Nonequilibrium bandgap modification in porphyrin-based metal-organic frameworks revealed by transient absorption spectroscopy.

This article focuses on the investigation of nonequilibrium bandgap modification in cobalt porphyrin-based metal-organic frameworks (Co-TCPP MOFs) using transient absorption spectroscopy. The study reveals a pronounced redshift–blueshift crossover in the optical bandgap of Co-TCPP MOFs, with a maximum shift of approximately 170 meV dependent on excitation fluence, a phenomenon absent in disordered porphyrin molecules. The findings suggest that the ordered molecular structure of Co-TCPP MOFs enhances many-body interactions and Coulomb effects, which are critical to the observed bandgap modulation. This research advances the understanding of ultrafast photophysics in MOFs and highlights the potential of bandgap engineering to improve the performance of MOF-based optoelectronic devices such as solar cells and photonic switches.