市面上大多照明產品都含有大量藍光，然而，藍光會對人體產生危害，甚至提升罹癌風險；因此，為了保護人類生理健康，我們需要一個低藍害或無藍害的照明；類燭光有機發光二極體(OLED) 因其具有低藍害之特性，而成為到目前為止最安全之照明；然而，現今照明產品皆應用於高電流密度操作下，故OLED壽命成為關鍵的問題；在此，本研究提供一種新穎方法，藉由使用堆疊結構並搭配高純度的染料，研製出壽命長達200,000小時的無藍害OLED；其元件電流效率為37.4 cd/A、外部量子效率(EQE)為22.7%、顯色指數(CRI)為80、自然光譜相似性指數(SRI)為78以及壽命(t50)為223,500小時；此外，其視網膜最大可忍受曝光極限(MPE)長達12,300秒 (3.42小時)，並僅含微量的褪黑激素分泌抑制敏感度(MSS 1.7%)，相較於冷白緊湊型螢光燈管(色溫5,921 K, MPE 343秒, MSS 29%)、發光二極體(色溫5,501 K, MPE 316秒, MSS 20%)與OLED(色溫5,000 K, MPE 548, MSS 12%)，由視網膜保護角度來看，分別安全35、38與21倍；從褪黑激素抑制角度來看，分別安全16、11與6倍，可看出此元件具有保護人類健康的特性，並使無藍害OLED成為具有高潛力的照明。

Most of the lighting products on the market contain large blue light, however, blue light will cause harm to the human body and even increase the risk of cancer. Therefore, in order to protect human eyes and physiology, we urgent need a low blue emission or blue hazard free lighting. Candle light-style organic light emitting diode (OLED) is so far the safest measure for its blue hazard free low color temperature illumination. However, lifetime is still the most critical reliability issue in OLEDs, especially in lighting applications that are closely associated with high current density operation. Here, we present a novel approach to develop blue-hazard free OLEDs with a lifetime exceeding 200,000 hours at 1,000 cd/m2 by employing a tandem structure with ultra-high purity emitter. The resultant device shows a current efficacy of 37.4 cd/A, an external quantum efficiency (EQE) of 22.7%, an 80 CRI, and a 78 SRI with a 223,500 hours lifetime (t50). Additionally, the resultant device also exhibits long retina exposure duration of 12,300 s (3.42 h) and suppresses very less melatonin generation (1.7%), compared to cool white compact fluorescent lamps (color temperature 5,921 K, MPE 343 seconds, MSS 29%), light-emitting diodes (color temperature 5,501 K, M PE 316 seconds, MSS 20%) and OLED (color temperature 5,000K, MPE 548 seconds, MSS 12%). From the view of retina protection, the resultant device has 35, 38 and 21 times safer respectively. From the perspective of melatonin suppression, it is respectively safer 16, 11 and 6 times, demonstrating that the fabricated OLED device to be a highly prospective general lighting source to safeguard human health and makes it become a lighting with high potential.

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