Fused Triangulene Dimers: Facile Synthesis by Intramolecular Radical‐Radical Coupling and Application for Near‐Infrared Lasers
Tong Shen, Diego Dijkstra, Álex Farrando‐Pérez, Pedro G. Boj, José M. Villalvilla, José A. Quintana, Ya Zou, Xudong Hou, Haipeng Wei, Zhentao Li, Zhe Sun, María A. Díaz‐García, Jishan Wu
Abstract
Large graphene-like molecules with four zigzag edges are ideal gain medium materials for organic near-infrared (NIR) lasers. However, synthesizing them becomes increasingly challenging as the molecular size increases. In this study, we introduce a new intramolecular radical-radical coupling approach and successfully synthesize two fused triangulene dimers (1 a/1 b) efficiently. X-ray crystallographic analysis of 1 a indicates that there is no intermolecular π-π stacking in the solid state. When the more soluble derivative 1 b is dispersed in polystyrene thin films, amplified spontaneous emission in the NIR region is observed. Using 1 b as the active gain material, we fabricate solution-processed distributed feedback lasers that exhibit a narrow emission linewidth at around 790 nm. The laser devices also exhibit low thresholds with high photostability. Our study provides a new synthetic strategy for extended nanographenes, which have diverse applications in electronics and photonics.