High efficiency color-temperature tunable organic light-emitting diode

Shih, Sheng-Hsu; Jou, Jwo‐Huei; Chavhan, Sudam; Su, Tsung-Hao; Yuan, Chih-Hsien; Wen, Jiawei; Chen, Pin-Ren; Tung, Fu-Ching; Tasi, Y. S.

doi:10.1039/c9tc05603c

Cited by 18 publications

(9 citation statements)

References 44 publications

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“…In practice, light emissions from OLEDs can be tuned either by blending compatible CPs or controlling the energy transfer between the CPs or a combination of both [ 3 , 4 , 5 ]. For example, a full-color emitter for white OLEDs (WOLEDs) can be achieved by blending different CPs that emit lights covering the entire visible spectrum.…”

Section: Introductionmentioning

confidence: 99%

Improving Photophysical Properties of White Emitting Ternary Conjugated Polymer Blend Thin Film via Additions of TiO2 Nanoparticles

et al. 2020

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The effect of TiO2 nanoparticles on the photophysical properties of ternary conjugated polymer (CP) blends of poly(9,9-dioctylfluorene-2,7-diyl) (PFO), poly 9,9-dioctylfluorene-alt-benzothiadiazole (F8BT) and poly(2-methoxy-5(2-ethylhexyl)-1,4 -phenylenevinylene (MEH-PPV) thin films was investigated. This ternary blend used a fixed amount of PFO as the donor with MEH-PPV and F8BT in various ratios as the acceptors. The solution-blending method and the spin-coating technique were used to prepare the blends and the thin films, respectively. Through efficient Förster Resonance Energy Transfer (FRET), the desired white emission was achieved with PFO/0.3 wt.% F8BT/0.5 wt.% MEH-PPV ternary blend thin film. Additions of nanoparticles up to 10 wt.% dramatically intensified the white emission which then dimmed at higher contents due to agglomerations. The current density–voltage characteristics of the nanocomposite thin films exhibited dependency on the content and distributions of the nanoparticles. Finally, a possible underlying mechanism for the intensification of emission is proposed.

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Section: Introductionmentioning

confidence: 99%

Improving Photophysical Properties of White Emitting Ternary Conjugated Polymer Blend Thin Film via Additions of TiO2 Nanoparticles

et al. 2020

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“…Candles can yield pleasant light with a little blue emission, , which might help prevent numerous blue hazards. − Candlelight is perfectly continuous in spectrum, free of ultraviolet radiation, and high in color rendition, , making candles an ideal illumination measure. However, they are not quite suitable for general lighting due to the fact that they are not energy-efficient and, worst of all, release greenhouse gases and PM 2.5 particles. − A proper substitute is hence highly desirable to mimic the pleasant color of candles while eliminating all the fatal drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Flexible Candlelight Organic LED on Mica

Chen

Weng

et al. 2022

ACS Appl. Electron. Mater.

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Candlelight-style, blue hazard-free light sources have been long desired in order to minimize the threats of blue emission on human health, artifacts, ecosystems, and night skies. Flexible light sources can enable numerous innovative products that are wearable, rollable, foldable, and portable. If also transparent, more applications including smart displays, lighting, signage, etc., can be implemented. However, current flexible lighting sources have issues like the use of environmentally unfriendly materials and poor lifetimes. Here, we show the fabrication and lifetime study of a candlelight-style organic light-emitting diode (LED) on high-flexibility, transparent mica that is 100% plastic-free. We found that the mica substrate coated with a transparent conductor survived a record-high bending curvature, i.e., 1/5 mm–1 and 50,000 bending cycles at a 7.5 mm bending radius. The candlelight organic LED fabricated thereon showed a good lifetime that is 83% of that on glass. The blue light-less emission permits at 100 lx an exposure limit of 47,000 s, while the exposure limit is 320 s for a cold-white counterpart; upon exposure at night for 1.5 h, it suppresses 1.6% melatonin, while 30% melatonin is suppressed for the cold-white counterpart. Our results demonstrate how blue hazard-free lighting sources are fabricated on eco-friendly mica that is highly flexible, and the resultant device showed a lifetime approaching that on glass due to its high resistance against moisture and oxygen penetration. The findings suggest that mica can be a good candidate for flexible transparent devices. We expect that these could bring up opportunities to promote omnifriendly lighting applications with a higher degree of design flexibility.

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“…Photo-biological effects have been reported to be affected by correlated color temperature (CCT) in a number of studies [27][28][29][30], whereas the fact that a CCT corresponds to multiple SPDs tend to be ignored in previous researches [31][32], resulting to the lack of requirements regarding spectrum in available standards for lamps and displays. In the fabrication of light source, the mixture of red, green and blue phosphors contributes to the final color [33][34][35], therefore a certain color corresponds to various possible phosphor proportions and photoluminescence spectrums [31].…”

Section: Introductionmentioning

confidence: 99%

Effects of Red Light on Circadian Rhythm: A Comparison Among Lamps With Similar Correlated Color Temperatures Yet Distinct Spectrums

Cai

Hao²,

Zeng

et al. 2021

IEEE Access

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Blue crest between the wavelength of 460 nm and 480 nm was reported to present melatonin suppression effects, whereas effects of red light on circadian rhythm regulation remain unclear. Spectrum plays an important role in circadian rhythm regulation, yet a lot of researches focused on the correlated color temperature, although a correlated color temperature value corresponds to various possible spectrums. Here, we performed human factor experiments with 3 lamps on 17 participants, comprising 9 males and 8 females. Our results showed that spectrums with high blue intensity tended to cause abnormal regulations of melatonin and cortisol, while the abnormalities were likely to be compensated by the 606-635-nm red light, which was indispensable for the photo-biological effects concerning circadian rhythm regulation. Abnormal circadian rhythm regulation was also found to be influenced by the illuminance, as abnormalities were significant in 500 lux whereas they were likely to disappear in 250 lux, implying the existence of threshold doses to trigger abnormities concerning circadian rhythm regulation. Furthermore, circadian rhythm responses were distinct between males and females. Our work may have implications for the development of light source, as we suggest that lighting source designers should increase the 606-635-nm intensity for bed room luminaires to decrease melatonin suppression effects.

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High efficiency color-temperature tunable organic light-emitting diode

Abstract: Rhythmic lighting with varying color-temperature and brightness like that of diurnal sunlight has now been recognized to be extremely crucial to human health.

Cited by 18 publications

References 44 publications

Improving Photophysical Properties of White Emitting Ternary Conjugated Polymer Blend Thin Film via Additions of TiO2 Nanoparticles

Improving Photophysical Properties of White Emitting Ternary Conjugated Polymer Blend Thin Film via Additions of TiO2 Nanoparticles

Flexible Candlelight Organic LED on Mica

Effects of Red Light on Circadian Rhythm: A Comparison Among Lamps With Similar Correlated Color Temperatures Yet Distinct Spectrums

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