High-Entropy Oxides for Electronic Applications: Present and Future

HEMs represent a class of materials characterized by the incorporation of a minimum of five distinct elements within a single-phase lattice structure. This incorporation serves to elevate configurational entropy, a measure of entropy arising from the mixing of dissimilar elements, thereby engendering the emergence of unique material properties. There exist various subtypes, with high-entropy alloys and high-entropy ceramics being the most prominent among them. While alloys are typically unified within a single lattice structure, ceramics exhibit a more complex arrangement, often comprising multiple sublattices, including cationic and anionic sublattices. Consequently, when evaluating configurational entropy, one must scrutinize these sublattices independently. The combination of dissimilar elements or ions, characterized by disparities in size, electronegativity, and other factors, induces lattice distortions and intricate inter-element interactions. This interplay initiates a cascade of electronic, physical, chemical, and structural effects within the material.<br/>Given that the synthesis of many high-entropy materials typically results in powders, and the production of well-ordered crystalline layers is possible only in specific cases or with significant effort, a structuring technique capable of yielding the desired results with powders is imperative.<br/>This presentation introduces printing techniques as a versatile technique for structuring high-entropy materials and delves into current applications in electronic devices and systems. More specifically the talk will discuss the properties of semiconducting high entropy oxides as revealed by Hall mobility measurements of flurite structures. While the mechanism is still unknown we show that mobility can be improved by the number of constituent elements. These materials can have a great potential for high performance absorbance layers. As a second example we will show HE Metal organic frameworks (HEMOFs) displaying interesting properties as active materials in memristive devices. Wet chemistry approaches at room temperature are used to fabricate Prussian blue HE MOFs with at least five different elements. The HE MOFs can easily be inkjet printed and keep their molecular structure after pattering which is important for device fabrication.<br/>In conclusion we believe that while many mechanisms underpinning the enhancement of various properties remain to be discovered, there exist great prospects for employing high-entropy materials as active materials in components of electronic systems