An efficient solid-solution crystalline organic light-emitting diode with deep-blue emission

Crystalline organic semiconductors are potentially attractive media for advanced organic solid-state light-emitting devices due to their advantageous highly oriented transition dipole moments and high mobility of charge carriers, which should in principle lead to efficient light emission; however, crystalline organic semiconductor-based organic light-emitting diodes (C-OLEDs) have until now struggled with poor device performance. Here we report a method to create high-performance C-OLEDs by using organic solid-solution thin films of deep-blue fluorescent materials. Our C-OLED exhibits a strong photon output capacity and has an external quantum efficiency of up to 6.5% with Commission Internationale de L’Eclairage (CIE) colour coordinates of around (0.15, 0.07). The driving voltage (4.0 V@1,000 cd m – 2 ), power efficiency (3.9 lm W –1 @1,000 cd m – 2 ) and series-resistance joule-heat loss ratio (11.1%@1,000 cd m – 2 ) outperform deep-blue amorphous OLEDs (CIE y ≤ 0.08), making it an attractive approach for next-generation OLED technologies.