Efficient Deep-Blue (465 nm) Perovskite Quantum Dot-Based Light-Emitting Diodes via Triphenylamine Derivative Tailored Hole Transport Engineering

Metal halide perovskite quantum dot-based light-emitting diodes (QLEDs) have garnered considerable attention for realizing wide color gamut displays. Despite the breakthrough achieved in sky-blue perovskite QLEDs, it is still challenging to realize efficient Rec. 2020-blue perovskite QLEDs. Herein, a triphenylamine derivative-tailored hole transport layer (HTL) strategy is proposed for improving hole injection in deep-blue perovskite QLEDs. The hole mobility of the tailored HTL (T-HTL) is enhanced by ≈3.5 times compared to the pristine HTL (P-HTL) by mixing the 4,4′-cyclohexylidenebis [N, N-bis(p-tolyl) aniline] (TAPC) into poly [bis(4-phenyl) (4-butylphenyl) amine] (Poly-TPD), and the highest occupied molecular orbital (HOMO) level of T-HTL is shifted down by 0.11 eV compared to P-HTL, facilitating hole injection into the emitting layer. The resulting deep-blue perovskite QLEDs exhibit an external quantum efficiency of 11.0% at 465 nm, meeting the Rec. 2020 standard and representing the state-of-the-art deep-blue perovskite QLEDs. Theoretical calculations and experimental results demonstrate that the enhanced hole transport capacity of the T-HTL is attributed to the intermolecular π–π stacking between TAPC and Poly-TPD. Other triphenylamine derivatives can also tailor the hole transport capacity and improve device performance, which demonstrates the universality of the proposed strategy.