Perovskite Mediated Vibronic Coupling of Semiconducting SERS for Biosensing

Improving charge transfer efficiency via vibronic coupling is vital to the performance of semiconducting surface-enhanced Raman spectroscopy (SERS). Previous attempts have focused on defects-based metastable-state assisted band structure matching strategy to enhance vibronic coupling. However, defect-related charge transfer transitions can be easily deteriorated due to enhanced phonon-assisted relaxation upon continuous laser irradiation. Herein, perovskite-based steady-state assisted band structure matching strategy is proposed to enhance vibronic coupling within perovskite-molecule charge transfer complex, leading to remarkable Raman enhancement up to 5.9 × 10⁶. Particularly, vibronic coupling can be modulated by tuning valence band position and introducing ultrathin Au coating, which allows selective enhancement of molecules with different band structures, including narrow-bandgap molecules and wide-bandgap molecules. Importantly, based on intrinsically stable conduction band and valence band states, this system achieves ultrahigh photostability, preserving 91.3% of the original intensity after 50 000 s of irradiation. This system also provides an outstanding tool for trace molecular detection, allowing sensitive and selective identification of 9 types of gastric cancer related aldehydes, which enables distinguishing the breath of gastric cancer patients from healthy controls with a discriminatory accuracy of 81.09%. This study is anticipated to shed new light into the future strategy design of efficient and stable semiconducting SERS.