Self-assembly,driven by non-covalent interactions is the fundamental mechanism behind the formation of cellular machineries that perform essential functions of life.It has been found that interaction anisotropy dictates the structural complexity and functional specificity of nat urally occurring cellular machineries.This finding stimulates research efforts based on anisotropy to design and control the self-assembly of nanoparticles into well-defined two-dimensional(2D)and 3D complex structures,which may provide a low-cost,programmable paradigm to synthesize functional solid-state materials that are not easily accessible via conventional methods.For example,these materials can exhibit properties inherited from their individual nanoparticle constituents as well as collective properties induced from the coupling effects between their constituents.In the current literature,the discovered collective properties of nanoparticle superlattices include spin-dependent electron transport,vibrational coherence,enhanced conductivity,tandem catalysis,reversible metal-to-insulator transitions,enhanced ferro-and ferrimagnetism,tunable magneto-transport,and efficient charge transport.To overcome this difficulty,here we report a new synthesis for making needle-like CdSe/CdS supercrystals,which is based on the preparation of CdSe/CdS nanorods exhibiting a static structure with hydrophobic anisotropy through surface functionalization with 1,12 dodec anediamine.Beca use 1,12-dodecanediamine ligands are primarily functionalized onto the side faces of CdSe/CdS nanorods,their bottom and top faces exhibit more hydrophobicity than their side fac es due to the hydrophilicity of am ine groups.Therefore,the hydrophobic anisotropy of the resultant nanorods leads to the formation of needle-like superparticles through a process of self-assembly of these nanorods.Significantly,the surface treatment of 1,12-dodecanediamine requires only 10 min,and the quality of the res ulting needle-like superparticles is comparable to that of those made using octylamine treatment for 6 to 7 days.In addition,because the 1,12-dodecanediamine functionalized nanorods exhibit a static hydrophobicity-anisotropic structure,the synthesis here can yield needle-like superparticles with di ameters of(2.00±0.43)×100 nm,which is about five times narrower than those needle-like superparticles(1.1±0.3)×1000 nm made using the octylamine treatment.These narrower superparticles are important in their applications as energy-down conversion LEDs because a narrower size can minimize the light loss caused by Rayleigh scattering,which is important for their use as energy down-conversion phosphors in manufacturing polarized light-emitting diodes(LEDs,Fig.1).