Layered 2D hybrid perovskites are composed of organic spacer layers connecting adjacent perovskite slabs made of octahedra, where a monovalent MI (1+) and a trivalent MIII (3+) cation coordinate six halides and are ordered in an alternating fashion. These materials have attracted considerable interest due to their unique optoelectronic properties and highly modular structure that can be tailored by altering both organic and inorganic components. It would be of interest to control these effects on the potential barrier width without changing the perovskite composition, which can be achieved by relying on their mechanical properties and responsiveness to external stimuli, such as pressure.
In a previous study,1 we found that applying pressure ranging from ambient to 0.35 GPa, we could induce a red-shift of the bandgap energy up to 60 meV for some layered 2D perovskites, as shown in the picture on the left. However, we have observed that when the organic spacer contains long alkyl chains, there is no shift in the bandgap energy.
Within this project, the student will learn how to measure the pressure-dependent transmittance of perovskite thin films using a hydrostatic pressure cell (figure on the right). The student will explore the pressure response exhibited by various layered 2D perovskites featuring long alkyl chains as spacers and will investigate if the process is reversible, and whether a threshold of irreversibility exists. Furthermore, the student will acquire skills in data processing to establish the correlation between pressure and the bandgap of these materials. The measurements will take place at AMOLF in the group of Prof. Bruno Ehrler, while the data analysis will be performed at the VU.
1 L.A. Muscarella et al., Reversible Pressure-Dependent Mechanochromism of Dion–Jacobson and Ruddlesden–Popper Layered Hybrid Perovskites. Adv. Mater. 2022, 34, 2108720