Modelling charge transport in organic semiconductors

• Main Author: Daniels, Alex
• Other Authors: Walker, Alison
• Published: University of Bath 2017
• Subjects: 537
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720663

The search for energy efficient materials is more important now than it has ever been before. As such, computational models that investigate charge transport properties of materials have grown into an incredibly vast field of research. These models require knowledge of the structures that materials form, along with their electronic structure characteristics. The primary focus of this work was to develop a model, based on an existing model used for investigating protein structures, that would allow for a large number of molecular morphologies to be generated. This model allows for a full atomistic morphology to be generated (which is important for charge transport simulations) at a fraction of the computational cost of conventional techniques by treating molecules as a series of rigid sections. The model has been validated using two well documented test case morphologies, the first, Buckminsterfulerene due to its spherical nature, and the second, hexane due to its flexibility. After validation the model has been used to generate morphologies for a subset of dithiophene derivatives that our industry sponsor was interested in. Charge transport simulations were then performed on these morphologies and these are the key result of this research. We have shown clear trends in how varying the composition of the sidechains of these dithiophene based molecules directly affects the mobilities they exhibit and thus, that charge transport is incredibly sensitive to morphology.