Assembly of ZnO particles by micromoulding in top-gathering pillar array

Pyramidal shaped assemblies of ZnO particles were fabricated by micromoulding in top-gathering pillar arrays. The top-gathering pillar arrays were fabricated from organic–inorganic hybrid materials derived from the sol–gel method by UV lithography. In the top-gathering pillar arrays, the four pillars with 3 μm diameter and 12 μm height were gathered at the top and they were arranged periodically. Drops containing suspended ZnO particles were poured into the top-gathering pillar arrays. The particles were moulded in the top-gathering pillar units, although they were remained partially on the substrate. The assembly of ZnO particles emitted strongly photoluminescence, and the photoluminescence spectrum had two peaks, which were assigned to band-edge and oxygen vacancy. It was found that the micromoulding technique using top-gathering arrays was useful to produce new periodic patterns for luminescence devices.