The authors would like to acknowledge the support in part from the Ministry of Economic Affairs and the Ministry of Science and Technology, Taiwan, via Grants MEA 104-EC-17-A-07-S3-012, MOST 104-2119-M-007-012, and MOST 103-2923-E-007-003-MY3.

NOTE: All the materials used are non-carcinogenic, non-flammable, and non-toxic.
1. Fabrication of Blue-hazard-free Candlelight OLED
<ol>
	<li>Dry process
	<ol>
		<li>Take a glass slide as a substrate to be coated with a 125 nm indium tin oxide (ITO) anode layer. Wash the substrate with 200 mL (50 mL of liquid detergent and 150 mL of deionized water) of soap solution. Rinse the substrate with deionized water. Dry the substrate with a nitrogen jet spray.</li>
		<li>Put the substrate on a glass sl...

<ol>
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Electron. 13 (8), 1349-1355 (2012).</li><li>Jou, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Candlelight-style+organic+light-emitting+diodes.">Candlelight-style organic light-emitting diodes.</a> Adv. Funct. Mater. 23 (21), 2750-2757 (2013).</li><li>Jou, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=OLEDs+with+chromaticity+tunable+between+dusk-hue+and+candle-light.">OLEDs with chromaticity tunable between dusk-hue and candle-light.</a> Org. Electron. 14 (1), 47-54 (2013).</li><li>Hu, Y., Zhang, T., Chen, J., Ma, D., Cheng, C. 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We have nothing to disclose.

The most critical steps in the fabrication of OLED devices are: 1) cleaning the glass substrate, 2) selecting the appropriate solvent, 3) dissolving the organic materials, 4) uniformly forming the film via spin-coating in the wet process, and 5) controlling the deposition rate and thickness of the organic layer during the thermal evaporation. Initially, cleaning the ITO anode coated substrate is a crucial step to achieve high efficiency. The glass substrate is cleaned with soap solution to remove greasy spots or layers. ...

Nowadays, lighting sources like LED and CFL are abundantly used for indoor and outdoor illumination, partly for energy-saving reasons. However, these lights are rich in blue emission, showing a higher tendency to cause blue-hazards. LED and CFL emit a spectrum enriched with blue light, leading to irreversible damage to retinal cells1,2,3,4. Blue light or intense white light with high CCT suppresses the secretion of melatonin, an oncostatic hormone, which may disrupt the circadian rhythm5,6 and sleeping behavior7,8. Melatonin, an essential hormone for the circadian rhythm, is synthesized in the pineal gland9. A high level of melatonin is observed during the dark period during the 24-h light-dark cycle10. However, intensive light at night suppresses its synthesis and disrupts the circadian rhythm11. Melatonin suppression due to overexposure to bright lights at night can be a risk factor for breast cancer in women12,13,14. Besides these hazards, blue light interrupts the activities of nocturnal amphibians and can be threatening to ecological protection. It has also been reported that LED lighting in museums is discoloring the actual colors of oil paintings painted by Van Gogh and C&#233;zanne15,16.
Thus, a blue-emission free and low CCT candle-like organic LED (OLED) can be a good substitute for LED and CFL. Candles emit a blue-hazard-free and low CCT (1,914 K) illumination, as well as a high-quality (high color rendering index, CRI) emission spectrum. However, most of the electricity-driven lighting devices emit intense blue light with a comparatively high CCT. For example, the lowest CCT is about 2,300 K for incandescent bulbs, while it is 3,000 or 5,000 K for warm or cold white fluorescent tubes and LED luminaires. So far, low CCT OLEDs nearly free of the blue emission have been fabricated for human-friendly lighting. In 2012, Jou&#39;s group reported a physiologically friendly, dry-processed, single emissive layer OLED with a CCT of 1,773 K and a power efficiency of 11.9 lm/W17. The device exhibited a much lower CCT as compared to the incandescent bulb (2,300 K), while its power efficiency was not acceptable from an energy-saving point of view. They reported another dry-processed candlelight-style OLED by using double emissive layers along with a carrier modulation layer18. It exhibited a low CCT of 1,970 K and a power efficiency of 24 lm/W. Later on, a dry-processed OLED consisting of three emissive layers along with a carrier modulation layer was reported19. Its power efficiency was from 21 to 3 lm/W and varied with the CCT, which ranged from 2,500 K to 1,900 K. In 2014, Hu et al. reported a dry-processed hybrid OLED with double emissive layers separated by an interlayer, which showed a high power efficiency of 54.6 lm/W and a low CCT of 1,910 K20. Recently, Jou&#39;s group has fabricated a high-efficiency candlelight-style OLED by employing double emissive layers21. It exhibited a high power efficiency of 85.4 lm/W with a CCT of 2,279 K. Until now, all efforts have been made to develop high efficiency, low CCT candlelight-style OLED devices by utilizing dry processes and complicated device architectures17,18,19,20,21,22. Devising a candlelight OLED with wet-process feasibility while simultaneously having a low CCT, a high power efficiency, and a high light quality is a challenge. No study has been developed to describe the emission spectrum sensitivity of a given light source with respect to the blue light. The quality of light at night can be decided/improved to minimize the suppression of melatonin secretion.
There are some reported models that calculate the amount of suppression. Firstly, Brainard et al.23 and Thapan et al.24 reported the spectral sensitivity by using monochromatic light. Later on, the effect of polychromatic light on melatonin suppression was described25,26. The latter is adopted in this study, since most of the commercially available luminaires or novel lighting sources are polychromatic and span over the entire visible range (i.e., from deep red to violet).
In this work, we present comprehensive protocols for the fabrication of blue-hazard-free candlelight OLEDs via dry and wet processes. In both processes, the device architecture is simplified by employing a single emissive layer without any carrier modulation layers. The electroluminescent (EL) spectrum of the fabricated OLED is analyzed for the retinal exposure limit and for the level of melatonin secretion suppression. A maximum exposure limit of emitted light to the retina is calculated by using the theoretical aspect that was reported by the International Electrotechnical Commission (IEC) 62471 standard27,28. The maximum exposure limit &#34;t&#34; is calculated by using the emission spectrum of each OLED at the brightness of 100 and 500 lx, sufficient for home and office illumination, respectively. All related calculation steps are sequentially given in the protocol section. Further, the effect of lighting on the melatonin suppression sensitivity is calculated by following the equations of the action spectrum of melatonin suppression29. The calculation is done by following the steps given in the protocol section. The calculated values of the maximum exposure limit &#34;t&#34; and the melatonin suppression sensitivity (%) with respect to CCT are given in Table 3.

