Ambient, tunable room temperature phosphorescence from a simple phthalimide phosphor in amorphous polymeric matrix and in crystalline state

Harvesting triplet excitons via room temperature phosphorescence (RTP) from purely organic chromophores has been a formidable challenge, which has a potential applications in displays, lighting, and bio-imaging. Herein, a simple phthalimide phosphor derivative is reported, which exhibits visible cyan emissive phosphorescence in solution-processable thin films and orange-red emitting phosphorescence in the crystalline state. Presence of carbonyl group and the bromine atom in the molecular design effectively increases the inter-system crossing (ISC) and spin-orbit coupling efficiency (SOC) between singlet and triplet states, which play a crucial role in achieving efficient phosphorescence under ambient conditions.