The perfect solar cell
Within a few years only, methylammonium lead iodide (MAPbI3), and later more advanced organic metal halide perovskites, have performed an unprecedented rally towards highest power conversion efficiencies. A team of six scientists at Karlsruhe Institute of Technology (KIT) has found evidence for ferroelectric domains in MAPbI3 thin-films. For their cutting-edge research, the team was awarded the Erwin-Schrödinger-Prize of the Helmholtz Association and the Helmholtz Foundation.
“Photovoltaics is a major element of power supply from renewable energy sources, which has a great potential in research and development – especially with regard to the materials applied,” said the President of KIT, Professor Holger Hanselka. “With its research that successfully combines optoelectronics and ceramic materials, the team of KIT decisively contributes to the further development of perovskite solar cells. The use of such novel materials in future solar cell generations will enhance the efficiency of the conversion of sunlight into electric power, even more so as the material is easy to process and inexpensive. The Erwin Schrödinger Prize is an outstanding appreciation for this work.“
What would a perfect solar cell look like? Besides a black visual nature for optimal light-harvesting, the perfect solar cell efficiently guides the photo-generated charge carriers out of the device to the electrodes, hence minimizing recombination losses. A multi-disciplinary team at the new Material Research Center for Energy Systems (MZE) has produced evidence that MAPbI3 is ferroelectric. As such, MAPbI3 thin-films spontaneously form alternating polar domains with a typical width of 90 nm. “The microscopic electrical fields within the domains may help to separate the photo-generated charge carriers and hence to reduce their recombination” says Holger Röhm, doctoral researcher at the MZE. Together with Tobias Leonhard and Alexander D. Schulz, Röhm has explored the microscopic electric fields of the ferroelectric MAPbI3 and its microstructure.