Self-assembly of monolayers of semiconductor nanocrystallites

Described is the self-assembly of a monolayer of TiO2 nanocrystallites on a gold substrate by two related methods. In the first of these methods, a crystalline monolayer of the functionalized thiol HS-(CH2)(10)-COOH is self-assembled at an annealed gold substrate by adsorption from ethanolic solution. The modified gold substrate is then immersed in an ethanolic TiO2 colloid. TiO2 nanocrystallites are adsorbed at the terminal -COOH group of the molecules constituting the monolayer. In the second of these methods, an ethanolic colloid of TiO2 nanocrystallites is prepared in the presence of the functionalized thiol HS(CH2)(10)-COOH. The modified nanocrystallites are adsorbed at the surface of an annealed gold substrate. For each method, there is some evidence for short-range ordering of the nanocrystallites constituting the close-packed monolayer adsorbed at the gold substrate. Some potential applications of these methods are considered.