Candles emit sensationally warm light with a very low color temperature, comparatively most suitable for use at night. In response to the need for such a human-friendly night light, we demonstrate the employment of a high number of candlelight complementary organic emitters to generate and mimic candlelight based on organic light emitting diode (OLED). One resultant candlelight style OLED shows a very-high color rendering index (CRI), with an efficacy at least 300 times that of a candle or at least two times that of an incandescent bulb. The device can be fabricated, for example, by using four candlelight complementary emitters: red, yellow, green, and sky-blue phosphorescent dyes. These dyes, in the present system, can be vacuum deposited into two emission layers that are separated by a nanolayer of carrier modulation material that is used to maximize very high CRI and energy efficiency. A nano carrier modulation layer also played a significant role in maintaining the low blue emission and high-red emission, the low color temperature of device was obtained. Importantly, a romantic sensation giving and supposedly physiologically friendly candlelight style emission can hence be driven by electricity in lieu of hydrocarbon burning and greenhouse gas-releasing candles that were invented 5000 years ago.
Candles emit sensationally-warm light with a very-low color-temperature, comparatively most suitable for use at night. In response to the need for such a human-friendly night light, we demonstrate the employment of a high number of candle light complementary organic emitters to generate mimic candle light based on organic light emitting diode (OLED). One resultant candle light-style OLED shows a very-high color rendering index, with an efficacy at least 300 times that of candles or twice that of an incandescent bulb. The device can be fabricated, for example, by using four candle light complementary emitters, namely: red, yellow, green, and sky-blue phosphorescent dyes, vacuum-deposited into two emission layers, separated by a nano-layer of carrier modulation material to maximize both the desirable very-high color rendering index and energy efficiency, while keeping the blue emission very low and red emission high to obtain the desirable low color temperature. With different layer structures, the OLEDs can also show color tunable between that of candle light and dusk-hue. Importantly, a romantic sensation giving and supposedly physiologically-friendly candle light-style emission can hence be driven by electricity in lieu of the hydrocarbon-burning and greenhouse gas releasing candles that were invented 5,000 years ago.
Color temperature (CT) of light has great effect on human physiology and psychology, and low CT light, minimizing melatonin suppression and decreasing the risk of breast, colorectal, and prostate cancer. We demonstrates the incorporation of a blend carrier modulation interlayer (CML) between emissive layers to improve the device performance of low CT organic light emitting diodes, which exhibits an external quantum efficiency of 22.7% and 36 lm W<sup>-1</sup> (54 cd A<sup>-1</sup>) with 1880 K at 100 cd m<sup>-2</sup>, or 20.8% and 29 lm W<sup>-1</sup> (50 cd A<sup>-1</sup>) with 1940 K at 1000 cd m<sup>-2</sup>. The result shows a CT much lower than that of incandescent bulbs, which is 2500 K with 15 lmW<sup>-1</sup> efficiency, and even as low as that of candles, which is 2000 K with 0.1 lmW<sup>-1</sup>. The high efficiency of the proposed device may be attributed to its CML, which helps effectively distribute the entering carriers into the available recombination zones.
Numerous medical research studies reveal intense white or blue light to drastically suppress at night the secretion of
melatonin (MLT), a protective oncostatic hormone. Lighting devices with lower color-temperature (CT) possess lesser
MLT suppression effect based on the same luminance, explaining why physicians have long been calling for the
development of lighting sources with low CT or free from blue emission for use at night to safeguard human health. We
will demonstrate in the presentation the fabrication of OLED devices with very-low CT, especially those with CT much
lower than that of incandescent bulbs (2500K) or even candles (2000K). Without any light extraction method, OLEDs
with an around 1800K CT are easily obtainable with an efficacy of 30 lm/W at 1,000 nits. To also ensure high
color-rendering to provide visual comfort, low CT OLEDs composing long wavelength dominant 5-spectrum emission
have been fabricated. While keeping the color-rendering index as high as 85 and CT as low as 2100K, the resulting
efficacy can also be much greater than that of incandescent bulbs (15 lm/W), proving these low CT OLED devices to be
also capable of being energy-saving and high quality. The color-temperature can be further decreased to 1700K or lower
upon removing the undesired short wavelength emission but on the cost of losing some color rendering index. It is hoped
that the devised energy-saving, high quality low CT OLED could properly echo the call for a physiologically-friendly
illumination for night, and more attention could be drawn to the development of MLT suppression-less non-white light.
