Nanotechnology is the application of nanoscience to useful devices. Nanoscience can be explained as the study and manufacture of structure and devices with dimension about the size of few molecules. It is the branch of science which deals with the object with at least one dimension between one to one hundred nanometer in length, a size scale of atom molecules and super molecular structure. The nanometer sized semiconductor particles are representative of a different state of matter. This new class of material explores many properties such as size quantization, surface effect, lattice contraction, unusual fluorescence and enhanced oscillator strength, which are smaller than the diameter of their corresponding bulk excitons strongly depend on the size of the particles due to quantum confinement of the excited states. For nanoparticles, the size and surface effect are both importan. By controlling the size and surface effect, it is possible to design materials of required optical, magnetic, elastic and chemical properties. The combination of polymer with semiconducting nanoparticles allows the fabrication of thin film light emitting devices.