In the present study, we successfully synthesized N-doped carbon quantum dots (N-CQDs) using a top-down approach, i.e., hydroxyl radical opening of fullerene with hydrogen peroxide, in basic ambient using ammonia for two different reaction times. The ensuing characterization via dynamic light scattering, SEM, and IR spectroscopy revealed a size control that was dependent on the reaction time, as well as a more pronounced -NH₂ functionalization. The N-CQDs were probed for metal ion detection in aqueous solutions and during bioimaging and displayed a Cr³⁺ and Cu²⁺ selectivity shift at a higher degree of -NH₂ functionalization, as well as HEK-293 cell nuclei marking.

We have investigated the structural, optical, and electrical properties of alumina-doped zinc oxide (AZO) thin films, grown by pulsed laser deposition. The optical transmittance of the films is over 80% in the visible region, and the absorption edge shifts from about 380 nm of the undoped sample to 320 nm of the AZO film. The calculated optical band gap $\left(E_g\right)$ of $2\text{wt}\%$ AZO films shows a widening up to 3.82 eV with respect to the undoped film (3.28 eV). Higher doping concentration $\left(6\text{wt}\%\right)$ leads to films with larger $E_g$ (4.1 eV), but also epitaxial properties are affected. A further widening of the gap occurs when the AZO films are deposited by lowering the substrate temperature $\left(T_s\right)$ from 450 to $250°\text{C}$ . These blueshifts are respectively attributed to the increase in carrier concentration, induced by Al-donor doping, and also a lower degree of crystalline order. AZO films with doping concentration of $2\text{wt}\%$ show resistivity values of about ${10}^{-3}\Omega \text{cm}$ and the local $I\text{-}V$ curves, measured by scanning tunneling spectroscopy, show higher tunneling current than ZnO film. The Al-doping route proved to be effective in tailoring the optical and electrical properties without essentially affecting the crystalline structure of the films.