Crystallography and Structure Refinement

The data of complex (1) were collected at 150(2)K on a Bruker-Nonius Apex II CCD diffractometer using MoKα radiation (α = 0.71073Å) and were corrected for Lorentz-polarisation effects and absorption (SADABS) (Krause, Herbst-Irmer, Sheldrick, &

Stalke, 2015). The structure was solved by dual space methods (SHELXT) (Sheldrick, 2015) and refined on F² using all the reflections (SHELXL-2014) (Sheldrick, 2015). The central section, comprising most of the molecule is disordered and was modelled with 50% occupancy of two positions related by a center of symmetry (reduction of the space group symmetry did not reduce the disorder). The data for complex (2) collected on a Agilent Supernova diffractometer equipped with a MoK Microfocus X-ray source ( = 0.71073 Å). The Agilent CrysAlisPro software was used for data collection, cell refinement, data reduction and absorption collections. Molecular graphics were drawn by using the XSEED and Mercury software were collected at 150(2)K on a Bruker Apex II CCD diffractometer using MoKα radiation (λ = 0.71073Å). The structure was solved

by direct methods (SIR-2004) and refined on F² using all the reflections (SHELX) (Sheldrick, 2015). All the non-hydrogen atoms were refined using anisotropic atomic displacement parameters and hydrogen atoms were inserted at calculated positions using a riding model.

Diffraction data for the crystal (3) were collected on an Agilent SuperNova Dual diffractometer with an Atlas detector (graphite-monochromatized Mo-Kα radiation, λ = 0.71073 Å) at 100(2) K. The data were processed using CrysAlisPro, Agilent Technologies, Version 1.171.37.34 (release 22-05-2014 CrysAlis171.NET) and empirical absorption correction using spherical harmonics implemented in SCALE3 ABSPACK scaling algorithm. The structure was solved using the program SHELXT and was refined by the full matrix least-squares method on F² with SHELXL-2014/7 (Sheldrick, 2008).

All the non-hydrogen atoms were refined anisotropically. All the hydrogen atoms were placed at calculated positions and were treated as riding on their parent atoms. The structure exhibits a whole molecule disorder with the two components being related by a pseudo-inversion center. The occupancy of the main component refined to 0.640(2). The structure was also refined as a racemic twin with the twin parameter of 0.46(4). Drawing of the molecule was produced with Mercury (Macrae et al., 2006). Crystal data:

C44H56Co2F24O29Ti4, Mr = 1814.34, pink block, 0.49 × 0.28 × 0.26 mm³, orthorhombic, Pca21, a = 19.2672(4), b = 20.5759(5), c = 17.2453(4) Å, V = 6836.7(3) ų, Z = 4, Dc = 1.763 Mg/m³, 135126 measured reflections, 19480 unique reflections (Rint = 0.0517), 14499 observed reflections [(I > 2σ(I)], final R indices [(I > 2σ(I)]: R1 = 0.0858, wR2 = 0.2091. CCDC No. 1453304.

Diffraction data for the crystal (4) were collected on an Agilent SuperNova Dual diffractometer with an Atlas detector (graphite-monochromatized Mo-Kα radiation, λ = 0.71073 Å) at 100(2) K. The data were processed using CrysAlisPro, Agilent

Technologies, Version 1.171.37.34 (release 22-05-2014 CrysAlis171.NET) and empirical absorption correction using spherical harmonics implemented in SCALE3 ABSPACK scaling algorithm. The structure was solved using the program SHELXT and was refined by the full matrix least-squares method on F² with SHELXL-2014/7.The data of crystal (5) were collected at 150(2)K on a Bruker-Nonius Apex II CCD diffractometer using MoKα radiation ( = 0.71073Å) and were corrected for Lorentz-polarisation effects and absorption (SADABS) (Krause, Herbst-Irmer, Sheldrick, & Stalke, 2015). The structure was solved by dual space methods (SHELXT) (Sheldrick, 2015) and refined on F² using all the reflections (SHELXL-2014) (Sheldrick, 2015).

3.4 Thin Film Deposition Techniques

The semiconducting solid solution and composite thin films were developed by using the precursor (1-5). The thin films of precursor (1-4) were tailored on commercially available FTO-coated glass substrates using a self-designed AACVD assembly. Precursor (5) and metal acetates of (Mn, Fe, Cu, Ni, Zn, Cd and Pb) were fabricated on FTO substrate by an in house built EFDAACVD method. CuPbI3 films were deposited by EDP technique.

