Tuning the Electronic and Optical Properties of Graphene Quantum Dots via Cu Dimer Doping: A DFT Study

Graphene quantum dots (GQDs) are emerging as promising nanomaterials for next-generation energy devices due to their tunable electronic and optical properties. However, optimizing their band gap and charge transport remains a challenge. In this study, we employ density functional theory (DFT) to investigate the influence of Cu dimer doping on the structural, electronic, and optical characteristics of GQDs. Our results show that Cu₂ doping reduces the band gap significantly from 4.130 eV in pristine GQDs to as low as 1.059 eV enabling enhanced electrical conductivity and extended optical absorption into the infrared region. The Cu₂-2 configuration demonstrates the most favorable electronic delocalization and dipole behavior, highlighting its suitability for optoelectronic and energy-related applications. These modifications improve the material’s potential for use in solar energy harvesting, infrared photodetectors, and energy storage devices. This study demonstrates a viable pathway to engineer low-band-gap, highly conductive GQDs for wearable electronics.