The realization of novel electronic devices based on 2D materials, i.e., field-effect transistors, has recently stimulated a renewed interest regarding ultrathin fluoride epitaxial films. Thanks to their chemical and dielectric properties, ionic fluorides could have the potential to be used as insulators in many applications that require high processing control down to the nanoscale. Here we provide a review of some of the principal results that have been achieved in the past decades regarding the controlled growth of epitaxial fluorides on different types of materials relevant for electronics. The aim is to provide a concise summary of the growth modes, crystallinity, film morphologies, and chemical interactions of different types of fluorides on different type of substrates, highlighting the possibilities of applications and the future perspectives.

Cooperative phase transitions in organic crystals are attracting growing interest due to their reversible, diffusionless nature, their ability to generate macroscopic dynamic phenomena, and their strong influence on the physicochemical properties of molecular materials relevant to organic electronics. Yet, the microscopic mechanisms governing these lattice‐ and disorder‐driven transformations remain only partially understood. Because phase transitions amplify electron–phonon interactions by pushing low‐frequency modes into the anharmonic regime and reorganizing molecular packing within a few kelvins, they offer a unique opportunity to directly probe lattice–electronic coupling in organic semiconductors. Here, we investigate single crystals of 2,7‐di‐tert‐butyl‐[1]benzothieno[3,2‐b]benzothiophene (ditBu‐BTBT), a high‐performance organic semiconductor undergoing a diffusionless polymorphic transition near 70°C, to reveal how its electronic landscape, specifically the distribution of electronic states and optical bandgap, evolves across a cooperative phase transition. Variable‐temperature soft x‐ray reflectivity at the carbon K‐edge and UV–vis absorption spectroscopy show the order–disorder transition, evidenced by energy shifts of specific resonances attributed to increased dynamics of the lateral tert‐butyl groups, which become intramolecularly disordered at high temperature. Concurrently, the optical bandgap increases, reflecting reduced intermolecular interactions and band dispersion. These results directly demonstrate how cooperative polymorphic transitions modulate the electronic structure of organic semiconductors.

We present a comparative soft x‐ray absorption spectroscopy (XAS) study of the sulfur L ₂ , ₃ and molybdenum M ₂ , ₃ absorption edges in MoS ₂ prepared by different fabrication routes, including bulk crystallization, mechanical exfoliation, chemical vapor deposition (CVD), and ionized jet deposition (IJD). The S L ₂ , ₃ edges reveal pronounced differences in pre‐edge and main‐edge fine structure that sensitively reflect the degree of structural order, dimensionality, and electronic hybridization between S 3p and Mo 4d states. Bulk, exfoliated, and CVD‐grown samples exhibit well‐resolved multiple features characteristic of layered and ordered two‐dimensional (2D) MoS ₂ , whereas as‐deposited IJD‐grown films display broadened, weakly structured spectra consistent with an amorphous phase and poorly defined stoichiometry. Upon moderate annealing at 250°C, IJD‐grown films develop clear spectral signatures of layered MoS ₂ , indicating the formation of an ordered crystalline 2H‐MoS ₂ phase. Complementary analysis of the Mo M ₂ , ₃ edges shows a concomitant narrowing and energy shift of the M ₃ feature toward values typical of well‐ordered 2D MoS ₂ . These results demonstrate that S L ₂ , ₃ and Mo M ₂ , ₃ XAS provide a sensitive probe of synthesis‐dependent electronic structure in MoS ₂ and confirm IJD as a viable, low‐temperature route to electronically ordered 2D MoS ₂ phases.