Kinetics Control of Mithrene Formation in a High-Pressure Inert Environment: A Robust Solvent-Free Route to Superior-Quality Films

Metal organic chalcogenolates (MOCs) constitute a promising class of materials for optoelectronic applications owing to their unique 2D layered hybrid structure and inherent environmental stability. Among these materials, mithrene (silver phenylselenolate, AgSePh) is particularly compelling because of its sharp blue emission and notable anisotropic excitonic properties. However, conventional solvent-assisted mithrene synthesis methods are often associated with the introduction of chemical complexities as well as compromised film quality. Addressing these limitations, this study provides a robust solvent-free strategy for synthesizing high-quality mithrene thin films through precise pressure and temperature control in an inert gas environment, leading to optimized reaction kinetics. Comprehensive characterization through grazing incidence wide-angle X-ray scattering (GIWAXS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, and photoluminescence (PL) spectroscopy revealed that the resulting films possess greatly improved crystallinity, enhanced excitonic absorption, and significantly greater PL emission than their solvent-processed counterparts. Notably, a previously unreported excitonic feature (X_α) was identified, possibly originating from the high structural coherence along the out-of-plane direction achieved through our method. This study not only provides an advanced solvent-free route for high-quality MOC thin film fabrication but also unlocks avenues for their broader integration into next-generation optoelectronic devices, semiconductors, and catalysts.