Stable, Glassy, and Versatile Binaphthalene Derivatives Capable of Efficient Hole Transport, Hosting, and Deep-Blue Light Emission

Organic light-emitting diodes (OLEDs) have great potential applications in display and solid-state lighting. Stability, cost, and blue emission are key issues governing the future of OLEDs. The synthesis and photoelectronics of a series of three kinds of binaphthyl (BN) derivatives are reported. BN1-3 are melting-point-less and highly stable materials, forming very good, amorphous, glass-like films. They decompose at temperatures as high as 485-545 degrees C. At a constant current density of 25 mA cm(-2), an ITO/BN3/Al single-layer device has a much-longer lifetime (>80 h) than that of an ITO/NPB/Al single-layer device (8 h). Also, the lifetime of a multilayer device based on BN1 is longer than a similar device based on NPB. BNs are efficient and versatile OLED materials: they can be used as a hole-transport layer (HTL), a host, and a deep-blue-light-emitting material. This versatility may cut the cost of large-scale material manufacture. More importantly, the deep-blue electroluminescence (emission peak at 444 nm with CIE coordinates (0.16, 0.11), 3.23 cd A(-1) at 0.21 mA cm(-2), and 25200 cd m(-2) at 9 V) remains very stable at very high current densities up to 1000 mA cm(-2).