Much research has been conducted into perovskite crystal compounds for use in solar cells in recent years, which are more energy efficient and cheaper than conventional silicon cells. An international team led by Stefan Weber at the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found that it is possible to make the electrons within the cell move quicker by altering the microscopic structures of the compound at the manufacturing stage.
The enquiry began five years ago when the research group identified “stripe shaped domains” within the tiny structures of the cells under examination with a piezo force microscope (PFM). Their recent research has shown that these so-called “ferro elastic twin domains” (which form spontaneously during fabrication of the perovskite by mechanical stress) act as “tiny highways” for electrons, propelling them forwards.
By using photoluminescence microscopy, Weber’s team discovered that the electrons travel 50 to 60 percent faster along the striped domains, than perpendicular to the domains. "If we were able to make the stripes point directly to the electrodes, a perovskite solar cell could become much more efficient," says researcher Ilka Hermes in a . She is the first author of the study which was published in the journal Energy Environmental Science. This could be achieved by putting the crystals under mechanical stress during production.
The discovery at MPI-P could not only improve solar cells – which are a vital component in Germany’s transition to a low-carbon economy – but the efficiency of other optoelectronic applications such as light-emitting diodes (LEDS) and radiation detectors.