IQDotPV · All-Inorganic Quantum Dot Films for Photovoltaic Applications

Great progress has been achieved over the last 20 years in the colloidal synthesis of semiconductor, metallic, and magnetic nanocrystals (NCs). The state-of-the-art synthetic approaches allow obtaining inorganic nanostructures with high degree of crystallinity and precisely engineered compositions, sizes, and morphologies, while solubility in nonpolar solvents provides remarkable processability of colloidal nanomaterials. In the present time, research efforts are largely focused on the implementation of colloidal nanocrystals in a broad spectrum of electronic and optoelectronic devices. Highly promising is the use of colloidal semiconductor nanocrystals (also known as colloidal quantum dots, QDs) in solar cells with the theoretical potential to overcome the Shockley–Queisser limit of 31-41% power efficiency for single bandgap solar cells. Recently, Sargent et.al. have shown that electronic properties of colloidal NC films currently limit performance of nanocrystal-based solar cells. Efficiency of the carriers’ transport through NCs in the NC solid strongly depends on NC environment. However, NCs prepared by traditional colloidal techniques are capped with long-chain hydrocarbon ligands (“organic capping”) introducing insulating layers around each NC. Significantly improved charge transport has been achieved by using shorter organic linking molecules or by partial removal of ligands by hydrazine treatment. Yet small and volatile organic molecules cause instabilities in solid state devices. Recently, an important breakthrough has been made through the use of small and chemically simple inorganic ligands such as discovery of metal-chalcogenide complexes and metal-free inorganic ligands.The goal of this project is to design inorganic surrounding for colloidal nanocrystals that will lead to semiconductor NC solids with predictable optoelectronic characteristics and eventually to novel absorber layers for all-inorganic, stable and efficient solar cells.