Semiconductor nanocrystals are of intense interest for photovoltaics due to large absorption cross-sections and high photostabilities. Lead chalcogenide nanocrystals are a particularly attractive system because of the facile colloidal synthesis of high quality nanocrystals with band gaps within the ideal energy range for solar energy capture (0.9-1.2 eV), and because they demonstrate carrier multiplication that can potentially increase the efficiency of suitably fabricated solar cells. Moreover, specifically designed lead-chalcogenide-based heterostructured nanocrystals are expected to exhibit properties that enhance the feasibility of realizing this promise. Growing such materials colloidally has been complicated by the instability of lead chalcogenide nanocrystals at elevated temperatures. Recently, we synthesized thermally stable PbSe/CdSe and PbS/CdS core/shell nanocrystals that represent a gateway to more complex architectures. This talk will discuss the synthesis of a new series of infrared-active nanoheterostructures based on these building blocks.