Thermoelectric properties of organic thin films enhanced by π–π stacking

Abstract Thin films comprising synthetically robust, scalable molecules have been shown to major potential for thermoelectric energy harvesting. Previous studies of molecular thin-films tended focus on massively parallel arrays discrete but identical conjugated wires assembled as a monolayer perpendicular the electrode surface and anchored via covalent bond, know self-assembled monolayers. In these studies, optimise properties thin-film there has trade-off between synthetic complexity components film performance, limiting opportunities materials integration into practical devices. this work, we demonstrate an alternative strategy enhancing performance thin-films. We built up series films, controlled thickness, where basic units—here zinc tetraphenylporphyrin—lie electrodes are linked π – stacking. compared three commonly used fabrications routes characterised resulting with scanning probe computational techniques. Using Langmuir-Blodgett fabrication technique, successfully enhanced thermopower plane ZnTPP multilayer by factor 10, relative monolayer, achieving Seebeck coefficient −65 μ V K −1 . Furthermore, electronic transport system, was observed follow tunnelling regime multi-layered efficiency comparable most systems. thermal microscopy characterisation shows 7 decrease in conductance increasing thickness from multilayer, indicating stacked junction.