Multiple strategies towards high-efficiency white organic light-emitting diodes by the vacuum deposition method

Liu, Hui; Liu, Futong; Lü, Ping

doi:10.1039/d0tc00085j

Cited by 32 publications

(25 citation statements)

References 216 publications

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“…Experiments and Monte Carlo-based simulations on transport in organic semiconductors reveal deviations from the conventional current density equations ( 29) and (30). Particularly the ratio between diffusion coefficient D and mobility μ would deviate from the standard Einstein relation, [151][152][153]…”

Section: Generalized Einstein Relationmentioning

confidence: 99%

“…© 2021 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH relation (40) offers the advantage that the mobilities μ n/p can be expressed via the diffusion coefficients D n/p and vice versa, that is, one of the two material constants can be eliminated from the current density Equations ( 29) and (30). This factor G contains the information on the distribution function f and the density of states [160,161] ( )…”

Section: (21 Of 37)mentioning

confidence: 99%

“…[159,180,181] The Scharfetter-Gummel algorithm (or Gummel algorithm for steady-state simulations [182] ) replaces the native interpolation of the densities n and p between adjacent mesh points in the FD and FEM methods by an exponential interpolation. [183] Exponential changes between adjacent grid point are consequence of the particular form of the current density equations (29,30) and are difficult to address in finite difference and finite element methods, because they interpolate either linearly (FD, FEM) or with polynomials of the order less than four (FEM). This rather technical twist enhances the stability of the solver.…”

Section: Remarks On Solving Strategies*mentioning

confidence: 99%

“…[144,146,164] However, most contact situations are not ideal (i.e., nonohmic), in particular when the organic layers are not intentionally doped. In such cases, the actually exchanged current density C j needs to be incorporated as boundary condition to the current density equations ( 29) and (30).…”

Section: Consideration Of Contact Interfacesmentioning

confidence: 99%

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Simulation of Charge Carriers in Organic Electronic Devices: Methods with their Fundamentals and Applications

Zojer

2021

Advanced Optical Materials

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Device modeling is an established tool to design and optimize organic electronic devices, be them organic light emitting diodes, organic photovoltaic devices, or organic transistors and thin‐film transistors. Further, reliable device simulations form the basis for elaborate experimental characterizations of crucial mechanisms encountered in such devices. The present contribution collects and compares contemporary model approaches to describe charge transport in devices. These approaches comprise kinetic Monte Carlo, the master equation, drift‐diffusion, and equivalent circuit analysis. This overview particularly aims at highlighting the following three aspects for each method: i) The foundation of a method including inherent assumptions and capabilities, ii) how the nature of organic semiconductors enters the model, and iii) how major tuning handles required to control the device operation are accounted for, namely temperature, external field, and provision of mobile carriers. As these approaches form a hierarchy of models suitable for multiscale modeling, this contribution also points out less established or even missing links between the approaches.

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Section: Generalized Einstein Relationmentioning

confidence: 99%

Section: (21 Of 37)mentioning

confidence: 99%

Section: Remarks On Solving Strategies*mentioning

confidence: 99%

Section: Consideration Of Contact Interfacesmentioning

confidence: 99%

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Simulation of Charge Carriers in Organic Electronic Devices: Methods with their Fundamentals and Applications

Zojer

2021

Advanced Optical Materials

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“…Compared with polymeric light-emitting materials, small molecule luminescent materials are easier to synthesize and purify, and their structure can be ne-tuned through appropriate molecular design. OLEDs based on small molecules can be fabricated either by vacuum deposition method or by solution spin-coating method [24][25][26] . Among the small-molecule luminescent materials, luminescent materials with high photoluminescence quantum (Φ PL ) and excellent charge transport characteristics can effectively improve the electroluminescence (EL) e ciency [17,27] .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Luminescent Properties of 1,4,5-Triphenylimidazole‒Phenothiazine Fluorophores

Qian

Yang

Zhang

et al. 2022

Preprint

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Two blue donor-acceptor fluorophores with 1,4,5-triphenylimidazole as the electron-transporting unit and phenothiazine as the hole-transporting unit were synthesized by grafting 1,4,5-triphenylimidazole moieties onto 3- and 3,7-position of the phenothiazine core and characterized by spectroscopic methods. Their thermal stability, photophysical, electrochemical and electroluminescence properties were systematically investigated. These compounds exhibit good thermal stability and show blue emission in dichloromethane solution and thin solid films. The solution-processed doped devices were fabricated by using these fluorophores as the emitting dopant in 1,3-bis(N-carbazolyl)benzene host, in which the device fabricated from the fluorophore containing two 1,4,5-triphenylimidazole moieties exhibited blue emission with a luminance of 648 cd/m2 and external quantum efficiency of 1.48%.

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Achieving High Electroluminescence Efficiency and High Color Rendering Index for All‐Fluorescent White OLEDs Based on an Out‐of‐Phase Sensitizing System

Líu

Chen

et al. 2021

Adv Funct Materials

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Sensitizing conventional fluorescence (CF) dopants with thermally activated delayed fluorescence (TADF) materials has achieved considerable progress, by which the advantages of TADF materials and CF dopants can be fully harnessed. However, the usually used co‐phase configuration of CF dopant‐engaged sensitizing systems often encounters exciton loss due to Dexter energy transfer (DET). Herein, an effective out‐of‐phase configuration is proposed to sensitize CF dopants in the fabrication of white organic light‐emitting diodes (WOLEDs). Based on a new efficient sky‐blue TADF luminogen DCP‐BP‐DPAC which has an electroluminescence (EL) peak at 486 nm and an EL efficiency of 26.6%, a green TADF material BDMAC‐XT, and a red CF dopant DBP sensitized by BDMAC‐XT through an out‐of‐phase configuration without interlayer, efficient WOLEDs are successfully fabricated. By further adopting orange TBRB or 4CzTPNBu as intermediate sensitizers, more efficient energy transfer to DBP is achieved via Förster energy transfer. Through step‐by‐step energy transfer and elimination of excess DET process, high‐performance all‐fluorescent WOLEDs are achieved, providing excellent EL efficiencies over 23.0%, and highly stable white light with a high color rendering index of 87. The outstanding EL performance and high‐quality emission color demonstrate the great potential of the proposed out‐of‐phase design for sensitizing systems of WOLEDs.

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Multiple strategies towards high-efficiency white organic light-emitting diodes by the vacuum deposition method

Abstract: This review summarizes the progress in WOLEDs in recent years including all phosphorescent WOLEDs, hybrid WOLEDs, all fluorescence WOLEDs, doping-free WOLEDs, and single-emitter WOLEDs.

Cited by 32 publications

References 216 publications

Simulation of Charge Carriers in Organic Electronic Devices: Methods with their Fundamentals and Applications

Simulation of Charge Carriers in Organic Electronic Devices: Methods with their Fundamentals and Applications

Synthesis and Luminescent Properties of 1,4,5-Triphenylimidazole‒Phenothiazine Fluorophores

Achieving High Electroluminescence Efficiency and High Color Rendering Index for All‐Fluorescent White OLEDs Based on an Out‐of‐Phase Sensitizing System

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