University of Utah researchers recently used temperature-dependent absorption and emission spectroscopy, as well as X-ray diffraction, to study the phase transition behaviors of Ruddlesden-Popper (RP) metal-halide hybrid perovskites. RP perovskites are a type of layered material made from alternating sheets of inorganic and organic components. These materials are potentially ideal for several applications, including light-emitting diodes (LEDs), thermal energy storage and solar-panel technology.
Image from: Matter
A phase transition is a discrete change from one state of matter to another (such as ice to liquid water). Some substances, including water and perovskites, have multiple solid states with different properties. The U of Utah team demonstrated a connection between phase transitions and the material’s emissive properties. This introduces a form of dynamic control, or tunability, that offers multiple benefits for technological applications. Specifically, because perovskites contain both organic and inorganic components, the organic layers undergo phase transitions that influence the structure of the inorganic layers. The interplay of the organic and inorganic layers drastically alters the material’s properties.
“There are these almost greasy chains that kind of crystallize together. When you hit a certain temperature, those will essentially melt and become more disordered,” said Assistant Professor Connor Bischak, senior author on the new study. “The melting process influences the structure of the inorganic component, which controls how much light is emitted from the material and its wavelength.”
Through this study, the Bischak Lab observed differences in distortion within the inorganic component. These distortions result in controllable changes to the light’s wavelength, which is a crucial part of designing tunable LEDs and other electronic devices.
“Perovskites can be manipulated easily at the molecular level,” Bischak added. “The emission wavelength can be tuned from ultraviolet up to near-infrared.”
This tunability is a major strength for applications in energy storage technology. Thermal energy storage, in particular, is an exciting area for perovskite applications since they can be tuned to have specific properties by adjusting their temperature. Additionally, perovskites can undergo repeated thermal cycling with minimal degradation, ensuring greater efficiency and longevity compared to current industry-standard materials.
Moreover, perovskites offer powerful advantages for next-generation solar cell technology. While silicon has long been the standard material for solar cells, it faces limitations due to its energy-intensive manufacturing process and ongoing supply chain issues. In contrast, perovskites are solution-processable materials. “What that means is you basically dissolve all these precursor chemicals in a solvent, and then you can make your solar cell almost like printing with ink,” Bischak said. “It produces an efficient solar cell material that’s better than silicon.”
An added benefit is that existing silicon solar cell technology can be retrofitted with perovskites to significantly increase their efficiency.
As the demand for cleaner and more adaptable energy solutions continues to rise, perovskite materials offer a promising path forward. Their unique tunability, ease of processing, and compatibility with current technologies make them a strong candidate for innovation in energy solutions.
This recent study directly links structural dynamics to reversible changes in the optical properties of 2D perovskites and examines the potential for dynamically switchable optoelectronics with hybrid materials.
