A plethora of nanomaterials have been synthesized and time is ripe to assemble such nanomaterials to solve the current critical energy and environmental issues facing humanity.The key is to understand the interplay between the material components.In this talk, I will present some of our recent results in interfacing and assembling different nanostructures down to molecular levels.First, I will describe the assembly of photoanodes for sensitized solar cells by a linker seeding chemical bath deposition (LS-CBD) method and by using a newly synthesized metal-free organic sensitizer family.The former has allowed full and even coverage of CdSe on the TiO2 surface in large area, yielding much enhanced power conversion efficiency of quantum dot sensitized solar cells.The latter used dithiafulvenyl unit as an excellent electron donor for constructing D-π-A type metal-free organic sensitizers of dye-sensitized solar cells (DSCs).Devices based on these dyes exhibit a dramatically improved performance with the increasing π-bridge length, culminating in η =8.29% under standard global AM 1.5 illumination, which compares favorably with that of a Ru-N719-based device (η=8.76%) evaluated under similar conditions.We attribute the enhanced Jsc to the increased photoresponsivity / charge injection and the improved Voc to the retarded electron recombination as the π-bridge length increases.Then I will introduce the assembly of graphene oxides under different conditions and the applications of the assembled graphene oxide based nanomaterials for high-performance energy storage.