Structure direction of II-VI semiconductor quantum dot binary nanoparticle superlattices by tuning radius ratio.

We report a nanoparticle radius ratio dependent study of the formation of binary nanoparticle superlattices (BNSLs) of CdTe and CdSe quantum dots. While keeping all other parameters identical in the system, the effective nanoparticle radius ratio, gamma(eff), was tuned to allow the formation of five different BNSL structures, AlB(2), cub-NaZn(13), ico-NaZn(13), CaCu(5), and MgZn(2). For each structure, gamma(eff) is located close to a local maximum of its space-filling factor, based on a model for space filling principles. We demonstrate the ability to select specific BNSLs based solely on gamma(eff), highlighting the role of entropic forces as a driver for self-assembly.