Gradient Dopant Zinc Oxide Nanoparticles for Electron Transport

The patent applies local quality by creating a concentration gradient of dopant metals within the zinc oxide nanoparticles. The dopant concentration varies from the inner portion to the outer portion of the nanoparticles, with higher concentration in one region and lower in another. This spatial variation in composition allows different regions of the nanoparticle to exhibit different electrical properties, enabling simultaneous optimization of electron transport (in regions with appropriate dopant concentrations) and contact resistance (in regions with optimized dopant gradients), thus resolving the technical contradiction.

The patent employs parameter changes by systematically varying the dopant metal concentration as a continuous gradient rather than using uniform concentrations. By controlling the dopant concentration to vary spatially within the nanoparticle structure (from inner to outer portions), the patent transforms a discrete manufacturing parameter (uniform dopant amount) into a continuous gradient parameter, enabling fine-tuned control of electrical properties while maintaining manufacturing feasibility through controlled gradient formation.

The patent introduces dopant metals (such as Mn, Ni, Sn, Al, Y, Ga, or Zr) as intermediary elements within the zinc oxide nanoparticle structure. These dopant metals act as mediators that modify the electronic and optical properties of the cadmium-free quantum dot system. The dopants facilitate charge balance and enhance luminous properties by creating appropriate energy levels and improving electron-hole recombination efficiency, thereby enabling cadmium-free quantum dots to achieve desired performance without compromising environmental safety.