Mixed-Chalcogen 2D Silver Phenylchalcogenides (AgE_1-EPh; E = S, Se, Te).

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Alloying is crucial for tuning semiconductor properties.
• Two-dimensional (2D) hybrid organic-inorganic silver phenylchalcogenides (AgEPh) offer tunable electronic and optical characteristics.
• Understanding alloy thermodynamics is key to material design.

Purpose of the Study:

• Investigate the thermodynamic stability and excitonic properties of mixed-chalcogen alloys of 2D AgEPh (E = S, Se, Te).
• Determine miscibility and phase behavior in AgSPh-AgSePh, AgSPh-AgTePh, and AgSePh-AgTePh systems.
• Correlate alloy composition with optical properties and electron-phonon interactions.

Main Methods:

• Experimental characterization: structural and optical techniques.
• Computational modeling: Density Functional Theory (DFT) calculations.
• Thermodynamic analysis: comparing mixing energy with entropy of mixing.

Main Results:

• AgSePh-AgTePh forms homogeneous alloys (AgSe_1-TePh), while AgSPh-AgSePh and AgSPh-AgTePh exhibit miscibility gaps.
• DFT predicts alloying is energetically unfavorable but comparable to entropy-driven mixing.
• AgSePh-AgTePh alloying is thermodynamically preferred due to matching crystal structures, unlike other systems.

Conclusions:

• Thermodynamics of 2D silver phenylchalcogenide alloys are governed by crystal structure and mixing energetics.
• Homogeneous AgSe_1-TePh alloys show tunable UV-Vis absorption.
• Alloy composition influences exciton behavior and electron-phonon interactions in these hybrid semiconductors.