<table border="0" cellpadding="0" cellspacing="0" width="1081">
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		<col />
		<col />
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	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">ITO glass</td>
			<td style="width:311px;">Lumtech</td>
			<td style="width:80px;"></td>
			<td dir="LTR" style="width:128px;">84% transparency</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">poly(3,4-ethylenedioxythiophene)-&#160; poly(styrenesulfonate)&#160; (PEDOT/PSS)</td>
			<td style="width:311px;">UniRegion Bio-Tech</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Stored at 4&#176;C, HOMO (eV)= -4.9, LUMO (eV)= -3.3</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">&#160;4,4,4-tris(N-carbazolyl)triphenylamine (TCTA)</td>
			<td style="width:311px;">E-Ray Optoelectronics Technology co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Non-toxic, HOMO (eV)= -5.7, LUMO (eV)= -2.3</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">&#160;tris(2-phenyl-pyridine) (Ir(ppy)3)&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:311px;">E-Ray Optoelectronics Technology co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Non-toxic, HOMO (eV)= -5.6, LUMO (eV)= -3.9</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">&#160;1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene&#160; (TPBi)</td>
			<td style="width:311px;">Luminescence Technology corp.</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Non-toxic, HOMO (eV)= -6.2, LUMO (eV)= -2.7</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:563px;">iridium(III)bis(4-phenylthieno[3,2-c]pyridinato-N,C 2&#8217;)acetylacetonate (PO-01)</td>
			<td style="width:311px;">Luminescence Technology corp.</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Non-toxic, HOMO (eV)= -5.1, LUMO (eV)= -2.7</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">&#160;tris(2-phenylquinoline)iridium(III) (Ir(2-phq)3)</td>
			<td style="width:311px;">E-Ray Optoelectronics</td>
			<td style="width:80px;"></td>
			<td dir="LTR">Non-toxic, HOMO (eV)= -5.1, LUMO (eV)= -2.8</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">LiF</td>
			<td style="width:311px;">Echo chemicals</td>
			<td style="width:80px;"></td>
			<td dir="LTR">99.98%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Aluminium ingot (Al)</td>
			<td style="width:311px;">Guv team International pvt. ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">100.00%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Acetone</td>
			<td style="width:311px;">Echo chemicals</td>
			<td style="width:80px;"></td>
			<td dir="LTR">99.90%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">2-Propanol</td>
			<td style="width:311px;">Echo chemicals</td>
			<td style="width:80px;"></td>
			<td dir="LTR">99.90%</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:563px;">Hole-injection material, WHI-001</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -9.8, LUMO (eV)= -5.6</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Hole-transport material, WHI-215</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -5.4, LUMO (eV)= -2.5</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">&#160;host material, WPH-401</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -5.8, LUMO (eV)= -2.7</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Electron-injection material, WIT-651</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -5.8, LUMO (eV)= -3.1</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Electron-transpot material, WET-603</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -5.9, LUMO (eV)= -2.6</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Green dye, WPGD-832</td>
			<td style="width:311px;">WAN HSIANG precision machinery co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non-toxic, HOMO (eV)= -5.8, LUMO (eV)= -3.1</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:563px;">Deep-red dye, PER 53</td>
			<td style="width:311px;">E-Ray Optoelectronics Technology co., Ltd</td>
			<td style="width:80px;"></td>
			<td dir="LTR">non toxic, HOMO (eV)= -5.1, LUMO (eV)= -2.4</td>
		</tr>
	</tbody>
</table>

