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. Deep‐blue perovskite quantum dot‐based light‐emitting diode (QLED) with improved hole injection is fabricated using a triphenylamine derivative‐tailored hole transport layer. The resulting device exhibits an external quantum efficiency of 11.0% at a blue emission wavelength of 465 nm and CIE coordinates (0.13, 0.05), meeting the Rec. 2020 standards and represents the best‐performing deep‐blue perovskite QLEDs demonstrated so far.