High efficiency blue/green/yellow/red fluorescent organic light-emitting diodes sensitized by phosphors: general design rules and electroluminescence performance analysis

Yao, Jingwen; Ying, Shian; Sun, Qian; Dai, Yanfeng; Qiao, Xianfeng; Yang, Dezhi; Chen, Jiangshan; Ma, Dongge

doi:10.1039/c9tc03666k

Cited by 24 publications

(17 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Notably, there is a wide overlap between the absorption spectra of emitter molecules and the emission spectra of assistant dopants, which indicated efficient FRET process from the lowest excited singlet state of the TADF assistant dopant to that of the emitter guest. 36 As described in earlier works, the FRET process will play an important role in the sensitizing process of fluorescent emitters; therefore, the photophysical characteristics of the codoped mCBP film with both the TADF sensitizer and the fluorescent emitter are investigated, as shown in Figure 2a. We note that a Dexter energy transfer will facilitate the energytransfer process of the triplet excitons of TXO-TPA to the DBP, leading to the low efficiency of the exciton utilization.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The TADF sensitizer shows a broad emission spectrum centered at 565 nm with a full-width at half-maximum (FWHM) of 102 nm due to its charge-transfer characteristic, which is beneficial for overlaping with the absorption spectra of guest molecules. Notably, there is a wide overlap between the absorption spectra of emitter molecules and the emission spectra of assistant dopants, which indicated efficient FRET process from the lowest excited singlet state of the TADF assistant dopant to that of the emitter guest …”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

High-Efficiency Red-Fluorescent Organic Light-Emitting Diodes with Excellent Color Purity

Liu

et al. 2021

J. Phys. Chem. C

View full text Add to dashboard Cite

Thermally activated delayed fluorescence (TADF)-sensitized fluorescent OLEDs are promising for next-generation OLEDs. However, the performance of these OLEDs with deviated CIE coordinates from the fluorescent emitters is still unsatisfactory due to the insufficient Förster resonance energy transfer (FRET). Here we report a rational strategy to construct a highly efficient TADF-sensitized fluorescent OLED system by the dedicated selection of the host and the TADF sensitizer. Benefiting from the efficient energy-transfer process from TXO-TPA to DBP, the TADF-sensitized fluorescent OLEDs exhibited a maximum EQE of 16.9%. Furthermore, a new factor, the sensitization efficiency (SE), was first introduced to quantitatively evaluate the contribution of the fluorescent emission. A high SE up to 96.4% can be achieved for the reported OLEDs with CIE coordinates of (0.65, 0.35), which are very close to the standard red CIE coordinates of (0.67, 0.33). Our discussion will aid in the design and evaluation of more efficient TADF-sensitized fluorescent OLEDs.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

High-Efficiency Red-Fluorescent Organic Light-Emitting Diodes with Excellent Color Purity

Liu

et al. 2021

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…In particular, Dexter energy transfer between the triplet states of the TADF and fluorescent molecules must be largely precluded in order to avoid the generation of nonradiative triplet excitons (T 1 FE ) on the fluorescent emitters. − The important question that then arises is whether Dexter energy transfer could be minimized by a rational choice of the fluorescent emitter. Here, in order to address this question, we have investigated the electronic structure of a series of fluorescent emitters (see Figure ) that were recently used in hyperfluorescence-based OLED devices: 2,5,8,11-tetra- tert -butylperylene (TBPe), ,,,, 9,10-bis[ N , N -di( p -tolyl)-amino]anthracene (TTPA), ,− 2,8-di- tert -butyl-5,11-bis(4- tert -butylphenyl)-6,12-diphenyltetracene (TBRb), ,,,,− 5,6,11,12-tetraphenyltetracene (rubrene), − and tetraphenyldibenzoperiflanthene (DBP), ,, and terrylene …”

mentioning

confidence: 99%

Hyperfluorescence-Based Emission in Purely Organic Materials: Suppression of Energy-Loss Mechanisms via Alignment of Triplet Excited States

Abroshan

Coropceanu

Brédas

2020

ACS Materials Lett.