Highly efficient organic light-emitting diodes (OLEDs) are strongly demanded for both display and illumination applications. High efficiency would also help prolong the device lifespan. However, many OLEDs encounter significant roll-off problems, leading to undesired low device efficiency at high luminance, which is unfavorable to their commercial realization for lighting. Hence, OLED devices with mild or even little roll-off are highly expected. We have, nevertheless, observed some OLEDs that exhibit roll-up phenomenon, i.e., that their external quantum efficiency (EQE) or current efficiency increases as the applied voltage or brightness is increased. By taking such advantage of device architecture design, OLEDs with an approaching or even above the theoretical limit EQE are obtained at high luminance. In this report, we present how this works for a yellow OLED that exhibits a record-high power efficiency among reported fluorescent yellow OLEDs, a very-low color temperature OLED with a record-breaking efficacy based on the same color-temperature, and a green OLED. Notably, the yellow OLED exhibits an EQE that increases from 5.4 to 6.2% and current efficiency from 16.4 to 18.7 cd/A as the luminance increases from 1000 to 10,000 cd/m2. Plausible mechanisms regarding why roll-up occurs in these devices are discussed.
Light sources with low color temperature (CT) are essential for their markedly
less suppression effect on the secretion of melatonin, and high power efficiency is crucial
for energy-saving. To provide visual comfort, the light source should also have a
reasonably high color rendering index (CRI). In this report, we demonstrate the design
and fabrication of low CT and high efficiency organic light-emitting diodes. The best
resultant device exhibits a CT of 1,880 K, much lower than that of incandescent bulbs
(2,000-2,500 K) and even as low as that of candles, (1,800-2,000 K), a beyond theoretical
limit external quantum efficiency 22.7 %, and 36.0 lm/W at 100 cd/m <sup>2</sup>. The high
efficiency of the proposed device may be attributed to its interlayer, which helps
effectively distribute the entering carriers into the available recombination zones.
We demonstrate organic light-emitting diodes (OLEDs) capable of yielding sunlight-style illumination with various daylight chromaticities, whose color temperature (CT) covers those of the daylight at different times and regions. Besides having the disruptive characters like being plane-type and luminaire-ready, flexible, printable, thin, and light, the emissive spectrum of OLEDs closely resembles that of sunlight. The degree of sunlight spectrum resemblance is 63%, for example, for one high color rendering OLED, while 2% for a sodium lamp, 16% for a fluorescent tube, 49% for a light-emitting diode, and 72% for an incandescent bulb. By incorporating one hole-modulating layer (HML), a fluorescent sunlight-style OLED yields CT between 2300 and 7900 K, while the CT span can be further expanded between 2400 and 18000 K by using double HMLs. For a phosphorescent sunlight-style OLED, the CT spans between 1900 and 3100 K with a power efficiency of 17.6 lm/W at 1000 cd/m2.
High-efficiency is strongly desired for organic light-emitting diodes (OLEDs) to be fully realized as the future display
and lighting technology. To replace current illumination tools, such as incandescent bulbs and fluorescent tubes, for
examples, OLEDs with much higher efficiency are demanded. We will present herein some approaches for fabricating
high-efficiency OLEDs of blue and white emission. Besides employing highly efficient electroluminescent guests and
thin device architecture, low injection barriers to carriers, high carrier-transporting character, effective carrier/exciton
confinement, balanced carrier-injection, exciton generation on host, effective host-to-guest energy-transfer and improved
light-coupling efficiency are essential. Amongst, the incorporation of nano-dots in emissive- and non-emissive-layers can
markedly improve the device efficiency. The enhancement is especially marked as small polymeric nano-dots are
incorporated into the non-emissive layers. Since the incorporation is not in the emissive layer, the efficiency
improvement mechanism works for both fluorescent and phosphorescent devices. Importantly, the efficiency
improvement is also a strong function of the surface charge density of the nano-dots. Regardless positively or negatively
charged, the improvement becomes more pronounced as the charge density increases. Results regarding some lately
achieved extraordinarily highly-efficient OLEDs containing nano-dots with high surface charge will be presented.
