FREENERGY · Lead-free halide perovskites for the highest efficient solar energy conversion

Achieving zero net carbon emissions by the end of the century is the challenge for capping global warming. The largest share of carbon emissions belongs to the production of electric energy from fossil fuels, which renewable energies are progressively replacing. Sunlight is an ideal renewable energy source since it is most abundant and available worldwide. Photovoltaic solar cells can directly convert the sunlight into electric energy by making use of the photovoltaic effect in semiconductors. Halide perovskites are emerging crystalline semiconducting materials with among the strongest light absorption and the most effective electric charge generation needed to design the highest efficient photovoltaic solar cells. The PI has the ambition to reinvent halide perovskites as environmentally friendly photovoltaic material, aiming at:(i) Removing lead: state-of-the-art perovskite solar cells are based on lead, which is in the list of hazardous substances of the European Union. The PI will prepare new tin-based perovskites and prove them in the highest efficient solar cells.(ii) Solvent-free crystallisation: organic solvents drive the crystallisation of the perovskite in the most efficient solar cells. However, crystallising the perovskite without using solvents is more environmentally friendly. The PI will establish physical vapour deposition as a solvent-free method for preparing the perovskite and the other materials comprising the solar cell.(iii) Durable power output: the long-term power output defines the solar energy yield and thus the return on investment. The PI aims to make stable tin-based perovskites addressing the oxidative instability of tin directly.The quantified target of FREENERGY is demonstrating a tin-based perovskite solar cell with power conversion efficiency over 20% and stability for 25 years. The research strategy to enable this disruptive outcome comprises innovative perovskites formulations and unconventional supramolecular interactions