Computational Details All molecular structures were optimized using density functional theory (DFT) using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional as implemented in Gaussian16. The Pople basis set 6-311G(d,p) of triple-ζ quality augmented with polarization functions was employed. All current density calculations have been carried out using DFT as implemented in Atomic Simulation Environment (ASE) and GPAW. The PBE exchange-correlation functional and a double-ζ plus polarization basis set were used for all atoms except hydrogens where a single-ζ basis set was used. We set the Fermi energy to the mid-point between the energy of the HOMO and LUMO. Therefore, unless otherwise noted, all current density results are calculated at (EHOMO + ELUMO) • 0.5 = EF .