Tuning Optical and Electronic Properties of MoS₂ and MoSe₂ Crystals via External Pressure: Structural Analysis and Device Implications

Layered transition metal dichalcogenides (TMDs), particularly molybdenum disulfide (MoS₂) and molybdenum diselenide (MoSe₂), have garnered substantial attention due to their tunable bandgaps, strong excitonic effects, and layered structures. These unique properties render those promising candidates for next-generation optoelectronic and nanoelectronic devices. In this study, we investigate the structural and optoelectronic modulation of high-purity single crystalline MoS₂ and MoSe₂ under externally applied pressure up to 35 GPa using a diamond anvil cell (DAC) setup. Through in-situ synchrotron X-ray diffraction (XRD), Raman spectroscopy, and photoluminescence (PL) measurements, we observe pressure-induced lattice compression, phonon mode shifts, exciton quenching, and bandgap narrowing, without any evidence of structural phase transition up to the studied pressure range. These findings offer insight into pressure-driven band structure engineering and highlight the potential of TMDs for pressure-tunable optoelectronic devices.