Gravity-assisted convective assembly of centimeter-sized uniform two-dimensional colloidal crystals.

We have developed an inexpensive, robust, and easily controlled method, a gravity-assisted convective self-assembly method, to fabricate centimeter-sized uniform two-dimensional colloidal crystals. In this method, centimeter-sized two-dimensional colloidal crystals can be formed when the suspension concentration is in the range of 0.32-2.5 wt %. Once the ordering process starts, the formation of two-dimensional colloidal crystals is not affected when the environmental temperature gradually increases from 3 to 10 °C. Experimental results indicate that, in this method, gravity plays an important role in the colloidal crystal formation. The colloidal particles are transported to the edge of the suspension-glass interface, and the extra particles can be eventually moved to the edge of the slide by gravity.