Theoretical insights into the room temperature phosphorescence properties in star-shaped carbazole-based molecules

Abstract

Room temperature phosphorescence (RTP) using pure organic compounds is highly desirable for a wide variety of applications in the optical electronics and biological fields. Herein, we studied the RTP properties of a few star-shaped pure organic molecules based on carbazole and chalcogen atoms using quantum chemical methods. The calculated intersystem crossing (ISC) rate constant is found to be ∼10^8–10 s⁻¹ for these molecules. The ISC and efficiency of RTP are increased by incorporating a heavy halogen atom, which is facilitated by strong SOC. In contrast to the traditional organometallic phosphors used in OLEDs, this study illustrates the rational molecular design of metal-free organic room-temperature phosphorescent emitters containing chalcogen and halogen atoms.