3.6.1 Small Angle X-ray Scattering
SAXS measurements for the kinetic study of perovskites were performed at the Deutsches Elektron-Synchrotron (DESY) in Hamburg, Germany. All experiments were carried out at the P03, Micro- and Nanofocus X-ray Scattering (MiNaXS) beamline at the PETRA III storage ring. For
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our setup, the sample was loaded in a quartz capillary and mounted in a holder in front of the SAXS vacuum tube which includes the SAXS detector. The setup for the SAXS detection is depictured in figure 11 where the sample-to-detector distance is variable.
Figure 11: Schematic representation of an experimental setup. The collimated X-ray beam hits the vertical sample. The scattered X-rays are detected by the SAXS detector in a vacuum tube which leads to the characteristic 2D scattering pattern. The sample-to-detector distance is responsible for the detected q-values of the scattered X-rays.
The sample-to-detector distance was set to be 1.66 m and 2.54 m, leading to a q-range from 0.01 nm-1 ≤ q ≤ 3.0 nm-1. The measurements were performed with a beam size of 320 nm x 250 nm and radiation of wavelength 0.0954 nm. The photon energy was 13 keV and the scattering data was collected with a Pilatus 1M detector. Silver behenate with a d-spacing of 58.38 Å was used as standard for the calibration. A quartz capillary (Ø=1 mm, Hildenberg GmbH) with wall thickness of 10 µm was used as the analysis cell. The 2 dimensional scattering patterns were acquired at an interval of 0.5 sec for 20 min. The background correction for the one dimensional SAXS profiles was made using toluene.
3.6.2 UV-Vis Absorbance Spectroscopy and Analysis
UV-Vis absorbance spectra were recorded on Agilent 8453 UV-Vis spectrophotometer. The instrument is equipped with a deuterium and tungsten light source covering the wavelength range of 190 nm to 1100 nm. The collimated beam passes the samples in the quartz cuvette and is dispersed onto a photodiode array detector. The UV-Visible ChemStation software was used for spectral analysis.
Time-dependent UV-Vis absorption spectra were recorded on a USB 2000+ XR1-ES detector (λ=200 nm to 1100 nm) equipped with a deuterium-halogen light source (DH-2000-BAL, Ocean Optics, Germany) and connected with fiber optic cables. A quartz capillary (Ø=1 mm, Hildenberg
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GmbH) with wall thickness of 10 µm was used as the analysis cell. Ocean View Software was used for the real-time acquisition and analysis. The acquisition time was set to 0.5 min for perovskite and CdS nanocluster growth.
3.6.3 Confocal Laser Scanning Microscopy
The Confocal Laser Scanning Microscope (CLSM) Leica TCS SP8, equipped with an inverse DMI 6000B Microscope (Leica) was used for fluorescence imaging of perovskites in the microfluidic chip EH09. The specimen was mounted on a precise x-, y-, z-stage. The emission (region of interest scan, ROI) along the microfluidic channel was recorded within the wavelength region 415 nm to 780 nm and a laser excitation of λexc = 405 nm. The high-precision syringe pump (NEMESYS, Cetoni GmbH) guarantees laminar flows within the EH09 microfluidic chip. The inlets and outlets of the microfluidic device were connected via PE tubings (Scientific Commodities Inc.) and PE luer locks (Braun Melsungen AG) to gas-tight syringes (Hamilton Company).
3.6.4 Transmission Electron Microscopy
The colloidal samples were analyzed with three different Transmission Electron Microscopes (TEM). TEM images were obtained by a Zeiss CEM 902 electron microscope (Zeiss Microscopy GmbH). The TEM was equipped with a tungsten cathode and the acceleration voltage was 80 kV.
For data imaging, the Gatan CCD Camera (Orius) with GMX 2.3 was used. Furthermore, the Zeiss LEO EM 922 Omega TEM with LaB6 cathode operating at 200 keV in combination with the Gatan CCD Camera (Ultrascan 1000) with GMS 1.9 was used. The high resolution Tecnai F20 instrument, running at 200 kV equipped with STEM and EDS detectors was used.