blue-hazard-free candlelight oled

A candlelight-style organic light emitting diode (OLED) is a human-friendly type of lighting because it is blue-hazard-free and has a low correlated color temperature (CCT) illumination. The low CCT lighting is deprived of high-energy blue radiation, and it can be used for a longer duration before causing retinal damage. This work presents the comprehensive protocols for the fabrication of blue-hazard-free candlelight OLEDs. The emission spectrum of the OLED was characterized by the maximum exposure time limit of the retina and the melatonin suppression sensitivity. The devices can be fabricated using dry and wet processes. The dry-processed OLED resulted in a CCT of 1,940 K and exhibited a maximum retinal exposure limit of 1,287 s at a brightness of 500 lx. It showed 2.61% melatonin suppression sensitivity relative to 480 nm blue light. The wet-processed OLED, where the spin coating is used to deposit hole injection, hole transport, and emissive layers, making fabrication fast and economical, produced a CCT of 1,922 K and showed a maximum retinal exposure limit of 7,092 at a brightness of 500 lx. The achieved relative melatonin suppression sensitivity of 1.05% is 86% and 96% less than that of the light emitting diode (LED) and compact fluorescent lamp (CFL), respectively. Wet-processed blue-hazard-free candlelight OLED exhibited a power efficiency of 30 lm/W, which is 2 times that of the incandescent bulb and 300 times that of the candle.

The current-voltage-luminance characteristics of the resulting candlelight OLEDs are measured by using an electrometer together with a 100 A luminance meter. The emission areas are 9 mm2 for all of the resulting dry-processed devices and are 25 mm2 for wet-processed devices. Here, we used a 125 nm ITO-coated glass substrate with a sheet resistance of 15 &#937;/sq as an anode. It has a transparency greater than 84% (Table 4). All the OLED devices cons...

Watch this Scientific Journal Video about Blue-hazard-free Candlelight OLED at JoVE.com

Blue-hazard-free Candlelight OLED

We present a protocol for the fabrication of a blue-hazard-free candlelight organic light emitting diode (OLED) for eye protection and melatonin secretion.

A candlelight-style organic light emitting diode (OLED) is a human-friendly type of lighting because it is blue-hazard-free and has a low correlated color ...

