Speaker: Dan Congreve Faculty Host: Prof. James Teherani
Abstract: Controlling excitons, charge, and spin at the nanoscale has opened up numerous exciting opportunities. In particular, transfer between different material systems has allowed us to uncover novel physics and applications. In this talk, I will show how we can use this control to build the next generation of solutions to the challenges facing us.
First, photon upconversion and downconversion allow us to convert between colors of light while conserving energy. We demonstrate that controlling exciton flow between organics and colloidal nanocrystals allows us to achieve quantum efficiencies greater than 100% utilizing downconversion and infrared-to-visible harvesting using upconversion. Further, by pairing upconversion with a photocatalyst, we can perform photochemistry using infrared light instead of visible, opening the door for in vivo applications.
Similar opportunities can be found in perovskites: these materials have great potential, but commercialization opportunities are currently limited by poor stability and the low quality of blue emitters. Here, we show that controlling energy transfer between an atomic dopant and the perovskite host allows for greatly improved luminescence and stability, providing an important step towards commercializing perovskite devices.
Bio: Dan Congreve received his B.S. and M.S. from Iowa State in 2011, working with Vik Dalal studying defect densities of nano-crystalline and amorphous silicon. He received his PhD from MIT in 2015, studying under Marc Baldo. His thesis work focused on photonic energy conversion using singlet fission and triplet fusion as downconverting and upconverting processes, respectively. He then studied perovskite nanoplatelets and their applications as a postdoc with Will Tisdale before joining the Rowland Institute in August 2016. His current research interests focus on understanding charge, exciton, and spin transport at the nanoscale and using that understanding to construct novel devices.