Modifying the AIE-TADF chromophore with host-substituents to achieve high efficiency and low roll-off non-doped OLEDs

Abstract In this paper, the periphery of aggregation-induced emission-thermally activated delayed fluorescence (AIE-TADF) chromophore (DPS-PXZ) was modified with host-substituents (DCB, mCP, pPhDCz and mPhDCz). Four self-host TADF emitters, namely DCB-DPS-PXZ, mCP-DPS-PXZ, pPhDCzDPSPXZ and mPhDCzDPSPXZ, were designed and synthesized. Here, the effect of host-substituents with different linking topologies on TADF has been investigated. Among them, the pPhDCz and mPhDCz substituted AIE-TADF emitters have stronger AIE effect than that of DCB and mCP based ones, which due to the larger twist angle between host substituents and DPS-PXZ. And then, mPhDCzDPSPXZ and pPhDCzDPSPXZ could obtain the PLQYs of 56% and 55% in the neat film, respectively. The PLQY values were higher than that of DCB-DPS-PXZ (40%) and mCP-DPS-PXZ (47%). Based on these advantages, the maximum EQE and the efficiency roll-off at 1000 cd/m2 of the non-doped OLEDs were 18.1% and 7.7% for mPhDCzDPSPXZ, 17.1% and 9.9% for pPhDCzDPSPXZ, respectively. However, the maximum EQEs of DCB-DPS-PXZ and mCP-DPS-PXZ based non-doped devices were only 13.9% and 14.7%, respectively. Therefore, the careful modification of the AIE-TADF chromophore by changing host-substituent types and linking positions appropriately was beneficial for the realization of efficient and low efficiency roll-off non-doped OLEDs.