title: Hot electron and hole dynamics in thiol-capped CdSe quantum dots revealed by 2D electronic spectroscopy.
abstract: Colloidal quantum dots (QDs) have attracted interest as materials for opto-electronic applications, wherein their efficient energy use requires the understanding of carrier relaxation. In QDs capped by bifunctional thiols, used to attach the QDs to a surface, the relaxation is complicated by carrier traps. Using 2D spectroscopy at 77 K, we follow excitations in thiol-capped CdSe QDs with state specificity and high time resolution. We unambiguously identify the lowest state as an optically allowed hole trap, and identify an electron trap with excited-state absorption. The presence of traps changes the initial dynamics entirely by offering a different relaxation channel. 2D electronic spectroscopy enables us to pinpoint correlations between states and to easily separate relaxation from different starting states. We observe the direct rapid trapping of 1S3/2, 2S3/2, and 1S1/2holes, and several competing electron relaxation processes from the 1Pestate.
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se.
authors.forename: Nils
authors.identifier: http://orcid.org/0000-0001-7563-9843
authors.initials: N
authors.lastname: Lenngren
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se and Department of Chemistry, Qena Faculty of Science, South Valley University, Qena 83523, Egypt.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Abdellah
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se and Gas Processing Center, College of Engineering, Qatar University, PO Box 2713, Doha, Qatar.
authors.forename: Kaibo
authors.initials: K
authors.lastname: Zheng
authors.affiliation: Gas Processing Center, College of Engineering, Qatar University, PO Box 2713, Doha, Qatar.
authors.forename: Mohammed J
authors.initials: MJ
authors.lastname: Al-Marri
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se.
authors.forename: Donatas
authors.initials: D
authors.lastname: Zigmantas
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se and Regional Centre for Special Optics and Optoelectronic Systems (TOPTEC), Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Za Slovankou 1782/3, 182 00 Prague 8, Czech Republic.
authors.forename: Karel
authors.initials: K
authors.lastname: Žídek
authors.affiliation: Department of Chemical Physics, Lund University, PO Box 124, 221 00 Lund, Sweden. tonu.pullerits@chemphys.lu.se.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Pullerits