Multifunctional ammonium salts synergizing etching and passivation capability enable efficient deep-blue CsPbBr3 nanoplates

Abstract

Two-dimensional CsPbBr₃ nanoplates (NPLs) are highly promising blue emitters due to their precisely tunable emission wavelength by adjusting the thickness. However, synthesizing high-performance deep-blue emissive CsPbBr₃ NPLs with fewer monolayers remains challenging. Here, multifunctional ligands of 2,6-diaminopyridinium hydrobromide (DaPyBr) with multiple coordination sites were designed and synthesized to attenuate the thickness of blue CsPbBr₃ NPLs and suppress surface defects. DaPyBr serving both as a Lewis acid and a Lewis base possesses the dual functions of etching and passivation. It can detach the outer defect layers of CsPbBr₃ NPLs reducing the thickness to 3 monolayers and passivate inner [PbBr₆]⁴⁻ layers suppressing the surface defects. Ultimately, CsPbBr₃ NPLs treated by DaPyBr achieved a near-unity photoluminescence quantum yield at 456 nm. The target NPLs gained long-term storage stability and outstanding resistance to polar solvents. A bright deep-blue pattern display with commendable luminescence stability is achieved via aerosol printing technology.