Rigid DOBNA-Based Host Engineering for Efficient Energy Transfer and Long-Lifetime Red Solution-Processed OLEDs

Aggregation-Controlled Design of Rigid DOBNA-Based Host Materials for Long-Lifetime Red Solution-Processed OLEDs

Solution-processed OLEDs (s-OLEDs) offer advantages in low-cost and large-area fabrication, but their practical application is limited by poor operational stability caused by molecular aggregation and exciton quenching. In this work, two indacene-based bipolar host materials, DITI-QSi and DITI-tDOBNA, were designed to investigate the influence of molecular rigidity on device performance.

DITI-tDOBNA incorporates a rigid DOBNA acceptor with steric hindrance, effectively suppressing molecular aggregation and intramolecular motion compared with the flexible DITI-QSi host. As a result, DITI-tDOBNA exhibited enhanced photoluminescence quantum yield, improved charge balance, and more efficient Förster and Dexter energy transfer within the emitting layer.

Red phosphorescent s-OLEDs based on DITI-tDOBNA achieved a maximum current efficiency of 25.1 cd A⁻¹ and an external quantum efficiency of 18.6%. More importantly, the device demonstrated a significantly improved operational lifetime (LT50) of approximately 1400 h. These results highlight the importance of molecular rigidity and aggregation control in the design of high-performance and long-lifetime host materials for solution-processed OLEDs.