(262d) Exciton Diffusion in Quantum-Dot Thin Films

Colloidal quantum dots (QD), also known as semiconductor nanocrystals, are an intriguing material platform for solution-processable optoelectronic devices, such as solar cells, light-emitting diodes, thermoelectric modules, and flexible electronics. In QD thin films, the efficient movement of charge, heat, and excitonic energy is intimately linked to the QD surface chemistry and the amount of structural or energetic disorder in the material. In excitonic solar cells, the efficient diffusion of excitons to charge-separating interfaces is central to device operation. On the other hand, exciton diffusion to quenching interfaces in light-emitting diodes is a process that can limit luminescence efficiency. While the diffusion of singlet and triplet excitons in organic semiconductors has been studied extensively, exciton diffusion in colloidal QD thin films remains largely unexplored. In this talk, I will detail my group’s combined experimental and computational efforts to obtain a deeper understanding of excitonic energy transport phenomena in colloidal QD materials. These efforts include spectrally-resolved transient photoluminescence spectroscopy, photoluminescence quenching, time-resolved optical imaging, and kinetic Monte Carlo simulation.