ABSTRACT
Fabrication of future generation solar cells using semiconductor nanocrystal (NC) superlattice structures has been intensively focused in the recent years due to the salient properties of NC assemblies. Although the preparation of semiconductor nanocrystals in aqueous or organic medium relies on the different kinds of organic functional molecules (i.e. ligands), the performance is mostly affected with respect to their chemical reactivity in films. Some of the ligand molecules have a short chain while some of them have a long chain, which hardly affects the functionality of the NCs. Since this difference makes great impact on the device efficiency, it is necessary to exchange the long-chain (or) insulating ligand molecules by short-chain ligands and this can be achieved either in solid-state or in colloidal medium. Through this approach, the NCs are electronically coupled together and carrier transport of the NC film is enhanced. Along with the ligands, solvents also play an important role in the ligand exchange strategy. In this view, this chapter discusses the chemical aspects and different approaches of ligand exchange process in the NC superlattice structures for the fabrication of highly efficient solar cell devices. This includes the role of ligand exchange in the semiconductor quantum dot solids (cadmium chalcogenides, lead chalcogenides, etc.) and all-inorganic halide perovskite nanocrystal assemblies (CsPbX 3 where X = Cl, Br, I) on the performance of solar cells such as quantum-dot sensitized solar cells (QDSSCs), hybrid solar cells and perovskite nanocrystal solar cells.
