Disclosed are organic semiconductor materials, including mixtures of relatively low molecular weight aromatic ring compounds, in which at least one nitrogen atom or oxygen atom is present as a heteroatom in the aromatic ring compounds for forming hydrogen bonds between the heteroatom(s) and adjacent molecules and thereby increase intermolecular stacking. Organic semiconductor layers formed using such organic semiconductor materials will, accordingly, exhibit increased intermolecular stacking and associated improvements in one or more electrical properties of the semiconductor layer. Organic thin film transistors incorporating such organic semiconductor layers will tend to exhibit improved transistor properties including, for example, increased carrier mobility and reduced off-state leakage current. Further, the organic semiconductor layers may be manufactured using conventional room temperature processes, for example, spin coating or printing, thereby simplifying the fabrication process.