Symmetry-Directed Engineering of Quantum Defects: Toward Monodispersed Organic Color Centers in Carbon Nanotubes

Achieving spectrally uniform single-photon emission is crucial for scalable quantum photonics, yet conventional approaches often yield broad and unpredictable emission. Here, we report on the selective creation of organic color centers (OCCs) on high-symmetry zigzag (10,0) single-walled carbon nanotubes via a [2 + 2] cycloaddition reaction with 4-cyclopentene-1,3-dione. Density functional theory predicts two possible OCC binding configurations separated by >200 meV, favoring the selective formation of a single OCC geometry. Through chirality sorting, hyperspectral photoluminescence imaging, and multi-step spectral screening, we isolate functionalized (10,0) nanotubes and observe a substantially narrower distribution of OCC emission wavelengths than similarly functionalized chiral nanotubes. Time-resolved photoluminescence and photon correlation measurements further confirm single-photon emission at room temperature. These results demonstrate divalent OCCs on symmetric nanotubes as promising quantum emitters, offering a route toward scalable atomically defined light sources for integrated photonics.