Solid-state white light-emitting electrochemical cells based on scattering red color conversion layers

Lin, Guan Rung; Cheng, Jing Rong; Wang, Chi Wei; Sarma, Monima; Chen, Hsiao-Fan; Su, Hai‐Ching; Chang, Chih‐Hao; Wong, Ken‐Tsung

doi:10.1039/c5tc02835c

Cited by 26 publications

(19 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most important of all, the phosphorescent nature of iTMCs commonly results in more efficient electroluminescence (EL) than other fluorescent materials. Some LECs employing efficient iTMCs were reported to achieve similar device performance to that published for OLEDs. − In addition to efficient emissive materials, optimizing the carrier balance, that is, balancing the number of electrons and holes, of LECs is critical to take full advantage of efficient emissive materials. Several device engineering methods to improve the balance of carrier transport, for example, carrier trapping or blocking, − adjusting carrier injection, − salt incorporation, − modifying carrier transporting, − emissive-layer thickness optimization, − and optimizing emission zone position ,,− were shown for improving the device performance of LECs .…”

Section: Introductionmentioning

confidence: 89%

“…On the other hand, extraction of the light trapped in the optical structure of LECs is another feasible way to enhance device efficiency with optical approaches. For instance, significantly improved device performance was shown by light extraction from substrate ,− and waveguide modes. ,, Recently, promising external quantum efficiency (EQE) and power efficiency of 35% and 83 lm W –1 from blue LECs based on substrates with embedded diffusive layers have been reported . Optical optimization for light extraction is independent of the employed emissive materials and thus is effective for all LECs, especially useful for white LECs. − However, most reported works focused on a single optimization approach, that is, employing efficient emissive material, optimizing carrier balance or maximizing light extraction, but few works on a combinational way for overall optimization have been reported.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells

Luo

et al. 2020

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Light-emitting electrochemical cells (LECs) show high technical potential for display and lighting utilizations owing to the superior properties of solution processability, low operation voltage, and employing inert cathodes. For maximizing the device efficiency, three approaches including development of efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction have been reported. However, most reported works focused on only one of the three optimization approaches. In this work, a combinational approach is demonstrated to optimize the device efficiency of LECs. A sophisticatedly designed yellow complex exhibiting a superior steric hindrance and a good carrier balance is proposed as the emissive material of light-emitting electrochemical cells and thus the external quantum efficiency (EQE) is up to 13.6%. With an improved carrier balance and reduced self-quenching by employing the host–guest strategy, the device EQE can be enhanced to 16.9%. Finally, a diffusive layer embedded between the glass substrate and the indium-tin-oxide layer is utilized to scatter the light trapped in the layered device structure, and consequently, a high EQE of 23.7% can be obtained. Such an EQE is impressive and consequently proves that the proposed combinational approach including adopting efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction is effective in realizing highly efficient LECs.

show abstract

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells

Luo

et al. 2020

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…To further enhance the efficiency of LEC devices, TiO 2 nanoparticles (NPs) of two sizes were doped into red CCLs to induce scattering and thus to increase the EL outcoupling efficiency . Large NPs (250 nm) scattered and redirected the light passing through a red CCL and further enhanced the extracted light.…”

Section: Light Extractionmentioning

confidence: 99%

Optical Techniques for Light‐Emitting Electrochemical Cells

2018

ChemPlusChem

Self Cite

View full text Add to dashboard Cite

The concept of solid‐state light‐emitting electrochemical cells (LECs), proposed in 1995, opened a new field in display and lighting technologies. The key advantage of this technology derives from a single emissive layer containing an emissive material and an ionic salt. Mobile ions in the emissive layer induce electrochemical doping at electrodes and thus the operation voltage can be reduced even if using air‐stable electrodes. Since the first demonstration of LECs, many materials‐oriented efforts have been made in improving device performance of LECs. However, some difficulties arising from material properties limit further optimizing the device characteristics of LECs. Recently, optical techniques have been shown to achieve better device properties without using new materials. Light extraction techniques recycle the light trapped in layered device structure and thus enhance the light output and efficiency of LECs. Recombination zone probing techniques offer direct evidence of carrier balance in LECs and is helpful in optimizing device performance. Spectral filtering based on microcavity effects and localized surface plasmon resonance from metal nanoparticles have the advantages of easy fabrication and compatibility with device processing of LECs. This Minireview provides an overview of the three categories of recent advances in optical techniques for LECs.

show abstract

“…Several LECs based on efficient iTMCs have been reported to achieve comparable device efficiencies to those measured for OLEDs [19–25] . However, most high‐efficiency iTMCs are blue, [22–24] green, [19, 20] and yellow, [25] whereas the reported red iTMCs commonly show lower photoluminescence quantum yields, [26–29] which limit further enhancement of the device efficiency of host–guest white LECs based on iTMCs. Recently, incorporation of efficient QDs in LECs [30–32] has inspired the idea of the hybrid white LECs combining a yellow iTMC and blue QDs [33] .…”

Section: Introductionmentioning

confidence: 99%

“…In addition, iTMCs commonly show higher electroluminescence (EL) efficiencies due to their phosphorescent nature. Several LECs based on efficient iTMCs have been reported to achieve comparable device efficiencies to those measured for OLEDs [19–25] . However, most high‐efficiency iTMCs are blue, [22–24] green, [19, 20] and yellow, [25] whereas the reported red iTMCs commonly show lower photoluminescence quantum yields, [26–29] which limit further enhancement of the device efficiency of host–guest white LECs based on iTMCs.…”

Section: Introductionmentioning

confidence: 99%

Hybrid White‐Light‐Emitting Electrochemical Cells Based on a Blue Cationic Iridium(III) Complex and Red Quantum Dots

Tang

Chiu

Luo

et al. 2020

Chemistry A European J

View full text Add to dashboard Cite

Solid‐state white light‐emitting electrochemical cells (LECs) show promising advantages of simple solution fabrication processes, low operation voltage, and compatibility with air‐stable cathode metals, which are required for lighting applications. To date, white LECs based on ionic transition metal complexes (iTMCs) have shown higher device efficiencies than white LECs employing other types of materials. However, lower emission efficiencies of red iTMCs limit further improvement in device performance. As an alternative, efficient red CdZnSeS/ZnS core/shell quantum dots were integrated with a blue iTMC to form a hybrid white LEC in this work. By achieving good carrier balance in an appropriate device architecture, a peak external quantum efficiency and power efficiency of 11.2 % and 15.1 lm W−1, respectively, were reached. Such device efficiency is indeed higher than those of the reported white LECs based on host–guest iTMCs. Time‐ and voltage‐dependent electroluminescence (EL) characteristics of the hybrid white LECs were studied by means of the temporal evolution of the emission‐zone position extracted by fitting the simulated and measured EL spectra. The working principle of the hybrid white LECs was clarified, and the high device efficiency makes potential new white‐emitting devices suitable for solid‐state lighting technology possible.

show abstract

Solid-state white light-emitting electrochemical cells based on scattering red color conversion layers

Abstract: Efficient white LECs based on recycling the trapped EL in waveguide and substrate mode.

Cited by 26 publications

References 33 publications

Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells

Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells

Optical Techniques for Light‐Emitting Electrochemical Cells

Hybrid White‐Light‐Emitting Electrochemical Cells Based on a Blue Cationic Iridium(III) Complex and Red Quantum Dots

Contact Info

Product

Resources

About