Low voltage operating organic light emitting transistors with efficient charge blocking layer

Charge injection/blocking layers play important roles in the performances of organic electronic devices. Their incorporation into organic light emitting transistors has been limitted, due to generally high operating voltages (above 60 V) of these devices. In this work, two hole blocking molecules are integrated into tris-(8-hydroxyquinoline) aluminum (Alq(3)) based light emitting transistors under operating voltage as low as 5 V. The effects of hole blocking and electron injection are decoupled through the differences in the energy levels. Significantly improved optical performance is achieved with the molecule of suitable energy level for electron injection. Surprisingly, a decreased performance is observed in the case of another hole blocking molecule evidencing that charge injection overweighs charge blocking in this device architecture.

Automated summary

Charge injection/blocking layers are important in organic electronic devices, but their use in organic light emitting transistors has been limited by high operating voltages. In this study, two hole blocking molecules were integrated into light emitting transistors, resulting in improved optical performance at lower operating voltages. However, the choice of molecule for charge injection can also impact device performance.