Engineering <i>γ</i>-graphyne quantum dots for photoactive applications and <i>in vitro</i> bioimaging

Abstract Graphyne is the only known 2D material combining sp and sp 2 hybridization, with γ -graphyne identified as its most stable allotrope. However, its quantum dots ( γ -GYQDs) remain largely unexplored. This study investigates diamond-shaped and triangular γ -GYQDs using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) simulations, focusing on stability, optoelectronic properties, and quantum confinement effects. We find that acetylenic bonds play a crucial role in stabilizing larger diamond-shaped γ -GYQDs. Functionalization has minimal impact on energy gaps, preserving key optical properties. Notably, the electronic structure aligns well for photoactive applications, with the HOMO level below the electrolyte’s I − /I <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> redox potential and the LUMO above TiO 2 ’s conduction band. Additionally, size-dependent red-shifts in absorption and emission spectra suggest strong potential for photovoltaics and biomedical applications. Furthermore, γ -GYQDs exhibit distinct quantum confinement effects due to their acetylenic linkages, highlighting their promising optoelectronic behavior for next-generation nanotechnology applications.