In situ confined growth of ultrasmall perovskite quantum dots in metal–organic frameworks and their quantum confinement effect

Abstract

The metal halide perovskite quantum dots (APbX₃ PeQDs; A = Cs or CH₃NH₃; X = Cl, Br or I) have emerged as a new type of promising optoelectronic material for light-emitting and photovoltaic applications because of their excellent optical properties. However, the precise control over the size and photoluminescence (PL) emission of APbX₃ PeQDs remains a great challenge, which has been one of the main obstacles to the applications of PeQDs. Herein, we report a unique strategy for in situ confined growth of MAPbBr₃ (MA = CH₃NH₃) PeQDs by using porous metal–organic framework (MOF) UiO-66 as a matrix. By introducing Pb(Ac)₂ and MABr precursors into the pores of UiO-66 via a stepwise approach, ultrasmall MAPbBr₃ PeQDs were in situ grown in the matrix with the size tuned from 6.4 to 3.3 nm by changing the concentration of the Pb(Ac)₂ precursor. Accordingly, the PL emission wavelength of the resulting MAPbBr₃ PeQDs was blue-shifted from 521 to 486 nm with the size reduction, owing to the strong quantum confinement effect of the PeQDs. Due to the surface passivation effect endowed by the UiO-66 matrix, the ultrasmall MAPbBr₃ PeQDs also displayed a high PL quantum yield (PLQY) of 43.3% and a long PL lifetime of 100.3 ns. This study proposes a new strategy to prepare ultrasmall PeQDs and effectively control their sizes and PL emissions, which may open up new avenues for the development of high-performance luminescent PeQDs for diverse applications.