Red and Green Quantum Dot Color Filter for Full-Color Micro-LED Arrays

Wang, Qingqian; Li, Depeng; Bai, Xue; Li, Shang; Liu, Pai; Sun, Xiaowei

doi:10.3390/mi13040595

Cited by 15 publications

(12 citation statements)

References 20 publications

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“…However, both of them are not easy targets to be achieved. Mass transfer and epitaxial growth for fabricating RGB micro-LEDs become extremely difficult as the chip size shrinks and the pixel density grows [ 4 ]. To make the situation worse, the external quantum efficiency (EQE) of the micro-LEDs tends to deteriorate as we reduce the size of the device [ 5 , 6 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

et al. 2023

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Colloidal CdSe/ZnS quantum dots (QD) enhanced micro-LEDs with sizes varying from 10 to 100 μm were fabricated and measured. The direct photolithography of quantum-dot-contained photoresists can place this color conversion layer on the top of an InGaN-based micro-LED and have a high throughput and semiconductor-grade precision. Both the uncoated and coated devices were characterized, and we determined that much higher brightness of a QD-enhanced micro-LED under the same current level was observed when compared to its AlGaInP counterpart. The color stability across the device sizes and injection currents were also examined. QD LEDs show low redshift of emission wavelength, which was recorded within 1 nm in some devices, with increasing current density from 1 to 300 A/cm2. On the other hand, the light conversion efficiency (LCE) of QD-enhanced micro-LEDs was detected to decrease under the high current density or when the device is small. The angular intensities of QD-enhanced micro-LEDs were measured and compared with blue devices. With the help of the black matrix and omnidirectional light emission of colloidal QD, we observed that the angular intensities of the red and blue colors are close to Lambertian distribution, which can lead to a low color shift in all angles. From our study, the QD-enhanced micro-LEDs can effectively increase the brightness, the color stability, and the angular color match, and thus play a promising role in future micro-display technology.

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Section: Introductionmentioning

confidence: 99%

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

et al. 2023

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“…The integration of QDs and μLED arrays demonstrates a high potential for achieving high-resolution full-color displays. Coating QDs on substrates can be achieved through photolithography, transfer printing, and inkjet printing. − The smallest RGB subpixel pattern resolutions achieved with these QD fabrications are 14 μm × 14 μm, 5 μm × 39 μm, and 50 μm × 50 μm . For these applications, a high-efficiency blue light source with an InGaN/GaN structure is commonly used to excite the material and achieve a full-color display. , Researchers have explored various methods to passivate small-sized μLEDs, including changing the material of the passivation layer − or growing denser films using the ALD process. − Passivation of sidewalls using chemical solutions has also been proposed to reduce leakage current in small-sized μLEDs. − While these methods can improve device performance, they also increase process costs.…”

Section: Introductionmentioning

confidence: 99%

“…10−14 The smallest RGB subpixel pattern resolutions achieved with these QD fabrications are 14 μm × 14 μm, 12 5 μm × 39 μm, 13 and 50 μm × 50 μm. 14 For these applications, a high-efficiency blue light source with an InGaN/GaN structure is commonly used to excite the material and achieve a full-color display. 15,16 Researchers have explored various methods to passivate small-sized μLEDs, including changing the material of the passivation layer 17−20 or growing denser films using the ALD process.…”

Section: ■ Introductionmentioning

confidence: 99%

Current Confinement Effect on the Performance of Blue Light Micro-LEDs with 10 μm Dimension

Hsu,

Lin,

et al. 2023

ACS Omega

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The current confinement effect on the micro-LED (μLED) with a 10 μm dimension was simulated using SpeCLED software. In this study, three p-contact sizes were considered: 2 μm × 2 μm, 5 μm × 5 μm, and 8 μm × 8 μm dimensions for μLEDs with a 10 μm dimension. According to the simulation data, the highest external quantum efficiency (EQE) of 13.24% was obtained with a 5 μm × 5 μm contact size. The simulation data also showed that the μLEDs with narrow contact sizes experienced higher operating temperatures due to the current crowding effect. The experimental data revealed a red-shift effect in narrow contact sizes, indicating higher heat generation in those devices. As the contact sizes increased from 2 to 8 μm, the turn-on voltage decreased due to lower equivalent resistance. Additionally, the leakage current increased from 44 pA to 1.6 nA at a reverse voltage of −5 V. The study found that the best performance was achieved with a contact ratio of 0.5, which resulted in the highest EQE at 9.95%. This superior performance can be attributed to the better current confinement of the μLED compared to the μLED with a contact ratio of 0.8, resulting in lower leakage current and improved current spreading when compared to the μLED with a contact ratio of 0.2.

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“…In display fields, a new luminescence material is gradually replacing phosphors due to its narrow emission width, saturated color, and tunable emission [13,14]. This material is named QDs because of its quantum confinement effect and nanoscale dimension [15] There are roughly three kinds of QD materials for display application: II-VI semiconductor QDs, III-V semiconductor QDs, including perovskite QDs (PQDs), of which the corresponding representatives are shown in Figure 1a-c.…”

Section: Introductionmentioning

confidence: 99%

Perovskite Quantum Dots for Emerging Displays: Recent Progress and Perspectives

et al. 2022

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The excellent luminescence properties of perovskite quantum dots (PQDs), including wide excitation wavelength range, adjustable emission wavelength, narrow full width at half maximum (FWHM), and high photoluminescence quantum yield (PLQY), highly match the application requirements in emerging displays. Starting from the fundamental structure and the related optical properties, this paper first introduces the existing synthesis approaches of PQDs that have been and will potentially be used for display devices, and then summarizes the stability improving approaches with high retention of PQDs’ optical performance. Based on the above, the recent research progress of PQDs in displays is further elaborated. For photoluminescent display applications, the PQDs can be embedded in the backlighting device or color filter for liquid crystal displays (LCD), or they may function as the color conversion layer for blue organic light-emitting diodes (OLED) and blue micro-scale light-emitting diodes (μLED). In terms of next-generation electroluminescent displays, notable progress in perovskite quantum-dot light emitting diodes (PeQLED) has been achieved within the past decade, especially the maximum external quantum efficiency (EQE). To conclude, the key directions for future PQD development are summarized for promising prospects and widespread applications in display fields.

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Red and Green Quantum Dot Color Filter for Full-Color Micro-LED Arrays

Cited by 15 publications

References 20 publications

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs

Current Confinement Effect on the Performance of Blue Light Micro-LEDs with 10 μm Dimension

Perovskite Quantum Dots for Emerging Displays: Recent Progress and Perspectives

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