Long exposure to intensive blue light may damage retina and suppress, at night, melatonin secretion. To devise a blue hazard-free light source with a long lifetime, we demonstrated here a tandem organic light-emitting diode (OLED) with candlelight-style emission, especially via the use of all commercially-available materials. The resultant device shows a color temperature of 1500 K, significantly lower than the 1800 K of oil lamps, 1900 K of candles and 2500 K of incandescent bulbs. It permits, at 100 lx, a retinal exposure-limit of 12 h, while merely 5 min for the 6000 K cold-white LED or CFL. Notably, it is 15 times more human eye-friendly and 30 % more melatonin generation-friendly than the candle. It shows a lifetime of 40,000 h at 1000 cd per meter square, which is about 20,000 times that of a candle and 40 times that of an incandescent bulb. It is 65 times more energy-saving as comparing with candles. Commercially viable human-friendly lighting can be expected in the near future to safeguard human health.

长时间暴露在强蓝光下可能会损伤视网膜并抑制夜间褪黑激素的分泌。为了设计一种使用寿命长的蓝色无害光源，我们在这里展示了一种具有烛光式发射的串联有机发光二极管 (OLED)，特别是通过使用所有市售材料。最终设备的色温为 1500 K，明显低于油灯的 1800 K、蜡烛的 1900 K 和白炽灯泡的 2500 K。它允许在 100 lx 下，视网膜暴露极限为 12 小时，而对于 6000 K 冷白光 LED 或 CFL，则仅为 5 分钟。值得注意的是，它比蜡烛对人眼友好 15 倍，对褪黑激素生成友好 30%。它显示每平方米 1000 cd 的寿命为 40,000 小时，大约是蜡烛的 20,000 倍和白炽灯泡的 40 倍。与蜡烛相比，节能65倍。在不久的将来，商业上可行的人性化照明有望保护人类健康。