Eliminate angular color shift in top‐emitting OLEDs through cavity design

Dong, Chen; Fu, Xiangyu; Amoah, Stephen; Rozelle, Adam; Shin, Dong-Sig; Salehi, Amin; Mendes, Juliana; So, Franky

doi:10.1002/jsid.792

Cited by 15 publications

(22 citation statements)

References 16 publications

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“…The tradeoffs are a compromised efficiency and a large angular colour shift. Therefore, proper OLED structure parameter optimizations 97 and better cavity designs for mitigating colour shift 98 are still needed.…”

Section: Colour Performancementioning

confidence: 99%

Mini-LED, Micro-LED and OLED displays: present status and future perspectives

et al. 2020

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Presently, liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays are two dominant flat panel display technologies. Recently, inorganic mini-LEDs (mLEDs) and micro-LEDs (μLEDs) have emerged by significantly enhancing the dynamic range of LCDs or as sunlight readable emissive displays. "mLED, OLED, or μLED: who wins?" is a heated debatable question. In this review, we conduct a comprehensive analysis on the material properties, device structures, and performance of mLED/μLED/OLED emissive displays and mLED backlit LCDs. We evaluate the power consumption and ambient contrast ratio of each display in depth and systematically compare the motion picture response time, dynamic range, and adaptability to flexible/transparent displays. The pros and cons of mLED, OLED, and μLED displays are analysed, and their future perspectives are discussed.

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Section: Colour Performancementioning

confidence: 99%

Mini-LED, Micro-LED and OLED displays: present status and future perspectives

et al. 2020

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“…[1][2][3][4][5] Benefiting from the high aperture ratio, the inverted top-emitting OLEDs (TEOLEDs) have been widely adopted to achieve high-efficiency active-matrix display. [6][7][8][9][10] The full width at half…”

Section: Introductionmentioning

confidence: 99%

“…[ 1–5 ] Benefiting from the high aperture ratio, the inverted top‐emitting OLEDs (TEOLEDs) have been widely adopted to achieve high‐efficiency active‐matrix display. [ 6–10 ] The full width at half maximum (FWHM) and current efficiency (CE) of the TEOLEDs are significantly optimized owing to the micro‐cavity effect of the top‐emitting structure, promoting the applications in ultra‐high‐definition displays and micro‐displays. [ 11,12 ] However, one major challenge of the TEOLEDs is the severe waveguide and plasmonic losses, which hinders the light output‐coupling and results in the low external quantum efficiency (EQE).…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Light Output‐Coupling of Inverted Top‐Emitting Organic Light‐Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles

