In polycrystalline thin films of small organic semiconductor molecules, the precise molecular packing determines the film’s intrinsic charge transport properties and consequently the electrical performance in thin-film devices such as organic thin film transistors (OTFTs). Synchrotron X-ray scattering is a powerful method to extract molecular packing details in such films that cannot currently be obtained by any other available technique. It can, in fact, be used to analyze films as thin as a fraction of a single monolayer. We employ a combination of Grazing Incidence X-ray Scattering (GIXS) and advanced crystallographic refinement calculations to obtain a detailed picture of the molecular packing at the emiconductor/dielectric interface in OTFT thin films. The capability to obtain the detailed molecular packing with this approach is highlighted at the example of several organic semiconductor thin film systems, including high performance solution-deposited materials, both n- type and p-type, that exhibit field effect mobilities > 3 cm^2/Vs in the respective OTFT devices.
In polycrystalline thin films of small organic semiconductor molecules, the precise molecular packing determines the film’s intrinsic charge transport properties and consequently the electrical performance in thin-film devices such as organic thin film transistors (OTFTs). Synchrotron X-ray scattering is a powerful method to extract molecular packing details in such films that cannot currently be obtained by any other available technique. It can, in fact, be used to analyze films as thin as a fraction of a single monolayer. We employ a combination of Grazing Incidence X-ray Scattering (GIXS) and advanced crystallographic refinement calculations to obtain a detailed picture of the molecular packing at the emiconductor/dielectric interface in OTFT thin films. The capability to obtain the detailed molecular packing with this approach is highlighted at the example of several organic semiconductor thin film systems, including high performance solution-deposited materials, both n- type and p-type, that exhibit field effect mobilities > 3 cm^2/Vs in the respective OTFT devices.
