Engineering of Hole Transporting Interface by Incorporating the Atomic-Precision Ag6 Nanoclusters for High-Efficiency Blue Perovskite Light-Emitting Diodes

The property of the underlying hole transport layer (HTL) plays a crucial role in determining the optoelectronic performance of perovskite light-emitting devices (PeLEDs), as their governing abilities in carrier injection and charge transport. However, endowing the current HTL system with a deep highest occupied molecular (HOMO) level concurrent with high hole mobility is still a big challenge, in particular being an open constraint toward high-efficiency blue (range of 460–495 nm) PeLEDs. In this regard, employing the traditional HTL material of poly(9-vinylcarbazole) (PVK) as a model, we perform efficient incorporation of the atomic-precision metal nanoclusters (NCs), [Ag 6 PL 6 , PL = (S)-4-Phenylthiazolidine-2-thione], to achieve significant tailoring in both of HOMO energy level (from − 5.8 eV to -5.94 eV) and hole mobility from (2.5×10 − 5 to 2.34×10 − 4 cm 2 V − 1 s − 1 ), thus realizing the flat-band injection of holes between HTL and emitting layer and a strengthened ability in hole transport. As a result, the as-modified PeLEDs exhibit an external quantum efficiency (EQE) of 12.02% at 488 nm, which is around 1.3 times higher than that of the control device, i.e., 9.48%. The presented study exemplifies the success of metal NCs involved in HTL engineering by deepening the concept of the metallic molecule, and offers a simple while an effective additive strategy to settle the blue PeLEDs HTL dilemma, which paves the way for the fabrication of highly efficient blue PeLEDs.