Zhao

Niu

Shi

et al. 2022

Adv Materials Inter

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maximum (FWHM) and current efficiency (CE) of the TEOLEDs are significantly optimized owing to the micro-cavity effect of the top-emitting structure, promoting the applications in ultra-high-definition displays and micro-displays. [11,12] However, one major challenge of the TEOLEDs is the severe waveguide and plasmonic losses, which hinders the light outputcoupling and results in the low external quantum efficiency (EQE). [13,14] Introducing the localized surface plasmon resonance (LSPR) in the device is an effective way to increase the EQE of the OLEDs. [15,16] The LSPR is generated by overlapping the local electromagnetic field of excitons in the emitting layer and the surface plasmons of the noble metal in form of the nanowire and nanoparticles (NPs). [17][18][19][20][21] When the absorption peak of the metal NPs matches the emission wavelength of the device, the local electromagnetic fields around the NPs at a specific wavelength are enhanced. [22,23] More importantly, the LSPR is greatly influenced by the size of the noble metal NPs. [24,25] By precisely adjusting the size and the spacing of the NPs, the resonance wavelength of the NPs can be tuned to well match the wavelength of the electroluminescence (EL) spectra of OLEDs. [26,27] However, there are few reports on the effect of the LSPR on the inverted TEOLEDs.In this study, we have introduced a light output-coupling layer (LOCL) composed of AgNPs and MoO x on the top capping layer (CPL) of the inverted TEOLED device. The AgNPs in the LOCL could significantly improve the light output-coupling of the TEOLED owing to the LSPR, and the MoO x in the LOCL could effectively protect the water-and oxygen-sensitive electron injection material. In addition, the FWHM is narrowed to 50 nm due to the micro-cavity effect of the top-emitting structure and the turn-on voltage (V on , calculated at the lowest brightness of ≈1 cd m −2 ) is decreased to 2.6 V with Ag 2 O doped 4,7-diphenyl-1,10-phenanthroline (Bphen) as electron injection layer (EIL). Through systematical analysis and the finite difference time domain simulation (FDTD), we found that when the thickness of the AgNPs was 0.5 nm and the thickness of MoO x was 20 nm, the light output-coupling of the device reached the best. The CE and the EQE were increased 1.53 and 1.3 times to 28.3 cd A −1 and 13.11%, and the luminance achieves 34 247 cd m −2 .In this study, a light out-coupling layer (LOCL) composed of Ag nanoparticles (NPs) and MoO x is introduced on top of the inverted top-emitting organic light-emitting diode (OLED). The full width at half maximum (FWHM) is narrowed to 50 nm due to the micro-cavity effect of the top-emitting structure and the turn-on voltage is as low as 2.6 V. The AgNPs in the LOCL significantly improves the light output-coupling of the OLED owing to the localized surface plasmon resonance, and the MoO x in the LOCL effectively protects the water-and oxygen-sensitive electron injection material. As a result, the performance of the OLED with the LOCL is significantly enhanced. The maximum...

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“…However, such polymer nanostructures cannot be easily integrated with TEOLEDs because of the complexity of their deposition process, which involves spin-coating or lithography [ 17 ]. Further, light scattering due to polymer thin films may additionally lead to pixel crosstalk [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Cavity-Suppressing Electrode Integrated with Multi-Quantum Well Emitter: A Universal Approach Toward High-Performance Blue TADF Top Emission OLED

et al. 2022

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A novel device structure for thermally activated delayed fluorescence (TADF) top emission organic light-emitting diodes (TEOLEDs) that improves the viewing angle characteristics and reduces the efficiency roll-off is presented. Furthermore, we describe the design and fabrication of a cavity-suppressing electrode (CSE), Ag (12 nm)/WO3 (65 nm)/Ag (12 nm) that can be used as a transparent cathode. While the TADF-TEOLED fabricated using the CSE exhibits higher external quantum efficiency (EQE) and improved angular dependency than the device fabricated using the microcavity-based Ag electrode, it suffers from low color purity and severe efficiency roll-off. These drawbacks can be reduced by using an optimized multi-quantum well emissive layer (MQW EML). The CSE-based TADF-TEOLED with an MQW EML fabricated herein exhibits a high EQE (18.05%), high color purity (full width at half maximum ~ 59 nm), reduced efficiency roll-off (~ 46% at 1000 cd m−2), and low angular dependence. These improvements can be attributed to the synergistic effect of the CSE and MQW EML. An optimized transparent CSE improves charge injection and light outcoupling with low angular dependence, and the MQW EML effectively confines charges and excitons, thereby improving the color purity and EQE significantly. The proposed approach facilitates the optimization of multiple output characteristics of TEOLEDs for future display applications.

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Eliminate angular color shift in top‐emitting OLEDs through cavity design

Abstract: OLEDs suffer from viewing angle dependent spectral shift due to microcavity effects. To address this issue, we introduce a novel top‐emitting OLED with a dielectric spacer that forms multiple cavity modes. The resulting device shows almost no color shift at different viewing angles.

Cited by 15 publications

References 16 publications

Mini-LED, Micro-LED and OLED displays: present status and future perspectives

Mini-LED, Micro-LED and OLED displays: present status and future perspectives

Enhancing the Light Output‐Coupling of Inverted Top‐Emitting Organic Light‐Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles

Cavity-Suppressing Electrode Integrated with Multi-Quantum Well Emitter: A Universal Approach Toward High-Performance Blue TADF Top Emission OLED

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