Regulating Organic Dopant Dispersion in Polymer Matrices for Concentration‐Controlled Color‐Tunable Organic RTP Emissions

Abstract Multi‐aryl conjugated organic molecules have intrinsically poor compatibility with most polymers, although they can be dispersed into polymer matrices by solution casting film. This work proposes that this property can be used to obtain diverse dispersion states and realize unique room temperature phosphorescence (RTP). Herein, cyano‐ and amide‐containing N‐phenylcarbazoles (2Q5X, 2J5X) are doped into different polar and rigid PVA and PMMA. 2J5X/PVA emits blue and green RTP after 254 and 365 nm light excitation, respectively, whereas 2Q5X/PVA emits green RTP bearing excitation wavelength‐dependent blue‐emitting shoulder. When 2Q5X is doped into PMMA, this blue RTP becomes dominant due to the increase in molecular dispersion ratio. Combined with the investigations on RTP properties of low doping concentration polymers and crystalline and amorphous states, the blue RTP and green RTP are attributed to the emissions of the isolated molecule and the clustering molecules, respectively. This work reveals that regulating the dispersion of organic dopants in polymers can provide unique and diverse RTP properties.