Transparent Flexible Candlelight OLED

Excessive exposure to intense blue light could harm retina and disrupt melatonin secretion at night. To solve, a blue light-less candlelight organic light-emitting diode (OLED) was invented in 2012, a festive replacement of hydrocarbon-burning candles. Incorporating further flexibility and transparency could create design freedom and expand its applicability. We demonstrate herein a successful fabrication of a transparent candlelight OLED on a flexible mica. When unpowered, this device exhibits 40% transmittance. Upon applying voltage, both the top and bottom emissions of the device exhibit blue-hazard-free candlelight with a color temperature of 1800 K, which remain unaffected by bending. From retinal protection perspective, the resulting 1800 K color temperature permits, at 100 l×, an exposure limit of 54,900 s, while 404 s for a 4000 K yellow-white counterpart. Upon exposure at night for 1.5 h, it would only suppress 2% melatonin, in contrast of 13% by the yellow-white light. We anticipate this research to open a path for fabricating OLEDs which are transparent, flexible, and omni-friendly.