Alloy Engineering in Few‐Layer Manganese Phosphorus Trichalcogenides for Surface‐Enhanced Raman Scattering

Abstract

Manganese phosphorus trichalcogenides are widely used in the field of photocatalysis and magnetic studies due to their broadband gaps. Herein, an alloy engineering method for the few‐layer manganese phosphorus trichalcogenides (MnPS3–xSex, 0 ≤ x ≤ 3) in surface‐enhanced Raman scattering (SERS) is reported. A new strategy, with the coupling of exciton resonance (µex) and photoinduced charge transfer (PICT), is applied to screen out materials for SERS enhancement. According to the calculation of density functional theory, the bandgap of manganese phosphorus trichalcogenides (MnPS3) can be adjusted to match the band energy of Rhodamine 6G molecules by alloy engineering. Furthermore, a series of few‐layer MnPS3–xSex (0 ≤ x ≤ 3) are fabricated to study the PICT‐induced SERS behavior under resonance excitation. The good performance with a detection limit down to 10−9 m indicates that the synergistic resonances between µex and PICT are crucial to the enhancement.

Defect engineering in semiconductor-based SERS

“…85,86 In extension to TMDs, m ex resonance has also been achieved in trichalcogenide alloy MnPS x Se 1Àx by controlling the concentration of Se towards similar effects of band gap tuning. 87 In addition to the band gap, new energy states could be created due to various types of defects. Defect-induced disorders oen cause the formation of surface state levels (E SS ), [88][89][90] which is useful for inducing electron transition from the VB with lower excitation energy.…”

“… 85,86 In extension to TMDs, μ ex resonance has also been achieved in trichalcogenide alloy MnPS x Se 1− x by controlling the concentration of Se towards similar effects of band gap tuning. 87 …”

Surface Enhanced Raman Scattering Revealed by Interfacial Charge-Transfer Transitions

“…The obviously enhanced SERS performances in these TMD substrates are closely related to the abundant DOS near the Fermi level, which facilitates the exciton and CT resonances in the molecule-substrate system. In addition to the traditional family of TMDs, new types of metal chalcogens that exhibit attractive SERS activities, such as SnSe 2 nanoflakes 47 and few-layer manganese phosphorus trichalcogenides (MnPS 3 −x Se x , 0 ≤ x ≤ 3), 48 have also been developed, which also stem primarily from the CT-induced enhancement.…”

The origin of ultrasensitive SERS sensing beyond plasmonics

“…Among these 2D materials, the MnPS 2.4 Se 0.6 shows the largest Raman enhancement with a LOD of 10 -9 M due to its exciton resonance at 2.20 eV is very close to the energy of incident light (2.32 eV). This result indicates that the synergistic resonances between CT and exciton resonance are crucial to Raman enhancement in MnPS 2.4 Se 0.6 -R6G system (Fig.3)[96].…”