Air-stable high-PLQY cesium lead halide perovskites for laser-patterned displays

Metal halide perovskites (MHPs) have emerged as attractive building blocks for advanced photoluminescence display applications. But the practical deployment of MHP displays is hindered by the relatively low air stability, which can cause difficulty in high-precision film patterning under ambient conditions while achieving high photoluminescence quantum yields (PLQYs). Here we incorporate a polymer additive of poly(2-ethyl-2-oxazoline) (PEtOx) in the solution processing of quasi-2D phenylbutylamine bromide/cesium lead halide (PBABr/CsPbBr_0.6I_2.4) perovskite films, which not only results in a high PLQY of 91%, but more importantly improves the ambient stability via Lewis base-acid interaction of oxygen functional groups of the polymer and Pb of the perovskite. Using time-resolved optical spectroscopy and femtosecond transient absorption spectroscopy, we find that in the PEtOx-stabilized quasi-2D perovskite film, the trap-assisted nonradiative recombination rate is reduced while the radiative recombination is significantly promoted, underpinning the PLQY improvements. Via mask-less laser direct-write patterning onto this air-stable high-PLQY perovskite film, we have achieved complex-patterned displays on both rigid and flexible substrates, with anti-counterfeiting encryption code as a proof-of-concept demonstration. This work opens new opportunities for engineering perovskites to multifunctional display applications.