Chemical Synthesis, Doping, and Transformation of. Magic-Sized Semiconductor Alloy Nanoclusters

Transcription

1 Supporting Information Chemical Synthesis, Doping, and Transformation of Magic-Sized Semiconductor Alloy Nanoclusters Jiwoong Yang,,,# Franziska Muckel,,# Woonhyuk Baek,, Rachel Fainblat,,, Hogeun Chang,, Gerd Bacher,, * and Taeghwan Hyeon,, * Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea. School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea. Werkstoffe der Elektrotechnik und CENIDE, University Duisburg-Essen, Bismarckstraße 81, Duisburg, Germany. # J. Yang and F. Muckel contributed equally to this work. * thyeon@snu.ac.kr (T.H.); gerd.bacher@uni-due.de (G.B.) S1

2 Figure S1. LDI-MS spectrum of undoped ZnSe clusters. (a) LDI-TOF MS spectrum of undoped ZnSe clusters ionized by chlorine anions. (b) The expansion around the main peak of panel (a) (violet rectangle) in isotopic resolution. The calculated isotopic distribution (blue line) is shown for comparison to the experimental data (black line) of (ZnSe)13. Peaks from the other ZnSe clusters, such as (ZnSe)34 or (ZnSe)19, are not observed, demonstrating the high purity of the (ZnSe)13 clusters. Minor peaks are caused by fragmentation. Figure S2. Temperature-dependent absorption spectra of the alloy clusters. Temperaturedependent absorption spectra of the alloy clusters with overall compositions of (a) ZnSe, (b) Zn0.8Cd0.2Se, (c) Zn0.6Cd0.4Se, (d) Zn0.4Cd0.6Se, and (e) Zn0.2Cd0.8Se. All samples exhibit a redshift with increasing temperature, which shows that the clusters exhibit semiconductor-like band structures despite their extremely small sizes. S2

3 Figure S3. LDI-MS spectrum of the reaction intermediates during the synthesis of the alloy clusters. The data is acquired from the reaction mixture after 1 min of the reaction. Peaks corresponding to (CdSe)34 were clearly observed instead of alloy clusters of (ZnyCd1-ySe)34. Figure S4. Optical properties of the undoped ZnSe clusters. Room-temperature absorption (red) and photoluminescence (blue) spectra of undoped ZnSe clusters. The absorption spectrum matches with the previous report on (ZnSe)13 clusters. S1 PL spectrum shows weak band-edge emission of the undoped ZnSe clusters that is influenced by the surface defect transitions (QY < 0.1%). S3

4 Figure S5. MCD zero crossings of the Mn 2+ -doped alloy clusters. The energetic positions of the first zero crossings in MCD are shown according to the composition of the alloy clusters. S4

5 Figure S6. Simulation of MCD spectra. (a) Probabilities of each species ZnxCd13-xSe13 containing between 0 (pure (CdSe)13) and 13 Zn atoms (pure (ZnSe)13) for a different overall Zn content of 0%, 20%, 40%, 60%, 80%, and 100% based on a binomial distribution. (b) Simulated MCD spectra of selected species. Experimental data for pure Mn 2+ -doped (ZnSe)13 are shown for comparison. S5

6 Figure S7. Temperature-dependent MCD spectra. Temperature-dependent MCD spectra of (a) Mn 2+ -doped Zn0.6Cd0.4Se alloy clusters (xmn = 6%) and (b) Mn 2+ -doped (ZnSe)13 clusters (xmn = 6%) at B = 1.63 T. Room temperature spectra are shown in the insets. S6

7 Figure S8. TEM elemental analysis of Mn 2+ -doped Cd 0.8 Zn 0.2 Se alloy quantum nanoribbons (x Mn = 6%). EDS mapping images are measured at Cd L (green), Se K (blue), Zn K (red), and Mn K edge (yellow) and their merged image. S7

8 Figure S9. TEM elemental analysis of Mn 2+ -doped Cd 0.6 Zn 0.4 Se alloy quantum nanoribbons (x Mn = 6%). EDS mapping images are measured at Cd L (green), Se K (blue), Zn K (red), and Mn K edge (yellow) and their merged image. S8

9 Figure S10. EDS Spectra of the alloy nanoribbons. EDS spectra of the sample corresponding to (a) Figure S8 and (b) Figure S9. S9

10 Figure S11. Analysis on the lattice parameters of the nanoribbons acquired from synchrotron HRPD. Lattice parameters, (a) a and (b) c of the wurtzite-nanoribbons, were acquired from HRPD data (Figure 5e). For comparison, calculated lattice parameters of alloy nanoribbons (red dashed line) were acquired by Vegard s law based on the lattice parameters of wurtzite-cdse nanoribbons (blue dashed line from our experiment) and those of wurzite- ZnSe nanoplates with the same number of atomic layers in the thickness direction (green dashed line from the literature S1 ). Figure S12. TEM images of alloy nanorods obtained from the alloy clusters. TEM images of (a) Cd0.8Zn0.2Se, (b) Cd0.6Zn0.4Se, (c) Cd0.4Zn0.6Se, and (d) Cd0.2Zn0.8Se alloy nanorods. S10

11 Figure S13. Experimental setup for in-situ small-angle X-ray scattering. (a) Overall setup for in-situ measurement. (b) A photograph showing reactor system (red rectangle parts of panel (a)) used for in-situ study. (c) A photograph showing the sample stage (blue rectangle parts of panel (a)) for SAXS measurement. S11

12 Figure S14. Small-angle X-ray scattering data for assemblies of the n-octylamine passivated alloy clusters in n-octylamine. Regardless of the composition, assemblies of the n-octylamine passivated alloy clusters exhibit 2D lamellar self-assembled structures. Table S1. Summary of the photoluminescence quantum yields for Mn 2+ emission in the Mn 2+ -doped alloy clusters. Zn:Cd composition 1.0:0 0.8:0.2 Samples Quantum Yield xmn (%) (%) : : : S12

13 Table S2. Lattice constants of alloy nanoribbons acquired from HRPD and calculation. Lattice parameters of bulk hexagonal CdSe are also provided for comparison (JCPDS card # ). Zn:Cd composition a (Å) c (Å) 0: Experimental 0.2: : Calculated 0.2: from Vegard s law a 0.4: Bulk hexagonal CdSe a Calculated lattice parameters of alloy nanoribbons were acquired by Vegard s law based on the lattice parameters of wurtzite-cdse nanoribbons (our experimental value) and those of wurzite-znse nanoplates with the same number of atomic layers in the thickness direction (a = 3.88 Å and c = 6.45 Å from the literature S1 ). References for the Supporting Information S1. Wang, Y.; Zhou, Y.; Zhang, Y.; Buhro, W. E. Inorg. Chem. 2015, 54, S13