The structure of a tightly packed monolayer is the result of a delicate balance of moleculesubstrate and molecule-molecule interactions. Having studied the molecule-substrate interactions through isolated molecules in the previous section, we now complete the picture by investigating the interplay of molecule-substrate and molecule-molecule interactions in tightly packed structures. It is important to note that both interactions are not independent of each other. Understanding how these interactions interact is a necessary requirement to effectively manipulate the interface polymorphism using electric fields.