Single-crystalline hybrid perovskites have important photoelectronic properties for advanced semiconductor devices, such as solar cells and photodetectors. However, neither the surface-enhanced Raman scattering (SERS) property nor the correlation between SERS and photoelectronic properties for single-crystalline perovskites have ever been studied. Here, for the first time, we observed a 10⁵ enhancement in SERS for 4-mercaptopyridine (MPY) adsorbed on a methylamine lead chlorine (MAPbCl₃) single crystal. Compared to the Raman spectrum of bulk MPY molecules, the b₂ mode of the MPY molecule was selectively enhanced. This is attributed to the charge transfer (CT) resonance mechanism at the interface between the single crystal and the adsorbed molecules, which benefit from the Herzberg–Teller contribution. UV–vis spectra demonstrated that the modification with the MPY molecules leads to the formation of a new interfacial transition state, which matches the excitation laser photon energy and results in a CT resonance process under 532 nm laser excitation. The MPY-modified MAPbCl₃ single crystal was further applied to a photoelectronic device, and the device I–V curve was collected under 532 nm laser irradiation. The results indicate that the MPY-modified MAPbCl₃ shows a clear photoelectronic response to the 532 nm light. This study establishes a correlation between the CT resonance-enhanced Raman and the photoelectronic responses of perovskite materials and provides guidance for future molecule-sensitized perovskite photoelectronic device studies.

中文翻译：

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电荷转移对单晶钙钛矿上吸附分子的共振增强拉曼散射的影响

单晶杂化钙钛矿对先进的半导体器件（例如太阳能电池和光电探测器）具有重要的光电特性。然而，对于单晶钙钛矿，既没有研究表面增强拉曼散射（SERS）性质，也没有研究SERS与光电性质之间的相关性。在这里，我们首次观察到吸附在甲胺铅氯（MAPbCl ₃）单晶上的4-巯基吡啶（MPY）的SERS增强10 ⁵。与大块MPY分子的拉曼光谱相比，b ₂MPY分子的模式被选择性地增强。这归因于单晶与被吸附分子之间的界面处的电荷转移（CT）共振机制，这得益于Herzberg-Teller的贡献。紫外可见光谱表明，MPY分子的修饰导致形成新的界面跃迁态，该界面跃迁态与激发激光的光子能量相匹配，并导致在532 nm激光激发下的CT共振过程。将MPY修饰的MAPbCl ₃单晶进一步应用于光电子器件，并在532 nm激光辐照下收集器件的I–V曲线。结果表明，MPY修饰的MAPbCl ₃显示出对532 nm光的清晰光电响应。这项研究建立了增强CT共振的拉曼与钙钛矿材料的光电响应之间的相关性，并为未来分子敏化钙钛矿光电器件的研究提供了指导。