Royal Society of Chemistry praises HZB team’s paper on hybrid perovskite structures
T-x phase diagram has been created for MAPb(I,Br)3 for the first time. It was revealed that the phase transition temperature of the iodine-rich mixed crystals drops as iodine content increases. © RSC Advances
For the 10th anniversary collection of its journal, the Royal Society of Chemistry (RSC) selected a paper published by a team from HZB. The paper from HZB is described as one of the most important contributions in the field of solar energy in recent years. The journal praised 23 selected papers that had been often cited or downloaded, and which offered a valuable advantage for further research.
The HZB paper focuses on the systematic characterisation of hybrid perovskites containing mixed halides (MAPb(I,Br)3). The samples of the mixed crystals were produced in powder form using a solvent-based synthesis method. The research team from HZB’s Department Structure and Dynamics of Energy Materials (SE-ASD) showed that the crystal structure of the mixed crystal compounds is temperature dependent. As the materials go through different phase transitions, they form either a tetragonal or a cubic perovskite structure depending on the temperature and chemical composition. Now, a comprehensive T-x phase diagram has been created for this solid solution series for the first time. It was revealed that the phase transition temperature of the iodine-rich mixed crystals drops as iodine content increases, which stabilises the cubic perovskite structure at room temperature.
For their temperature-dependent in-situ experiments, HZB’s team used the DIFFRACTION end station of the BESSY II beamline KMC-2. They additionally determined the band gap energy and studied the optoelectronic properties of these perovskite compounds (among other things using photoluminescence spectroscopy).
The results led to a fundamental structural characterisation of these mixed halide perovskite compounds. Although the study was based on powder-form materials, the insights gained on the temperature-dependent behaviour of these hybrid halide perovskites can be now be applied to thin-film materials like those used to create absorbers for thin-film solar cells.
The paper was authored by Frederike Lehmann as part of her doctoral thesis in the graduate school HyPerCell. Her thesis was supervised by Prof. Dr. Susan Schorr and Dr. Alexandra Franz from the HZB Department Structure and Dynamics of Energy Materials and by Prof. Dr. Andreas Taubert from Potsdam University. “The paper was an excellent team achievement, and we are delighted that the RSC chose to write about us,” says Susan Schorr.
Click here for the RSC Advances Anniversary Collection “Solar Energy
- MXene as a frame for 2D water films shows new propertiesAn international team led by Dr. Tristan Petit and Prof. Yury Gogotsi has investigated MXene with confined water and ions at BESSY II. In the MXene samples, a transition between localised ice clusters to quasi-two-dimensional water films was identified by increasing temperature. The team also discovered that the intercalated water structure drives a reversible transition from metallic to semiconducting behaviour of the MXene film. This could enable the development of novel devices or sensors based on MXenes.
- Lithium-sulphur batteries with lean electrolyte: problem areas clarifiedUsing a non-destructive method, a team at HZB investigated practical lithium-sulphur pouch cells with lean electrolyte for the first time. With operando neutron tomography, they could visualise in real-time how the liquid electrolyte distributes and wets the electrodes across multilayers during charging and discharging. These findings offer valuable insights into the cell failure mechanisms and are helpful to design compact Li-S batteries with a high energy density in formats relevant to industrial applications.
- Self assembling monolayer can improve lead-free perovskite solar cells tooTin perovskite solar cells are not only non-toxic, but also potentially more stable than lead-containing perovskite solar cells. However, they are also significantly less efficient. Now, an international team has succeeded in reducing losses in the lower contact layer of tin perovskite solar cells: The scienstists identified chemical compounds that self-assemble into a molecular layer that fits very well with the lattice structure of tin perovskites. On this monolayer, tin perovskite with excellent optoelectronic quality can be grown, which increases the performance of the solar cell.