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.
