perovskites-NMR · Atomic-level characterization of multi-component perovskite materials for optoelectronic applications

Atomic-level characterization of multi-component perovskite materials for optoelectronic applications

About a decade ago, metal halide perovskites (MHPs) emerged as a new class of materials promising more efficient solar cells and light emission diodes (LEDs). Unlike silicone solar cells, they are easy to process in solution, allowing strategies such as solar cell printing. Perovskites can be represented by the general formula ABX3, where A is a small organic or inorganic component with a positive charge, B is a metal such as lead or tin, and X is a halogen, such as iodine, bromine or chlorine. In state-of-the-art solar cells, the “A”, “B” and “X” components are mixtures of chemical species and this strategy, referred to as compositional engineering, is what has led to solar cell efficiencies exceeding 25%. Generating more solar power and doing so more efficiently is essential to combat the ongoing climate crisis caused by burning fossil fuels. Halide perovskite solar cells and light-emitting devices are being intensely developed in academic institutions worldwide to diversify the available optoelectronic technologies and to constructively contribute to resolving the climate crisis. However, the two major challenges associated with MHP photovoltaics are their poor long-term stability and the toxicity of lead. The first issue is being tackled by developing ever complex chemical compositions to improve humidity and light resistance of the perovskite light absorber. The toxicity of lead can be combatted by developing lead-free light absorbers using metals such as tin, silver and bismuth. These materials come with other problems – they are not as efficient as lead halide perovskites and tin halide perovskites are particularly sensitive to degradation in ambient air. While new MHP compositions of arbitrary complexity can be readily prepared and tested, the main challenge is that our understanding of these new materials at the atomic level is insufficient. In order to understand the mechanisms of degradation as well as performance and stability improvements, it is necessary to look at the smallest building blocks of the structure. Until very recently, there were no methods that would allow studying MHPs at those small scales. Nuclear magnetic resonance (NMR) spectroscopy is a perfectly suited non-destructive method to address this challenge as it provides information on structure of materials at the atomic level. This project employs a combination of NMR and advanced optical spectroscopies to provide structure-property relationships in a broad range of materials developed as solar cell and LED materials today, thereby improving our understanding on how to rationally prepare more efficient optoelectronic materials. In conclusion, the action has provided an unparalleled insight into the atomic-level structure of a highly technologically relevant class of materials for sustainable energy.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз