The rich and diverse aspect of nanomaterials for energy conversion and storage has been the research topic for many researchers. Photovoltaic solar cells for the direct conversion of sunlight to electricity can be grouped under three generations. One approach targets solar cells that can deliver a solar-to-electrical conversion efficiency well beyond the single-junction Schokley-Queisser limit of 32% using multi-layers of a graded series of light absorbers. One exciting possibility is a multiple exciton generation (MEG) solar cell. MEG refers to the process where a high energy photon can produce more than one electron-hole pair per absorbed photon. In another key development, the design of inverted polymer solar cells with high solar-conversion efficiency has been reported. Carbon-dots are superior in terms of high aqueous solubility, robust chemical inertness, easy functionalization, high resistance to photobleaching, low toxicity and good biocompatibility.