title: Coherent two-dimensional photocurrent spectroscopy in a PbS quantum dot photocell.
abstract: Recently there has been growing interest in the role of coherence in electronic dynamics. Coherent multidimensional spectroscopy has been used to reveal coherent phenomena in numerous material systems. Here we utilize a recent implementation of coherent multidimensional spectroscopy--two-dimensional photocurrent spectroscopy--in which we detect the photocurrent from a PbS quantum dot photocell resulting from its interactions with a sequence of four ultrafast laser pulses. We observe sub-picosecond evolution of two-dimensional spectra consistent with multiple exciton generation. Moreover, a comparison with two-dimensional fluorescence spectra of the quantum dots demonstrates the potential of two-dimensional photocurrent spectroscopy to elucidate detailed origins of photocurrent generating electronic state coherence pathways. Since the measurement is based on detecting the photocell current in situ, the method is well suited to study the fundamental ultrafast processes that affect the function of the device. This opens new avenues to investigate and implement coherent optimization strategies directly within devices.
authors.affiliation: Department of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden.
authors.forename: Khadga J
authors.initials: KJ
authors.lastname: Karki
authors.affiliation: Oregon Center for Optics and Department of Chemistry &Biochemistry, University of Oregon, Eugene, Oregon 97403, USA.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Widom
authors.affiliation: Department of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden.
authors.forename: Joachim
authors.initials: J
authors.lastname: Seibt
authors.affiliation: Materials Science Institute and Department of Chemistry &Biochemistry, University of Oregon, Eugene, Oregon 97403, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Moody
authors.affiliation: Materials Science Institute and Department of Chemistry &Biochemistry, University of Oregon, Eugene, Oregon 97403, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Lonergan
authors.affiliation: Department of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Pullerits
authors.affiliation: Oregon Center for Optics and Department of Chemistry &Biochemistry, University of Oregon, Eugene, Oregon 97403, USA.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Marcus