Long life-time molecular-based organic electronics, such as organic light-emitting diodes (OLEDs), organic solar
cells, or organic transistors etc, inevitably demand their constituent molecules to be highly thermal-stable. Coupling with
special needs in molecular design, the resultant increasing molecular weight (MW) will eventually make the molecules
difficult to deposit if via dry-process, while using wet-process would frequently result in undesired relatively poorer
efficiency. Surprisingly, two high-molecule composing OLEDs with relatively high-efficiency were obtained by using
solution-process. A blue OLED with a blue dye doped in a novel
high-MW, wide band-gap host,
3,5-di(9H-carbazol-9-yl) tetraphenylsilane (SimCP2), yielded 24 lm/W (38 cd/A) at 100 nits, and a green OLED using a novel
high-MW green dye, bis[5-methyl-7-trifluoromethyl-5H-benzo (c)(1,5) naphthyridin-6-one] iridium (picolinate)
(CF3BNO), yielded 70 lm/W (89 cd/A), while their dry-processed blue and green counterparts yield 1.7 and 21 lm/W,
respectively. Importantly, although the comparatively high MW has made the resulting molecules extremely difficult to
vacuum-evaporate and has resulted in poor device performance, the wet-process has been proven effective in fabricating
two high molecule-containing OLEDs with relatively high efficiency. The successful demonstration suggests that the
same approach may as well be extended to other organic devices that compose or should compose high molecules.
High-efficiency fluorescent white organic light-emitting diodes (OLED) were fabricated by using double holetransporting-
layers (HTLs), poly(3,4-ethylene- dioxythiophene)-poly-(styrenesulfonate) (PEDOT) and N,N'-bis-(1-
naphthyl)-N,N'-diphenyl-1,10-biphenyl-4-4'-diamine (NPB). The diodes were composed of a single emissive-layer
(EML), with 0.5 wt% red 4-(dicyanomethylene)-2-tbutyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped in a
mixed-host of 25% trans-1,2-bis(6-(N,N-di-p-tolylamino)-Naphthalene-2-yl)ethene and 75% 1-butyl-9,10-naphthaleneanthracene.
The device structure comprised a 125 nm anode layer of indium tin oxide, a 25 nm first HTL of PEDOT, a 0
to 10 nm second HTL of NPB, a 30 nm EML, a 40 nm electron-transporting-layer of 2,2',2"-(1,3,5-benzenetriyl)-tris(1-
phenyl-1-H-benzimidazole), a 1 nm electron-injection-layer of lithium fluoride and a 150 nm cathode layer of aluminum.
With the addition of a 7.5 nm second HTL (NPB), the resultant power-efficiency at 100 cd/m<sup>2</sup>, for example, was
increased from 11.9 to 18.9 lm/W, an improvement of 59%. The improvement was even more marked at 1,000 cd/m<sup>2</sup>,
i.e. that the power-efficiency was increased from 9.1 to 16.5 lm/W, an improvement of 81%. The marked efficiency
improvement may be attributed to a better balance of carrier-injection in the desired emissive zone since the addition of
the NPB layer in between the first HTL and the EML may have effectively reduced the injection of excessive holes into
the EML due to the relatively high energy-barrier to hole, which was 0.5 eV, at the interface of the two HTLs. The
resultant hole-blocking function was plausibly more effective at higher voltage so that comparatively much less holes
would be injected into the EML, leading to a much better balanced carrier-injection and consequently a higher
efficiency-improvement at the higher brightness.
SiN<SUB>x</SUB> films were prepared by rf reactively sputtering. The refractive index of SiN<SUB>x</SUB> films was affected by total pressure and sputtering power. When the total pressure increased, the refractive index decreased. The reduction of sputtering power showed similar effect to raise the total gas pressure. The residual stress and roughness of SiN<SUB>x</SUB> films depended on the total pressure, sputtering power, and the thickness. The thermal cycles may result in irreversible change of residual stress of SiN<SUB>x</SUB> film. The magnetic properties of TbFeCo depended on the residual stress and roughness of SiN<SUB>x</SUB> in the trilayer SiN<SUB>x</SUB>/TbFeCo/SiN<SUB>x</SUB> samples. The coercivity of TbFeCo was enhanced in the samples with SiN<SUB>x</SUB> films having low stress and large roughness.
Chip-on-film is a new technology after tape-automated- bonding (TAB) and chip-on glass (COG) in the interconnection of liquid crystal module. The thickness of the film, which is more flexible than TAB, can be as thin as 44 micrometers . It has pre-test capability, while COG hasn't. It possesses great potential in many product fabrication applications. In this study, we used anisotropic conductive film as the adhesive to bind the desired IC chip and polyimide film.