Cyano-Substituted Distyrylbenzene Derivative for Laser Media: High Solid-State Luminescence and Processabilities by Tert-Butyl Appending Design

Abstract

To create effective organic laser media, it is essential to design molecules with high photoluminescence (PL) quantum efficiency (Φ_PL), solubility-processability for facile crystal resonator formation, and structural tunability. Cyano-β-substituted distyrylbenzene (CDSB) is recognized as a potential solid-luminogen but is limited by its quantum efficiency and solubility toward crystal resonator processability. Herein the rational design for high solid-state luminescence and processability is demonstrated through designing tertiary-butyl (tBu)-appended approach. In contrast, tBu-appended CDSB, namely tBuC, has good solubility for crystal growth processability and controllability, allowing for the formation of high Φ_PL polymorphs. tBuC offers selective growth for (I) green-emissive platelet crystals or (II) blue-emissive needle crystals. The Φ_PL is 0.72 for I and 0.91 for II. The Φ_PL value for II is among the highest in the CDSB series, attributed to the segregated luminescent species based on bulky tBu. Lasing is observed for II due to the above characteristics. The addition of tBu offers a new strategy for crystal engineering toward the realization of laser media although it is a chemically simple approach.