Ultrafast Spectroscopy of Quantum Confined States in a Single CdSe Nanowire

Abstract

We measure for the first time transient absorption spectra of individual CdSe nanowires with about 10 nm diameter. Confinement of the carrier wave functions leads to discrete states which can be described by a six-band effective mass model. Combining transient absorption and luminescence spectroscopy allows us to track the excitation dynamics in the visible and near-infrared spectral range. About 10% of all absorbed photons lead to an excitation of the lowest energy state. Of these excitations, less than 1% lead to a photon in the optical far-field. Almost all emission is reabsorbed by other parts of the nanowire. These findings might explain the low overall quantum efficiency of CdSe nanowires.

Ultrathin inorganic molecular nanowire based on polyoxometalates

“…Nanowires, in which two dimensions of the materials are on a scale of tens of nanometres or less and the length of the remaining dimension can be increased without confinement, have been attracting attention because of their large surface area and quantum mechanical effects that result in unique material properties. Different compounds, such as metallic compounds 1 , semiconducting compounds 2 3 4 5 6 7 8 9 10 , metal oxides 11 12 13 and organic polymers 14 15 16 17 , can be grown to form nanowires for use in functional materials and devices that have been successfully applied as sensors 13 , transistors 2 5 , semiconductors 3 , photonics devices 7 11 and solar cells 4 6 .…”

Imaging nano-objects by linear and nonlinear optical absorption microscopies

“…The fast 7 ps decay in this trace is attributed to internal relaxation, and the slower nanosecond decay that appears as an offset in these experiments is assigned to energy transfer from the particle to its surroundings (in this case the glass substrate). TAM experiments can also be used to study charge carrier relaxation in semiconductor nanostructures, [21,45,46,55,83,97,109,110,134,137,145,146,164] and conducting polymers. [52,[171][172][173] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 between different nanostructures, and also about spatial variations within a single nanostructure.…”

Concerted single-nanowire absorption and emission spectroscopy: Explaining the origin of the size-dependent Stokes shift in single cadmium selenide nanowires

“…This is due to their distinctive size-and shape-dependent optical and electrical properties [1,2]. Recent advances in the synthesis of high quality one-dimensional (1D) II-VI nanostructures have led to extensive studies of their optoelectronic properties [3][4][5][6][7][8], as well as their use in diverse applications [9,10]. In this regard, the anisotropic shape of these materials allows for efficient charge transport, while quantum confinement leads to tunable electronic properties.…”