Since its birth in the laboratory, organic light-emitting diode (OLED) technology has developed into an industry worth tens of billions of dollars in the past three decades. In industrial applications, the phosphorescent materials with 100% exciton utilization efficiency (EUE) have been able to meet the needs of three-primary red and green OLEDs for display. However, the long excited-state lifetime (usually > 1 μs) and high excited-states energy (> 2.8 eV) make blue phosphorescent OLED poorly stable. Therefore, the blue light-emitting materials currently used are still fluorescent materials with a low EUE but short nanosecond excited-state lifetime.
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Source: Phys.org