Organic semiconductors are promising optoelectronic materials with strong light absorption and excitonic effects. For these systems, the interplay between inter- and intra-molecular interactions results in a complex behavior of excitons that is not yet well-controlled in devices. Here, we utilize first-principles theory to understand the role of inter-molecular orientation on the nature and energy of excitons within ordered organic materials. For a series of acene derivatives in the bulk crystalline phase, highly accurate many-body perturbation theory calculations predict significant exciton binding energies and charge-transfer character, which can be controlled through solid-state morphology or change of conjugation length. Additionally, we investigate the role of inter-molecular vibrational interactions on the optoelectronic properties of PTCDI-based molecular wires. Using a density functional theory analysis, we demonstrate that strong inter-molecular interactions lead to distinct vibrational, electronic, and optical properties. Overall, this work suggests a new strategy for design of new electronic and organic optoelectronic materials.