Anomalous Effect of Intramolecular Charge Transfer on the Light Emitting Properties of BODIPY

A new way to approaching
highly emissive BODIPY dyes in both solution and solid state is achieved
by introducing intramolecular charge transfer (ICT). A hybrid excited
state that shows behaviors of both the ICT excited state and local
excited state is discovered to be beneficial in avoiding the disturbance
from the rotation vibration of the flexible phenyl substituents. Thus,
the nonradiative transition process is suppressed, and the fluorescence
efficiency goes up. By modification of the excited state, we realize
emission enhancement of crystalline BODIPY derivatives with a PLQY
from 0.08 to 0.27, and the compound expresses a good potential application
prospect in organic semiconductors.