Construct hierarchical porous covalent organic frameworks to coat CsPbBr3 nanocrystals for enhancing fluorescence performance and stability

CsPbX 3 (X = Cl, Br, I) all-inorganic perovskite nanocrystals (NCs) are a class of rapidly developing new optoelectronic materials. By virtue of their excellent luminescent properties, they have found wide application in optoelectronic devices including light-emitting diodes (LEDs), solar cells, and micro/mini-LEDs. Covalent Organic Framework (COF) coating effectively addresses the issue of insufficient stability, while it suffers from small pores and low coating efficiency. Thus, cetyltrimethylammonium bromide (CTAB) and 1, 3, 3, 5-tetramethylbenzene (TMB) were employed as swelling restrictors, and a hierarchical microporous channel structure was constructed in the COF material. CsPbBr 3 NCs was synthesized in situ through room temperature supersaturation recrystallization, forming CsPbBr 3 @TC-COF composite materials. Therefore, the COF material's pore size expanded to a layered structure ranging from 10 to 20 nm, preventing the aggregation and quenching of nanocrystals, thus enhancing the photoluminescence quantum yield (PLQY) and stability of CsPbBr 3 NCs. Specifically, the PLQY of CsPbBr 3 @TC-COF composites increased significantly from 37.71% for pristine CsPbBr 3 to 90.35%. Even after 30 days of storage at room temperature, CsPbBr 3 @TC-COF composites maintained 53.26% of their initial PL intensity, compared to 22.41% for the pristine CsPbBr 3 NCs. Additionally, they exhibited excellent stability in several polar solvents. Ultimately, through the integration of CsPbBr 3 @TC-COF composites, K 2 SiF 6 :Mn 4+ (KSF) red powder, and blue LEDs, a white LED (WLED) device was successfully fabricated. The device has an efficiency of 33.89 lm W −1 and a correlated color temperature (CCT) of 4036 K, indicating that this composite material is highly likely to be an ideal choice for next-generation lighting and display technologies.