Synthesis and characterization of Al- and In-doped CdSe nanocrystals

Al- and In-doped CdSe nanocrystals were synthesized using a three-part core-shell synthesis. CdSe core nanocrystals were first prepared, then allowed to react with dopant precursors in the presence of weakly binding ligands, and finally overcoated with an additional shell of CdSe. The addition of Al dopants quickened shell overgrowth and led to more monodisperse nanocrystals while the addition of In dopants produced more polydisperse particles, as seen by absorption spectroscopy. Elemental analysis combined with chemical etching revealed the dopants were inside the particles and solid state ²⁷Al nuclear magnetic resonance (NMR) spectra indicated that the Al impurities were well dispersed. When the Al-doped nanocrystals were processed into thin-film transistors, enhanced n-type transport was observed with a rise in the Fermi level compared to undoped particles.