Fuzzy-junction organic light-emitting devices.

A "fuzzy-junction" organic light-emitting device (OLED) containing a graded organic-organic interface is reported. Such graded junction is effectively produced utilizing interdiffusion through an ultrathin interfacial fusing layer sandwiched between two functional layers. With a glass transition temperature (T[sub g]) lower than remaining layers, this fusing layer permits smooth interdiffusion and mixing of neighboring layers by annealing above its T[sub g]. With appropriate material combinations, fuzzy-junction OLEDs thus prepared exhibit both reduced voltage and enhanced emission efficiency in comparison with conventional abrupt-junction devices. As an instance, a green fluorescent OLED with such fuzzy junction shows a high peak power efficiency of ∼20 lm/W, substantially higher than ∼14 lm/W of a corresponding abrupt-junction device. A "fuzzy-junction" organic light-emitting device (OLED) containing a graded organic-organic interface is reported. Such graded junction is effectively produced utilizing interdiffusion through an ultrathin interfacial fusing layer sandwiched between two functional layers. With a glass transition temperature (T[sub g]) lower than remaining layers, this fusing layer permits smooth interdiffusion and mixing of neighboring layers by annealing above its T[sub g]. With appropriate material combinations, fuzzy-junction OLEDs thus prepared exhibit both reduced voltage and enhanced emission efficiency in comparison with conventional abrupt-junction devices. As an instance, a green fluorescent OLED with such fuzzy junction shows a high peak power efficiency of ∼20 lm/W, substantially higher than ∼14 lm/W of a corresponding abrupt-junction device. [ABSTRACT FROM AUTHOR]