Carbazole-Based Self-Assembled Monolayer Enabling High-Efficiency Candlelight Organic Light-Emitting Diodes

Excessive blue light exposure might severely threaten retinal health and disrupt circadian rhythms. To mitigate these hazards, candlelight-style sources were developed; however, fabricating high-efficiency, large-area, wet-processed candlelight organic light-emitting diodes (OLEDs) remains challenging. This study demonstrates a high-efficiency, blue-light-free candlelight OLED fabricated via wet process by incorporating a [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer between hole injection and emissive layers. At 1000 cd/m2, the resultant power efficacy, current efficiency and external quantum efficiency can be increased by 22%, 15% and 12%, respectively. Notably, at a high luminance of 10,000 cd/m2, the corresponding efficiencies remain enhanced by 34%, 22%, and 19%, respectively. This device exhibits a color temperature of 1991 K, permitting at 100 lx a maximum exposure limit of 71,211 s, 130 times longer than a cold-white OLED. The enhancement of device efficiencies may be attributed to the reduction in hole injection resistance and the suppression of non-radiative electron leakage.