Photoluminescence Enhancement by Light Harvesting of Metal–Organic Frameworks Surrounding Semiconductor Quantum Dots

Metal–organic framework (MOF) based light harvesting has been attracting considerable attention as an artificial antenna for photochemical and photophysical applications. Herein, we report the photoluminescence enhancement of semiconductor quantum dots (QDs) via efficient energy transfer from a light-harvesting framework (IRMOF-3) surrounding each QD as a surface modifier. IRMOF-3 crystals were directly grown on the surface of QDs without any intermediate layer such as polymers. The observed photoluminescence enhancement owing to the light harvesting of IRMOF-3 was confirmed by both steady-state excitation spectra measurement and fluorescence lifetime measurement. The phenomenon was observed at the wavelength region where IRMOF-3 had high absorbance. On the basis of the Förster distance (R₀) between the donor and acceptor, the volumetric factor of IRMOF-3 from which the excitation energy was transferred to QDs was estimated. We experimentally demonstrated that the energy transfer efficiency was 11 times higher when QDs were fully coated by IRMOF-3 than when QDs were attached to the surface of IRMOF-3. The PL intensity from QDs was almost doubled under optimal conditions, which indicates the advantage of using light-harvesting MOFs as a surface modifier for luminescent QDs.