Solid-state processing of organic semiconductors

Solid-state processing of conjugated small molecular, oligomeric and polymeric compounds was conducted. Solid, powdered material was placed in a hot press, followed by compression molding well below the melting temperatures of the species, typically at pressures of approximately 10 30 kN cm^-2. In order to investigate whether or not solid-state processing deteriorated electronic properties of the semiconductors, time-of-flight (TOF) photoconductivity experiments were conducted, which allow determination of bulk charge transport across thin film architectures. A typical small-molecular compound (6T) and two polymeric species P3HT and the liquid-crystalline PBTTT-C₁₆, were selected. It was demonstrated that bulk carrier mobilities derived from TOF studies did not deteriorate, but in some cases actually could be significantly enhanced when compared to conventionally processed structures. Interfacial charge transport both for electrons and holes was not affected, despite processing the organic semiconductors in light and air.