ofCdSeNanocrystallites into Three-Dimensional QuantumDotSuperlattices

orliquid interface asathin, ordered superlattice ofdots. Inbothcases, thesize and spacing ofthedots arecontrolled witha precision that islimited byatomic roughness. Assembly ataninterface hastheaddedbenefit thatboththesuperlattice and theindividual dotshavetheir crystallographic axesoriented withrespect tothe interface, presenting anopportunity tocontrol andstudy optical anisotropy inthe individual crystallites andintheordered arrays. Nanocrystallites ofCdSeareideal buildingblocks fortheformation ofQD superlattices. Synthetic methods produce macroscopic quantities ofsingle-domain wurtzite crystallites with lowdefect densities, auniformshape (slightly prolate along their c axis withanaspect ratio of-1.1to1.2), andsizes that aretunable from-15to100 A indiameter (standard deviation <4%) (9). Efficient electronic passivation witha close-packed monolayer ofcoordinating ligand(trioctylphosphine