Effect of Benzene Derivatives as Guest Molecules on Semiconductor Properties of MOF-199

Abstract

A metal organic framework, MOF-199, has been synthesized under solvothermal conditions. Powder X-ray diffraction (PXRD) pattern, Fourier-transform infrared spectra (FT-IR) and scanning electron microscopic images (SEM) confirmed the formation of the expected MOF-199 structure. The semiconductor properties of MOF-199 were then fine-tuned by introducing three benzene derivatives as guest molecules (aniline, m-aminobenzoic acid and p-benzoquinone). Modified MOF-199 samples were characterized using PXRD and FT-IR. Mott-Schottky analysis and solid-state UV-visible spectroscopy were used to investigate the semiconductor properties of these materials. Once MOF was modified with benzene derivatives, slight changes in d spacing values of PXRD patterns and appearance of new peaks in FT-IR spectra were observed. The Mott-Schottky analysis of modified MOF-199 demonstrated an enhancement in the carrier concentration up to 83 % and a negative potential shift of the flat band potential compared to pure MOF-199, indicating a higher degree of band bending. According to the solid-state UV-visible spectra, doping with organic molecules reduced the bandgap in modified MOF-199. Thus, this study evidently showcases the potential of fine-tuning the semiconductor properties of a MOF according to the requirement that allows a single MOF to be utilized in a variety of applications with a simple modification.