Novel Pyrimidine‐Based Iridium Complexes with Bulky Charge‐Carrier Groups as Dopants for Highly Efficient Green Polymer Light‐Emitting Diodes

Abstract

AbstractTwo new pyrimidine‐based iridium complexes with triphenylamine and tetraphenylsilane, namely (TPAPr)2IrAcac and (TPSPr)2IrAcac, were fully synthesized and characterized. Both of the targeted iridium complexes exhibit excellent thermal stability and high photoluminescence quantum yields. Compared to (TPAPr)2IrAcac, (TPSPr)2IrAcac achieved its highest PLQY and current efficiency (CE) at higher dopant concentration probably because of its bulky tetraphenylsilane group, which can effectively suppress the concentration quenching. However, according to DFT studies, (TPSPr)2IrAcac shows faster non‐radiative transitions due to the presence of more excited‐state distortions than (TPAPr)2IrAcac. As a result, Green phosphorescent polymer light‐emitting diodes (PLEDs) containing (TPAPr)2IrAcac and (TPSPr)2IrAcac as dopants exhibit exceptional device performance with peak CE values of 38.24 and 36.06 cd A−1, respectively. (TPAPr)2IrAcac exhibited a superior efficiency than (TPSPr)2IrAcac because of its high Φp, low RMSD value, and efficient energy transfer from the host to the guest. More importantly, the PLEDs based on (TPAPr)2IrAcac and (TPSPr)2IrAcac show stable phosphorescent emission with Commission Internationale de L'Eclairage (CIE) coordinates of (0.313, 0.497) and (0.299, 0.483), respectively. This work points out a viable method for creating phosphorescent iridium complexes based on pyrimidine for high‐efficiency organic light‐emitting diodes (OLEDs).