The overall goal of this protocol is to fabricate a blue hazard free lighting source candlelight OLED and to quantify the blue hazards using melatonin suppression sensitivity and maximum permissible retina exposure limit. This protocol can help answer key questions in the lighting field, such as how you quantify the blue hazard of a given light and how to fabricate a blue hazard free light source. The main advantage of this protocol is that one can readily estimate the threat of a given light source and prevent the possible damages.Though this approach can provide insight into healthy illumination, it can also be applied to display systems such as LCD and OLED TVs. We first had this idea for this approach when we found that candlelight OLED is quite blue hazard free and shows high light quality. To begin the dry fabrication procedure, wash a glass slide coated with 125 nanometer ITO anode layer, with 200 milliliters of soap solution.Rinse the washed slide with deionized water. Next, dry with a nitrogen jet spray. Put the slide on a glass slide holder.Then, dip the slide holder into a beaker containing acetone. Place the beaker into an ultrasonic bath and sonicate for 10 minutes at 50 degrees Celsius. After this, transfer the slide holder to a beaker containing isopropanol.Sonicate for 10 minutes at 60 degrees Celsius. Place the slide in a UV ozone slot for 10 minutes to dry. Then clean the surface completely.At the thermal evaporator chamber, close the valve of the high vacuum. Next, open the nitrogen gas valve. Load the cleaned glass slide to the rotating holder in the evaporator chamber.Then, add the required materials to the chamber's crucibles as outlined in the text protocol. After this, close the chamber door. Close the nitrogen gas valve and open the high vacuum valve.Once the pressure in the chamber has reached a high vacuum, five time 10 to the negative six torr, deposit organic layers onto the glass slide as outlined in the text protocol. After the layers have been deposited, turn off the current controller. And allow the fabricated OLED device to sit for 10 minutes under high vacuum.Next, close the high vacuum valve and open the nitrogen gas valve to break the chamber's vacuum. Remove the OLED device from the chamber. Then, transfer the device to a glove box with an encapsulation machine under a nitrogen atmosphere.Using glue, encapsulate the device with a glass top cover. Place the device in a UV radiation box for 110 seconds to dry the glue. After this, transfer the device to the darkroom and perform measurements as outlines in the text protocol.To begin the wet fabrication procedure, use a slide holder to dip an ITO coated slide into a beaker of acetone. Sonicate the beaker for 10 minutes at 50 degrees Celsius. Next, transfer the slide holder to a beaker of isopropanol.Sonicate for 10 minutes at 60 degrees Celsius. Place the slide into the UV ozone slot for 10 minutes to dry, then clean the surface completely. Using a 25 millimeter diameter nylon fabric filter with a pour size of 45 micrometers filter an aqueous PEDOT:PSS solution into a vial.In a separate vial, prepare a VPEC solution as outlined in the text protocol. Place the vial in an ultrasonic bath at room temperature and sonicate for 30 minutes. Then, using a 15 millimeter diameter nylon fabric filter with a pour size of 45 micrometers, filter the solution into a fresh vial.Next, sonicate the prepared host material and guest material solutions for 30 minutes at 50 degrees C.Use a 15 millimeter nylon fabric filter with a 45 micrometer pour size to filter each solution separately into a fresh vial. After this, mix the guest solution into the host solution according to the given weight percent detailed in the text protocol. Transfer the vial of resulting emissive layer solution along with the vial of PEDOT:PSS solution and vial of VPEC solution into the glove box.Then, move the pre-cleaned ITO coated slide into the glove box. Posit the hold injection layer, hold transport layer, and emissive layer as outlined in the text protocol. Once the layers have been deposited, move the slide from the glove box.At the thermal evaporator chamber, close the valve of the high vacuum and open the nitrogen gas valve to break the chamber's vacuum. Then load the layered slide into the chamber's rotating holder. Next, add 45 milligrams of TPBi.Three milligrams of lithium fluoride, and 224 milligrams of aluminum to the chamber's crucibles. Deposit the electron transport layer, the electron injection layer, and cathode layer as detailed in the text protocol. After this, turn off the current controller, let the fabricated OLED device sit for 10 minutes under high vacuum.Break the chamber's vacuum and remove the device. Next, transfer the device to a glove box with an encapsulation machine under a nitrogen atmosphere. Use glue to encapsulate the device with a glass top cover.Place the device in a UV radiation box for 110 seconds to dry the glue. Then, transfer the device to the darkroom and perform measurements as outlined in the text protocol. In this study, blue hazard free candlelight OLEDs are fabricated using both dry and wet processes.The effects of the correlated color temperature of these devices on the retinal exposure limit are shown here. At 500 lux, all of the studied OLED devices show exposure limits with a risk group of RG1. However, by reducing the illumination to 100 lux, the exposure limit increases five times, and the devices that exhibit a correlated color temperature below 1, 940 Kelvin shift their exposure limits to RG0.The effects of the correlated color temperature of the fabricated OLED devices on melatonin suppression sensitivity are then determined. While standard warm white LEDs suppress melatonin secretion by approximately 8%all the fabricated OLEDs show a suppression of less than 4%Therefore, these blue hazard free candlelight OLEDs which exhibit a very low suppression effect, can be used at night without greatly disturbing the secretion of melatonin. Once mastered, the calculation can be done in an hour or less, and the fabrication can be done in seven hours if performed properly.While attempting this fabrication, it is important to carefully clean the substrate and control the deposition rate to achieve best performance of the device. This technique we hope pave the way for researchers in the lighting and display fields to explore blue hazard free healthy light. After watching this video, you should have a good understanding regarding how to quantify the blue hazards of any given light source and how to fabricate a blue hazard free candlelight OLED.Do not forget to a separator and hand gloves while working around the evaporator chamber. Solvents like tetrahydrofuran and chlorobenzene can be hazardous, and precautions such as carbon face mask should always be taken while performing this procedure.

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9.2K visualizações.  National Tsing Hua University. The overall goal of this protocol is to fabricate a blue hazard free lighting source candlelight OLED and to quantify the blue hazards using melatonin suppression sensitivity and maximum permissible retina exposure limit. This protocol can help answer key questions in the lighting field, such as how you quantify the blue hazard of a given light and how to fabricate a blue hazard free light source. The main advantage of this protocol is that one can readily estimate the threat of a given light...