Benzothiadiazole based hot exciton'' materials for red electroluminescence with the maximum external quantum efficiency approaching 10%

To achieve high exciton utilization of organic light-emitting diodes, the construction of donor-acceptor (D-A) molecules with a hot exciton feature has been proved to be an effective strategy. Herein, two novel benzothiadiazole based D-A-D ' type hot exciton materials, TPA-BT-PBI and TPA-BT-IM, have been designed and synthesized for red OLEDs. The TPA-BT-PBI and TPA-BT-IM based non-doped devices exhibit maximum external quantum efficiency (EQE(max)) values of 2.78% and 5.11%, respectively. The EQE(max) of TPA-BT-PBI and TPA-BT-IM based doped devices increased significantly up to 7.78% and 9.41%, respectively. The experimental results demonstrate that the D-A fragment determines its optical properties and incorporating the D ' group is important to improve charge transfer balance and realize high brightness.

Automated summary

In order to improve the efficiency of organic light-emitting diodes, constructing donor-acceptor molecules with hot exciton characteristics has proven to be an effective strategy. In this study, two novel materials with hot exciton features were designed and synthesized for red organic light-emitting diodes. The efficiency was significantly improved by doping these materials in different ways.