An effective approach for making solution-processable deep blue emitters via side chain modification

Abstract

Efficient solution-processable blue materials play a key role in promoting low-cost commercial application of organic light emitting devices (OLEDs). In this report, we have designed and synthesized three novel solution-processable organic blue emitters, denoted as LDT1, LDT2, and LDT3, based on a ladder-type oligo(p-phenylene)s skeleton. Through varying the chains at the para-position of their lateral benzene rings, their solubility can be tuned. Experimental and theoretical results show a high degree of similarity in energy levels, photo-physical properties, and molecular conformation for three compounds. Their solution processed devices achieve deep blue emission with their Commission Internationale de l’Eclairage coordinates locating at (0.155, 0.073), (0.153, 0.069), and (0.156, 0.080), and their EL spectra peaked at 428 nm. The corresponding maximum external quantum efficiency (EQE) for LDT1, LDT2, and LDT3 are 1.24%, 1.64%, 1.24%, respectively. These findings provide valuable guidance for making solution-processable deep blue emitters based on the side chains modification.