TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In the method (M1), the precipitating comprises washing the nanocrystals in the reaction mixture with a first apolar solvent; dissolving the washed nanocrystals in a second apolar solvent; and rinsing the dissolved nanocrystals in the first apolar solvent at least twice. The washing comprises washing the nanocrystals with ethanol. The dissolving comprises dissolving the washed nanocrystals in hexane or toluene. The dissolving comprises dissolving the final precipitate in the apolar solvent. The injecting comprising varying the temperature of the solution is 230-280 degrees C. The injecting comprising varying the growth temperature of the solution is 210-260 degrees C. The injecting comprises allowing the mixture, the solution, and the solvent to react for a time that allows for the incorporation of aluminum in the aluminum precursor into the crystal lattice of a zinc oxide resulting from the injecting. The injecting comprises allowing the mixture, the solution, and the solvent to react for 2-5 hours. The method (M1) further involves depositing the nanocrystals from the dissolved precipitate on a substrate, thereby resulting in at least one aluminum-zinc oxide nanoparticles film; and removing organic ligands from the surfaces of the nanoparticles in the aluminum-zinc oxide nanoparticles film. The depositing comprises depositing the nanocrystals from the dissolved precipitate on the substrate. The removing comprises performing thermal annealing on the nanoparticles in the aluminum-zinc oxide nanoparticles film. The removing comprises exchanging the organic ligands with an inorganic salt, or other organic ligands. Preferred Nanocrystals: The nanocrystals in the dispersion and film comprise aluminum-doped zinc oxide nanocrystals, where the nanocrystals are less than or equal to 50 nm in size. The nanocrystals in the film are coated with surfactants. Preferred Components: The substrate is selected from glass, silicon, quartz, indium tin oxide, fluorine-doped SnO2, or polar solvents.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The surfactants in the dispersion and film comprise fatty acids. The zinc precursor is selected from zinc stearate, zinc acetylacetonate, and zinc acetate. The aluminum precursor is selected from aluminum acetylacetonate, aluminum stearate, or aluminum oleate. The amine comprises oleylamine. The fatty acid is selected from oleic acid or stearic acid. The vicinal diol is selected from 1,2-dodecanediol, 1,2-hexadecanediol, or 1,2 octanediol. The non-coordinating solvent is selected from octadecene, benzylether, or phenylether. The apolar solvent is hexane, toluene, or chloroform. EXAMPLE - Preparation of aluminum-doped zinc oxide nanocrystal was carried as follows: a solution (A) containing zinc stearate (1 mmol), aluminum acetylacetonate (0.05-1 mmol), oleic acid (3 mmol) in octadecene (4 ml) and a mixture (B) of 1,2-hexadecanediol (10 mmol) in octadecene (11 ml) were loaded in three-neck flasks and magnetically stirred at 140 degrees C under argon for 1 hour. Ethanol was added, and the nanocrystals (NCs) were separated from the reaction mixture by centrifugation (9000 rpm for 20 minutes). After two cycles of redispersion in hexane (1 ml) and reprecipitation by ethanol, 20-30 mg of precipitate was eventually collected and dispersed in a suitable nonpolar solvent to obtain aluminum-doped zinc oxide nanocrystal.