Scanning tunneling microscopy/spectroscopy is applied herein to study the pristine and potassium (K)-doped single-layer p-quaterphenyl (P4P) films grown on the Au(111) substrate at the molecular level. Abundant complex structural and electronic phases are induced by various K doping. The Fermi-level pinning effect is observed at a low doping level. On the contrary, K₃P4P exhibits intriguing versatile phases and properties because charge carriers are effectively doped in. For example, two kinds of molecular vibration modes with energies below 100 meV are observed, indicating a possible strong electron-phonon coupling. The splitting of the lowest unoccupied molecular orbital state in K₃P4P illustrates an electronic correlation effect, and its strength varies for four different K₃P4P phases with different structures. In addition, the appearance of a Kondo resonance on the molecular vacancy/impurity implies a local molecular magnetic moment. Our results demonstrate that the complex electronic properties of an alkali metal-doped P4P/Au film stem from the existence of many competing interactions, such as electron-electron correlations and electron-vibration coupling, which can be effectively tuned via variable carrier doping and molecular structure. Our work also opens new routes toward engineering novel molecular devices and creating new electronic phases in strongly correlated molecular materials.

本文将扫描隧道显微镜/光谱学应用于研究在Au（111）衬底上以分子水平生长的原始和钾（K）掺杂的单层对-四苯基（P4P）薄膜。各种K掺杂可诱导大量复杂的结构相和电子相。在低掺杂水平下观察到费米能级钉扎效应。相反，由于电荷载流子被有效地掺杂，K ₃ P4P具有吸引人的多功能相和性能。例如，观察到两种能量低于100 meV的分子振动模式，表明可能存在强的电子-声子耦合。K _3中最低的未占据分子轨道状态的分裂P4P说明了一种电子相关效应，其强度在具有不同结构的四个不同的K ₃ P4P相中有所不同。另外，在分子空位/杂质上近藤共振的出现暗示了局部分子磁矩。我们的结果表明，掺杂碱金属的P4P / Au膜的复杂电子性能源于许多竞争性相互作用的存在，例如电子-电子相关性和电子-振动耦合，可以通过可变载流子掺杂和分子有效地调节这种相互作用。结构体。我们的工作还为工程化新型分子装置和在高度相关的分子材料中创建新的电子相开辟了新途径。