Boron and Nitrogen Co-Doping of Graphynes without Inducing Empty or Doubly Filled States in π-Conjugated Systems

Substitutional B and N doping is a powerful way to modulate the electronic properties of carbon π-conjugated materials. However, the B and N dopants in all the previously reported hybrid materials have either doubly filled or empty p _z orbitals, causing large reductions of carrier mobilities for the materials. Using density functional theory calculations, we demonstrate a different BN co-doping method for graphynes, which does not introduce any empty or doubly filled p _z states into the π-systems. Instead, electron donations between carbon and dopant atoms occur only in the σ-bond frameworks, and π-electron configurations of the hybrid graphynes are absolutely the same as those of the pristine graphynes. It thus allows opening large bandgaps for graphynes and simultaneously best reserving their prominent carrier mobilities. Following this doping method, the BCN atoms form subunits that resemble base-stabilized borylenes, which are already experimentally synthesizable. Therefore, the results pave a way to the bottom-up design and synthesis of hybrid graphyne-like materials for use as high-performance, post-silicon electronics.