Methods, adapted from photographic microcrystal growth technology, are used to assemble organized ternary organo-inorganic, nanoscale heterostructures. The resulting ensemble consists of free-standing, oriented AgBr microcrystals, upon the <111> surfaces of which is self-assembled a monolayer of spectrally sensitizing dye, and upon the corners of the hexagonally shaped AgBr substrates are epitaxially grown nanoscale p-type CuSCN nodules, EPR spectroscopy and photophysical measurements are employed to show that the ensembles are capable of separating photogenerated geminate pairs. One of the remarkable features of this approach is that it utilizes the ultrafast kinetics of aqueous precipitation and, thus, allows the assembly of heterostructures at rates of 10(10)/s(.)L, or greater.