3.6.5 Scanning Electron Microscope
Scanning Electron Microscope (SEM) images were taken at the Zeiss Leo 1530 high resolution FE-SEM with Schottky Field Emission Gun (FEG) as the electron source, with high efficiency SE inlens and SE detector (Everhardt Thornley) for secondary electron images and the MiniCL cathodoluminescence detector (Oxford Instruments) for cathodoluminescence images. The operating voltage was set to 5 keV and the working distance was 7.4 mm.
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The high resolution Zeiss Ultra plus field emission was equipped with Schottky Field Emission electron source (FEG), SE inlens and SE detector (Everhardt Thornley) with acceleration voltage of 3.00 keV and a working distance from 3.5 nm to 3.8 mm.
3.6.6 Atomic Force Microscopy
Topographical and phase measurements were performed on the commercial Dimension 3100 Atomic Force Microscope (AFM, Veeco Instruments Inc., USA) equipped with a NanoScope V SPM controller and a hybrid XYZ closed-loop scanner (Bruker). Scanning of surface features was acquired in tapping mode under ambient conditions using aluminium-coated cantilevers (OTESPA-R3, Bruker). Image processing and data analysis were conducted with the Software Nanoscope Analysis v1.40 (Bruker).
3.6.7 Fluorescence Microscopy
The Olympus IX71 inverted microscope includes a light source (100 W mercury burner, U-LH100HG, Olympus), the Olympus microscope objective LCACHN 40x/0.55 Ph2 and the IX2-RFAC fluorescence filter cube with orange filter U-MWIGA3 (ET CY3, Olympus). The excitation light was passed through a band pass filter BP 530-550 nm, a dichroic mirror DM 570 nm and long pass emission filter BA 575-625 nm ensured only yellow-orange emission was detected. The Olympus U-CMAD3 model was used as microscope camera.
3.6.8 Fluorescence Spectroscopy
Fluorescence emission measurements were made on diluted solutions in quartz cuvettes (pathlength: 1 cm) on a Horiba Jobin Yvon Fluorolog-3 spectrometer. The PMT detector was corrected or wavelength dependent response and using the in-built correction function provided by Horiba Jobin Yvon.
Furthermore, the spectrofluorometer FP-6500 (Jasco Deutschland GmbH) with 150 W Xenon lamp was used to detect the wavelength reaching from 200 nm to 900 nm. Spectroscopy Software Spectra Manager was used for evaluating the measurements.
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3.6.9 X-ray Diffraction
The X'Pert MPD Pro (PANalytical, Almeo, Netherland) X-ray diffractometer was used to obtain diffraction data. As an X-ray source a Cu-Kα anode was used. The reaction chamber for studies of solids and gas reactions up to 900 °C and 10 bar was the XRK-900 (Anton Paar GmbH, Graz, Austria) for in-situ X-ray diffraction measurements.
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References
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[3] F. Ciesielczyk, P. Bartczak, and T. Jesionowski, ‘Removal of cadmium(II) and lead(II) ions from model aqueous solutions using sol–gel-derived inorganic oxide adsorbent’, Adsorption, vol. 22, no. 4–6, pp. 445–458, 2016.
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[7] S. Gonzalez-Carrero, R. E. Galian, and J. Pérez-Prieto, ‘Maximizing the emissive properties of CH 3 NH 3 PbBr 3 perovskite nanoparticles’, J. Mater. Chem. A, vol. 3, no. 17, pp. 9187–
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[8] G. Merck KGaA, Darmstadt, 2018.
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[9] D. Li et al., ‘Efficient synthesis of functional long-chain alkyl disulfides under liquid-liquid phase-transfer catalysis: The analysis of chemical equilibrium and phase-transfer mechanism’, Catalysis Communications, vol. 89, pp. 9–13, 2017.
[10] Kevin M. Walsh, University of Louisville Standard Operating Procedures, 2013, Retrieved from http;//mitghmr,spd.Louisville.edu/lutz/resources/sops/
In-situ Growth of CdTe Quantum Dots on Hectorite Nanoclays in Aqueous Medium
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