Imaging charge transfer dynamics in nanomaterials using electron donor/acceptor modified AFM tips

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In this award, funded by the Chemical Measurement and Imaging Program of the Division of Chemistry, Professor Tianquan Lian of Emory University and his postdoctoral, graduate and undergraduate student researchers will be supported to investigate the feasibility of imaging charge transfer dynamics in nanomaterials using specially modified atomic force microscopy (AFM) tips. Prof. Lian and his research group will attach quantum dots to the AFM tips and will measure the photoinduced charge transfer between the modified tip and the probed surface. The goal of this research is to develop a better understanding of the photophysical process taking place at the boundaries in nanomaterials used in solar energy conversion.Atomic force microscopy methods use contact between a nanometer-scale probe and a surface to measure the changes in morphology of the probed surface. The probe is able to measure differences in the physical properties (e.g. hardness, softness) of the underlying surface at the nanometer (or smaller) length scale. Prof. Lian and his group are attempting to build an AFM probe that will be able to do what the AFM does, except by measuring differences in the rate of photoinduced charge transfer between the modified probe tip and the underlying surface. The goal is to develop the ability to measure the photophysical/electrical properties of nanoscale materials with the same resolution that can be obtained with AFM methods. The students working on this project will gain useful experience in developing cutting-edge analytical spectroscopy tools that will be useful for evaluating and characterizing technologically useful materials. As part of this work, Prof. Lian will continue his exemplary efforts at encouraging students from underrepresented groups to pursue careers in the sciences.