Peri-Acenoacene for Solution Processed Distributed Feedback Laser: The Effect of 1,2-Oxaborine Doping

Zigzag edged nanographenes such as peri-acenoacenes are promising materials for organic lasers, but the effects of heteroatom doping on the electronic properties and gain medium performance remain unclear. Herein, the facile synthesis of a new 1,2-oxaborine (BO) doped peri-tetracenotetracene derivative, the bis(1,2-oxaborine)peri-tetracenotetracene (BOTT-Mes), is reported. X-ray crystallographic analysis confirms the BO-doped planar structure and the nonexistence of intermolecular π–π stacking in solid state. Compared with the all-carbon peri-tetracenotetracene derivative (TT-Ar), the BO-doped BOTT-Mes exhibits more disrupted π-conjugation at the BO sites, a lower-lying highest occupied molecular orbital, and a larger energy gap. Due to its rigid skeleton and nonaggregative feature, it displays well-resolved absorption and emission spectra with a small Stokes shift (8 nm) and high photoluminescence quantum yield (80%) when it is dispersed in a polystyrene (PS) thin film. Notably, 1,2-oxaborine doping improves the film amplified spontaneous emission (ASE) performance, with a lower ASE threshold (Eth-ASE = 66 µJ cm–2) as compared to the TT-Ar doped PS film (Eth-ASE = 100 µJ cm–2). Furthermore, a low threshold (22 µJ cm–2) solution-processed distributed feedback laser is fabricated, indicating the feasibility of using BOTT-Mes as gain medium for practical laser applications. J.W. acknowledges financial support from A*STAR Advanced Manufacturing and Engineering grant (A20E5c0089) and National Research Foundation Investigatorship Award (NRF-NRFI05-2019-0005). The group at the University of Alicante acknowledges financial support from the “Ministerio de Ciencia e Innovación” of Spain, European Regional Development Fund and European Social Funds (PID2019-106114GB-I00 and BES-2016-077681) and from the Conselleria de Innovación, Universidades y Sociedad Digital de la Comunidad Valenciana (Grant No. AICO/2021/093).