The invention is a synthetic method to prepare colloidal nanomaterials of V-VI-VII semiconductors that do not contain toxic elements. This is the first method for the synthesis of mixed anion nanomaterials without toxic elements at large, which permitted to obtain, among others, bismuth chalcohalide nanocrystals that are arguably considered as one of main candidates to be the next big thing for light energy conversion. Our method permits to fully explore the ternary metal-chalcogen-halogen phase diagram, providing access to a class of unexplored nanomaterials. Our synthetic method can be scaled up. Our materials show high chemical stability and superior light absorption properties. Our materials are dispersible in several media and can be used to formulate inks, pastes, and composites thus compatible with simple processing techniques (such as printing). Our materials can be processed into robust, conductive thin solid films capable of producing a stable current upon light irradiation.
High reliability of the process: our process is based on the controlled nucleation and growth of the nanocrystals in the solution phase, which are prepared by the hot-co-injection of the anion precursors in a metal complex solution. High versatility of the process: our method permits to fully explore the ternary metal-chalcogen-halogen phase diagram, providing access to a class of unexplored nanomaterials. Processability of the materials: our materials are dispersible in several media and can be used to formulate inks, pastes, and composites thus compatible with simple and cheap processing techniques (such as printing, spraying, blade coating). Rather reduced costs: our process occurs at relatively low temperatures (< 200 °C) for few minutes and utilizes common reagents. Scalability: presumed from the kinetic regime growth of the nanocrystals.
Italy; PCT