The general procedure of all these methods are described below:

3.4.1 Aerosol Assisted Chemical Vapor Deposition

The FTO-coated glass substrates purchased from Sigma Aldrich were cut to the dimension of 25.4 x 12.7 x 2.2 mm (L x W x D) and then prepared by ultrasonically washing with distilled water, acetone and then ethyl alcohol. Finally, they were washed with distilled water, kept in ethanol and dried in air before use. Substrate slides of the dimension of 25.2 mm × 12.7 mm were placed inside a tube furnace chamber and then heated up to the deposition temperature for 10 min before carrying out the deposition.

The aerosol of the precursor solution was formed by keeping the round-bottom flask in a

water bath above the piezoelectric modulator of an ultrasonic humidifier. The aerosol particles generated by the complexes were transferred into the hot wall region of the reactor by the carrier gas, whose flow rate was measured by a LIX linear flow meter and adjusted at 120 mL/min (Figure 3.1). In the last step of deposition, the aerosol assembly was turned off and a carrier gas was streamed over the substrates till the chamber cools down to normal temperature before they were removed for analysis.

Figure 3.1: Schematic diagram of Aerosol-Assisted Chemical Vapour Deposition.

3.4.2 Electric Field Directed Aerosol Assisted Chemical Vapor Deposition

The deposition of thin films on the commercially available fluorine-doped tin oxide (FTO) substrate dimension of 25.2 mm × 12.7 mm were carried out using an in-house built EFDAACVD technique as shown in Figure 3.2. Prior to the deposition, the FTO substrates were cleaned ultrasonically by washing with distilled water, acetone and ethyl alcohol. Finally, they were washed with distilled water, stored in ethanol and dried in air before use. The aerosol of the metal precursor was generated by keeping the reaction mixture in a two necked round bottom flask in a water bath above the piezoelectric modulator of an ultrasonic humidifier. The generated aerosol droplets of the precursor were transferred through an injection needle anode that was connected to a power supply.

The distance between the edge of the needle (anode) and the substrate was kept at 6 inches

and the substrate connected to the cathode was placed on the heater. Argon gas was passed through the aerosol mist at a flow rate of 200 mL/min to carry the aerosol droplets.

Figure 3.2: An in-house built experimental set up the orientation of the spray-needle was directed horizontally orthogonal to the plane of the substrate for Electric

Field-Directed Aerosol-Assisted Chemical Vapour Deposition.

A potential of 9.5 kV was applied across the terminals while the aerosol was flowing through the needle and the deposition were conducted at 400 ^°C for 45 min. The power supply and the ultrasonic humidifier were switched off and the aerosol line was closed.

The substrate was then coolled down to room temperature before it was removed from the heating plate to obtain thin films. As the coated area and the deposition rate are strongly dependent on the angle of the needle tip to the substrate, the aerosol spray-needle must be mounted in a horizontal position and perpendicular to the substrate surface at a suitable distance. It was observed that a relatively shorter distance between needle and substrate reduces the spinning time of the aerosol to yield a higher deposition rate and small coated areas having irregular particle shape. The increase in voltage and adjustment of distance between the needle tip and the substrate resulted in an evenly distributed thin film of precursor particles.

3.4.3 Electrophoretic Deposition

CuPbI3 modified FTO electrodes were prepared by adopting EPD technique as reported in the literature (Tajabadi et al., 2015) (Figure 3.3). In a typical experiment a two milligrams of the as-synthesized CuPbI3 powder was dispersed in 40 mL of 0.025 M Mg(NO3)2 in isopropanol.

Figure 3.3: Schematic diagram of electrophoretic deposition of charged particles on the anode of an EPD cell with planar electrodes.

The mixture was sonicated for 30 min to obtain a homogeneous suspension containing 0.05 mgL^-1 of CuPbI3. The pH of the suspension was adjusted at 3 by utilizing 1 M HCl solution before carrying out EPD experiment. The FTO glass substrates with an area of 10 mm × 20 mm were immersed in a 5% HF solution for a few minutes to remove the native oxide layer followed by washing in acetone and distilled water prior to being vertically immersed into the suspension. The linear distance between the electrodes was maintained at 10 mm and the DC potential and deposition time were adjusted to 80 V and 5 min, respectively. The coated film was dried at 50 °C in a vacuum oven to remove the excess solvent from the EPD process.