Environmentally friendly and sustainable energy production is one of the greatest tasks of our time in order to meet the challenges of climate change and the increasing global energy demand. In addition to the classic photovoltaic modules made of silicon, new materials and technologies have emerged in recent years as alternatives that enable transparent, flexible and lightweight modules. In particular, solar cells based on lead-halide perovskites and nanocrystals containing heavy metals have recently experienced considerable increase in their power conversion efficiencies and could open up these new areas of application. However, the high concentration of toxic and environmentally harmful elements such as lead or cadmium in these solar cells makes it questionable to what extent widespread use is even possible against the background of EU-wide directives limiting such harmful compounds. Moreover, the use of these toxic materials could become a significant issue at their end of life, when the modules would need to be disposed of, potentially harming both the environment and the society.

Basis for the production of efficient solar cells and light sensors

The GreenDots research project funded by BMBF focuses on the production and application of nanocrystalline materials, so-called quantum dots, which do not require the usual heavy metals such as lead or cadmium and are therefore more environmentally friendly. By varying the chemical synthesis conditions, the composition and size of the quantum dots can be adjusted, thus tuning the optical and electronic properties of the semiconducting nanomaterials to fit the desired application. After transferring the nanocrystals into concentrated, stable dispersions (inks), the fabrication of high-quality thin films is investigated using solution-based deposition and printing techniques. These processes, in turn, form the basis for the fabrication of efficient solar cells and sensitive light sensors.

Beyond the focus on increasing the performance and efficiencies of the devices, the project also investigates the reliability and stability of the materials and solar cells. To ensure that the production of these nanomaterials itself is also environmentally friendly, the focus within the research project is on the adaptation of environmentally compatible starting materials and solvents in the syntheses, a minimization of resource and energy consumption in the production and processing, as well as on a possible recyclability of the nanocrystals from disused components. Based on these data, the entire life cycle of the electronic components will be analyzed in terms of resource use and environmental impact in order to quantify and evaluate the economic added value of this technology at an early stage. This research project thus makes an important contribution to the development of materials for high-performance photovoltaics that conserve resources and protect the environment.