Concurrent advances in synthetic methods of nanomaterials have granted us with unprecedented control over chemical, physical and mechanical properties. From the perspective of bottom-up manufacturing, to incorporate these advances into real-world applications, there is an urgent need of assembly technique, which bridges the gap between synthesis of nanometer sized building blocks and millimeter sized devices. For example, in quantum dot based optoelectronic devices, traps need to be effectively suppressed during assembly to ensure a coherent charge transport. Optically-processed assembly techniques are promising emerging techniques since they intrinsically possess temporal and spatial control by changing the dosage of light source. Besides, these systems can often work in ambient conditions and the reaction time is usually short compared to thermal treatments, which makes it a facile and versatile technique. The processes are usually initiated with the excitation of electrons of the photosensitizers. The excited electrons then trigger reactions to connect building blocks. In a direct pathway building blocks are connected by photoresponsive ligands , while in a mediated pathway connections are triggered by photoinitiated release of chemicals. This thesis will discuss two systems with different building blocks. In the first part, quantum dots are connected into two-dimensional superstructures at a fluid interface via photoinitiated release of chemical triggers. The superstructures and reaction kinetics are carefully characterized to explain the mechanisms to give insights for other systems with similar two-phase setup. As a possible application, a direct photolithography is demonstrated. In the second part, acrylated inorganic clusters are assembled into hierarchical porous structures with a porosity spanning from sub-nanometer to micrometers via photopolymerization. The formation mechanisms and corresponding conditions are identified with facile tunability of pore size distribution. The materials are incorporated into a separation column and a purification of drugs from carcinogenic impurities is successfully achieved.