An enhanced fluorescent ZIF-8 film by capturing guest molecules for light-emitting applications

Abstract

Metal organic frameworks (MOFs) constructed from metal ions/clusters and organic linkers have led to new porous luminescent materials and, thus, have attracted much attention. But their photoluminescence quantum yields (PLQYs) are not high and the photoluminescence mechanism is still unclear. In order to solve this problem, in this work, zeolitic imidazolate framework-8 (ZIF-8, a kind of MOF) composite films containing small molecules of acetic acid were successfully prepared on a glass substrate via a sol–gel method, and they exhibited a high PLQY of 54.42%. Compared with pure ZIF-8 film, the obtained ZIF-8 composite film presented a significant enhancement in blue light emission. Moreover, the PLQY of the ZIF-8 composite film can be controlled to a certain extent via adjusting the molar ratio of the ligands to the zinc source. Among them, ZIF-8 film prepared at a molar ratio of 2.5 : 1 showed higher transmittance, and the fluorescence quantum efficiency reached 54.42%, which may be attributed to electron transfer between acetic acid as an electron-donor and the ZIF-8 structure caused by their relatively strong hydrogen bonding interactions. This work may provide new insights into the enhanced fluorescence of MOF materials for light-emitting applications.