Supporting Information

Transcription

1 Supporting Information A Tellurium Precursor for Nanocrystal Synthesis: Tris(dimethylamino)phosphine Telluride Haochen Sun, Fudong Wang, and William E. Buhro* Department of Chemistry and Institute for Materials Science and Engineering, Washington University, Saint Louis, Missouri Table of Contents: Figure S1. Size-distributions histograms for CdTe quantum platelets S2 Figure S2. TEM images of CdTe quantum platelets after 2 h of reaction...s3 Figure S3. TEM images of CdTe quantum platelets using single-amine solvents..s4 Figure S4. Peak fitting for the absorption spectrum of CdTe quantum wires.s5 Figure S5. Diameter-distribution histogram of CdTe quantum wires. S6 Figure S6. 13 C{ 1 H} and 1 H NMR spectra of the evolved gas from the CdTe quantum-platelet synthesis....s7 Figure S7. 31 P{ 1 H} NMR spectrum from the reaction of (Me2N)3P and oleylamine S8 Figure S8. 31 P{ 1 H} NMR spectrum of the (Me2N)3P/(Me2N)3PTe mixture S9 Figure S9. 31 P{ 1 H} NMR spectrum of a CdTe quantum-platelet reaction mixture after 10 min of reaction...s10 Figure S10. High-resolution TEM image and electron diffraction pattern of CdTe quantum platelets. S11 Figure S11. Full-range XRD pattern of CdTe quantum platelets...s12 Figure S12. Photoluminescence and photoluminescence excitation spectra of CdTe quantum platelets S13 Figure S13. Photoluminescence spectra of (CdTe)13 nanoclusters and CdTe quantum wires. S14 S1

2 Figure S1. Size-distributions histograms for the dimensions of CdTe quantum platelets measured from TEM images (like those in Figure 2a, b, and c). (a) Length: mean value was determined to be 58.8 ± 6.1 nm; (b) Width: mean value was determined to be 25.0 ± 3.4 nm; and (c) Thickness: mean value was determined to be 1.91 ± 0.13 nm. S2

3 Figure S2. TEM image of CdTe quantum platelets after an insufficient reaction time of 2 h. S3

4 Figure S3. TEM images of CdTe quantum platelets, using (a) oleylamine and (b) n-octylamine as sole solvents. S4

5 Figure S4. Gaussian peak fitting for the absorption spectrum of CdTe quantum wires. The black line is the multi-point baseline-substracted absorption spectrum of CdTe quantum wires. Five absorption features at wavelengths of 735 nm, 712 nm, 670 nm, 605 nm, and 539 nm were determined, which are represented in green curves. The red curve is the sum of the fitted peaks, which fits well with the spectrum. S5

6 Figure S5. Size-distributions histogram for the diameter of CdTe quantum wires measured from TEM images (like those in Figure 6). The mean diameter was determined to be 6.8 ± 0.4 nm. S6

7 Figure S6. Room temperature (a) 13 C{ 1 H} and (b) 1 H NMR spectra of the evolved gas collected by bubbling through CDCl3 from a typical CdTe quantum-platelet synthesis. S7

8 Figure S7. Room-temperature 31 P{ 1 H} NMR spectrum from the reaction of (Me2N)3P and oleylamine (conducted at 100 C). (a-c) After 1 h of reaction. (a) Resonances in the range of 2 30 ppm; (b) Resonances in the range of ppm; and (c) Full spectrum. (d) After 8 h of reaction, with the inset showing the expand spectrum in the range of 0 30 ppm. S8

9 Figure S8. Room-temperature 31 P{ 1 H} NMR spectrum of the (Me2N)3P/(Me2N)3PTe mixture showing two major resonances at 115 and 58 ppm. S9

10 Figure S9. Room-temperature 31 P{ 1 H} NMR spectrum of CdTe quantumplatelet reaction mixture after 10 min at 100 C, with inset (a) showing expanded spectrum in the range of ppm and inset (b) showing expanded spectrum in the range of 0 30 ppm. S10

11 Figure S10. High-resolution TEM image of a CdTe quantum platelet with the inset showing the electron-diffraction pattern of many CdTe quantum platelets. The platelets are extremely susceptible to beam damage, precluding collection of high-quality lattice images of a single platelet. Minor parts of the lattice images exhibit the zinc-blende structure, rather than the pure wurtzite phase shown from the XRD pattern. Both phases are marked with colors (blue for wurtzite, orange for zinc blende) in the image. The observation of the zinc-blende phase in the high-resolution image is ascribed to electron-beam damage. The wurtzite phase shows a d spacing of nm, close to the value of nm determined from the XRD pattern for the 002 spacing. The zinc-blende phase shows a d spacing of nm, corresponding to the 111 spacing in bulk CdTe (0.374 nm). S11

12 Figure S11. XRD pattern of CdTe quantum platelets over the extended 2θ range of S12

13 Figure S12. Photoluminescence (blue), photoluminescence excitation (black), and absorption (red) spectra of CdTe quantum platelets. The photoluminescence spectrum was obtained with excitation at 370 nm. Emission peaks at 500 nm and 575 nm are found in the spectrum. The photoluminescence excitation spectrum collected at a fixed emission wavelength of 575 nm does not match the absorption spectrum. Instead, it shows two valleys whose positions match those of the absorption peaks. The results indicate that the observed weak emission is not due to the CdTe quantum platelets, but rather from other trace emitters (perhaps quantum dots) present in the sample. Since the CdTe quantum platelets are strong absorbers, photons are absorbed by the platelets instead of entering the detector, resulting in the valleys shown in the photolumescence excitation spectrum. S13

14 Figure 13. Photoluminescence spectra (red lines) of (a) (CdTe)13 nanoclusters and (b) CdTe quantum wires. The black lines are the corresponding absorption spectra. S14