Enhancing performance of quantum-dot light-emitting diodes based on poly(indenofluorene-co-triphenylamine) copolymer as hole-transporting layer

The hole-transporting materials (HTMs) with high hole mobility are essential for optimizing carrier balance and enhancing the performance of quantum-dot light-emitting diodes (QLEDs). In this report, the poly(indenofluorene-co-triphenylamine) copolymer (PIF-TPA) was used to replace the poly(fluorene-co-triphenylamine) copolymer (PF-TPA) as the hole-transporting layer (HTL) of red QLEDs. The maximum luminescence efficiency of red QLED increased from 9.75 cd/A for PF-TPA to 11.68 cd/A for PIF-TPA. Interestingly, the device based on PIF-TPA as HTL demonstrated lower turn-on voltage and longer device lifetime than PF-TPA. The improvement device performance should be attributed to the indenofluorene group with a rigid coplanar and an extensive π -conjugated structure to enhance the hole mobility, resulting in more balanced hole and electron injection. Our results indicate that the copolymer of indenofluorene and triphenylamine is a very promising HTM for enhancing performance of QLEDs.