Double bubble secondary building units used as a structural motif for enhanced electron–hole separation in solids

A structural motif designed for enhancing electron–hole separation in semiconducting composite materials, the so-called double bubble, is introduced. The addition of silicon carbide in the construction of heterogeneous double bubble systems, along with zinc oxide and gallium nitride, yields electronic structures that are favourable for electron–hole separation. The standard formation enthalpies of such systems are comparable with those of fullerenes, suggesting that these systems would be achievable and of direct benefit to photovoltaic and electrochemical applications such as water splitting; with the (SiC)12@(ZnO)48 proving to be the most promising building block for future functional composite materials. & 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).