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. An intriguing aspect that has emerged is the sensitivity of perovskite materials to strain.
Strain can be introduced in the thin films during the fabrication process, e.g. during the cooling from the annealing process due to a mismatch of the coefficient of thermal expansion between the perovskite and the substrate, as shown in the figure on the left (Xue, DJ., Hou, Y., Liu, SC. et al. Regulating strain in perovskite thin films through charge-transport layers, Nat. Commun. 2020, 11, 1514). The presence of strain can vary the optical and electrical properties of the perovskite material, and understanding the interplay between stress and perovskite properties is crucial for optimizing fabrication techniques, enhancing material stability, and ultimately advancing the performance of perovskite-based devices.
In this project, the student will employ a spin coater to deposit thin films of layered double perovskite onto several inorganic and organic substrates, adjusting the annealing temperature as part of the deposition process. This will introduce stress in the fabricated film. Then, measurements and analysis of the photoluminescence response of these films will be conducted. The student will establish a correlation between the stress introduced in the film and the changes in photoluminescence properties. This investigation has the potential to offer insights into the strain-dependent characteristics of these materials, with possible applications in optoelectronics, particularly LEDs.