Highly Efficient Non‐Doped Blue Organic Light‐Emitting Diodes Based on Fluorene Derivatives with High Thermal Stability

Abstract A new series of blue‐light‐emitting fluorene derivatives have been synthesized and characterized. The fluorene derivatives have high fluorescence yields, good thermal stability, and high glass‐transition temperatures in the range 145–193 °C. Organic light‐emitting diodes (OLEDs) fabricated using the fluorene derivatives as the host emitter show high efficiency (up to 5.3 cd A –1 and 3.0 lm W –1 ) and bright blue‐light emission (Commission Internationale de L'Eclairage (CIE) coordinates of x = 0.16, y = 0.22). The performance of the non‐doped fluorene‐based devices is among the best fluorescent blue‐light‐emitting OLEDs. The good performance of the present blue OLEDs is considered to derive from: 1) appropriate energy levels of the fluorene derivatives for good carrier injection; 2) good carrier‐transporting properties; and 3) high fluorescence efficiency of the fluorene derivatives. These merits are discussed in terms of the molecular structures.