View full text Add to dashboard Cite

Hyperfluorescence has received significant attention as a promising strategy to design organic light-emitting diodes (OLEDs) with high color purity and enhanced stability. In this approach, emitters displaying strong and narrowband fluorescence are integrated in thin films that contain sensitizers showing efficient thermally activated delayed fluorescence (TADF). To ensure high performance, the energies of the electronic states in the fluorescent emitters must be well-aligned, with respect to those in the TADF molecules, in order to enable a fast rate of Forster singlet-exciton energy transfer from the latter to the former. Here, we performed molecular dynamics simulations and density functional theory calculations to study a series of fluorescent emitters commonly considered in hyperfluorescence OLEDs. For all these emitters, the lowest triplet excited state (T 1 FE ) is found to locate substantially below the lowest singlet excited state (S 1 FE

show abstract

“…However, the Dexter energy transfer from triplet of β-DPTZN to triplet of rubrene should be increased as well, which can lead to the decline of EL efficiency at high doping concentration of β-DPTZN. Although some heavy metal complex based phosphor sensitized fluorescence OLEDs have been reported [16][17][18][19][20][21][22][23] , here we demonstrated purely organic phosphor sensitized fluorescence OLEDs with higher efficiency for the first time. Table 1.…”

mentioning

confidence: 60%

Purely Organic Phosphor Sensitization Based Highly Efficient Electrofluorescence Material

Wang¹,

Bian²,

Wei³

et al. 2021

Preprint

View full text Add to dashboard Cite

Pure organic room temperature phosphorescence (RTP) materials are considered as potential candidates for replacing precious metal-based complexes to fabricate highly efficient organic light emitting devices (OLEDs). However, for reported RTP materials, low photoluminescence quantum yields (PLQYs) in thin film state seriously impede their applications in OLEDs. On the other hand, how using normal organic fluorescence materials to fabricate OLEDs with an internal quantum efficiency (IQE) over 25% remains a great unaddressed issue beyond the thermally activated delayed fluorescence (TADF) sensitization approach. Here, we establish a strategy to construct highly efficient OLEDs based on pure organic RTP material sensitized fluorescence emitter. The key point for our strategy is that benzimidazole-triazine molecules (PIM-TRZ), 2,6-di(phenothiazinyl)naphthalene (β-DPTZN) and 5,6,11,12-tetraphenylnaphthacene (rubrene) were screened as host, phosphor sensitizer and fluorescent emitter, respectively. Detail photophysical characterizations demonstrate that the host material PIMTRZ with unique RTP nature is critical for achieving phosphor sensitizing process. As an organic RTP compound, the singlet and triplet state energy levels of β-DPTZN perfectly match with those of PIMTRZ, resulting in the formation and lasting existence of phosphor’s excitons in emitting layer. The large overlap between the absorption spectrum of rubrene and PL spectrum of PIM-TRZ:10% β-DPTZN film can facilitate the Förster energy transfer from the triplet β-DPTZN to the singlet rubrene and the finally displayed fluorescence is derived from singlet excited states of rubrene. The perfect collocation of host, phosphorescent sensitizer and fluorescent emitter in the emitting layer promise the predominant performance of the devices with external quantum efficiency (EQE) of 15.7%. The PLQY of emitting layer is 60.3%, and therefore about 90% carrier injection induced excitons are harvested for light emission. We present a new strategy to fabricate efficient fluorescent devices by employing ingenious combination of host, phosphorescent sensitizer and fluorescent emitter, which is significant to the development of OLEDs.<br>

show abstract

High efficiency blue/green/yellow/red fluorescent organic light-emitting diodes sensitized by phosphors: general design rules and electroluminescence performance analysis

Abstract: Phosphor sensitized fluorescent organic light-emitting diodes realize high efficiency and low roll-off at high luminance.

Cited by 24 publications

References 37 publications

High-Efficiency Red-Fluorescent Organic Light-Emitting Diodes with Excellent Color Purity

High-Efficiency Red-Fluorescent Organic Light-Emitting Diodes with Excellent Color Purity

Hyperfluorescence-Based Emission in Purely Organic Materials: Suppression of Energy-Loss Mechanisms via Alignment of Triplet Excited States

Purely Organic Phosphor Sensitization Based Highly Efficient Electrofluorescence Material

Contact Info

Product

Resources

About