Optical response and excitonic effects in graphene nanoribbons derived from biphenylene

• Reveal the quasiparticle band gaps of biphenylene-based ribbon.
• The excitonic effects dominate the optical spectra in these ribbons.
• The strongest excitonic absorption peaks locate at visible range.
• The first bright bound excitons are more stable than those in regular ones.

The electronic and excitonic optical absorption properties of newly fabricated nanoribbons from biphenylene are investigated via the GW   and Bethe–Salpeter equation calculations. The results reveal that the quasiparticle band gaps of R4,6,8n (n=1, 2as, 2s−2) are 25%, 15% and 13% larger than the corresponding regular AGNRs which have almost the same widths. Importantly, all the strongest excitonic absorption peaks of these ribbons locate at visible range of wavelength while their regular counterparts are in infrared range. Furthermore, the first bright bound excitons in these new ribbons are more stable than those in regular ones showing the stronger electron–hole interaction in the biphenylene-based ribbons.