 99%

Section: Design Of Tadf Molecules With Non-doped Capabilities In Tadfmentioning

confidence: 99%

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Liang

Zheng

2019

Chemistry A European J

194

123

View full text Add to dashboard Cite

show abstract

“…Recently, we achieved a series of donor-acceptor molecules with HLCT state after the careful manipulation of the distance, torsion angle and strength between the donor and acceptor moieties [7,8,33,34,47,54,55]. The quantified natural transition orbital (NTO) analysis indicated that the holes and particles of such molecules always exhibited obvious orbital separation and certain orbital overlap simultaneously.…”

Section: The Design Principle For the S 1 State Of Hot Exciton Materialsmentioning

confidence: 99%

Reverse intersystem crossing from upper triplet levels to excited singlet: a ‘hot excition’ path for organic light-emitting diodes

Yao

Yang

et al. 2015

Phil. Trans. R. Soc. A.

Self Cite

116

View full text Add to dashboard Cite

Since researches on the fate of highly excited triplet states demonstrated the existence of reverse intersystem crossing (RISC) from upper triplet levels to singlet manifold in naphthalene, quinoline, isoquinoline, etc. in the 1960s, this unique photophysical process was then found and identified in some other aromatic materials. However, the early investigations mainly focus on exploring the mechanism of this photophysical process; no incorporation of specific application was implemented. Until recently, our group innovatively used this ‘sleeping’ photophysical process to enhance the efficiency of fluorescent organic light-emitting diodes by simultaneously harvesting singlet and triplet excitons. Efforts are devoted to developing materials with high photoluminescence efficiency and effective RISC through appropriate molecular design in a series of donor–acceptor material systems. The experimental and theoretical results indicate that these materials exhibit hybridized local and charge-transfer excited state, which achieve a combination of the high radiation from local excited state and the high T m → S n ( m ≥2, n ≥1) conversion along charge-transfer excited state. As expected, the devices exhibited favourable external quantum efficiency and low roll-off, and especially an exciton utilization efficiency exceeding the limit of 25%. Considering the significant progress made in organic light-emitting diodes with this photophysical process, we review the relevant mechanism and material systems, as well as our design principle in materials and device application.

show abstract

“…Where, the excited state µ e was smaller and near to 10 D, and the LE state was dominant component to S 1 . If µ e was larger than the typical CT molecule DMABN of 23 D, the CT state was dominant component. Between the both, the mixed state was considered as a hybridized composition containing LE and CT component.…”

Section: Resultsmentioning

confidence: 99%

Exploration of High Efficiency AIE‐Active Deep/Near‐Infrared Red Emitters in OLEDs with High‐Radiance

Wan

Tong

Zhang

et al. 2019

Advanced Optical Materials

View full text Add to dashboard Cite

Limiting by classic donor–acceptor (D–A) strategy based on charge transfer (CT) process dominated emission, the high‐efficiency organic deep/near infrared red (DR/NIR) emitters with desirable photoluminescence quantum yields (PLQYs) and satisfactory excitons utilization efficiencies (EUEs) are still a challenge. Herein, three new DR/NIR luminogens (TNZPPI, TNZtPPI and TNZ2tPPI) based on naphtho[2,3‐c][1,2,5]thiadiazole (NZ) group are synthesized. Their interesting characterization of hybrid excited states containing tuned local excited (LE) and CT components are confirmed, and the effective high‐lying reverse intersystem crossing (RISC) channel might be activated because of their larger T2–T1 energy gap and smaller T4–S2 energy splitting. Thanks for their higher fluorescence quantum yields in film (24–38%), the TNZPs‐based non‐doped devices exhibit bright NIR emission with higher maximum radiance of 21447–36027 mW Sr−1 m−2, whose performance are better than most reported pure organic NIR devices. Enjoying deep analysis of their solvation effect and aggregation‐induced emission (AIE)‐activity, the doped organic light emitting diodes (OLEDs) are fabricated, whose performances are very good with identical National Television System Committee saturated red‐emitting behaviors. The results in TNZPs show that the electronic effect of molecule structure and intermolecular interactions all are relative to their performance, and which is very important for the design high‐efficiency NZ‐based OLED materials.

show abstract

Enhanced proportion of radiative excitons in non-doped electro-fluorescence generated from an imidazole derivative with an orthogonal donor–acceptor structure

Cited by 207 publications

References 17 publications

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Thermally Activated Delayed Fluorescence Materials: Towards Realization of High Efficiency through Strategic Small Molecular Design

Reverse intersystem crossing from upper triplet levels to excited singlet: a ‘hot excition’ path for organic light-emitting diodes

Exploration of High Efficiency AIE‐Active Deep/Near‐Infrared Red Emitters in OLEDs with High‐Radiance

Contact Info

Product

Resources

About