Rational control of molecular ordering on surfaces and interfaces is vital in supramolecular chemistry and nanoscience. Here, a systematic scanning tunneling microscopy (STM) study for controlling the self-assembly behavior of alkoxylated benzene (B-OC(n)) molecules on a HOPG surface is presented. Three different phases have been observed and, of great importance, they can transform to each other by modifying the solute concentration. Further studies, particularly in situ diluting and concentrating experiments, demonstrate that the transitions among the three phases are highly controllable and reversible, and are driven thermodynamically. In addition, it is found that concentration-controlled reversible phase transitions are general for different chain lengths of B-OC(n) molecules. Such controllable and reversible phase transitions may have potential applications in the building of desirable functional organic thin films and provide a new understanding in thermodynamically driven self-assembly of organic molecules on surfaces and interfaces.

A vacuum evaporator is widely used for generating atomic/molecular beams for thin film deposition, and conventionally must be mounted to a vacuum chamber with an upwards angle from the horizontal. In this article, we report a novel kind of evaporator that can be mounted at an arbitrary angle for organic materials. The crucible of the evaporator here is designed to keep the loaded organic materials from falling. The morphology and electrical characteristics of pentacene thin film organic field effect transistors on trichloro(octadecyl)silane modified SiO 2 are characterized and compared for commercial and arbitrary mounting angle evaporators. Pentacene films deposited from both evaporators exhibit similar morphology and domain size characterized by atomic force microscope, as well as similar mobility, threshold voltage, and on/off ratio. The results can be used to develop a new configuration for an organic vacuum deposition system, which allows the positioning of shadow masks directly on substrates and thus avoids deformation, enabling fabrication of organic electronics for high resolution over large areas.

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Scanning tunneling microscopy is used to systematically study how to control the self‐assembly behavior of alkoxylated benzene molecules on a HOPG surface. On page 2284, Q. Li, Y. S. Xie, L. F. Chi, and co‐workers observe three different phases which can transform into each other by modifying the solute concentration. These transitions are highly controllable, reversible, and are driven thermodynamically. This systematic study not only provides candidate methodologies for approaching uniform molecular patterns on surfaces and interfaces, but is also valuable for fundamental physical interest.