Characterizations of extrinsically doped CZTS thin films for solar cell absorbers fabricated by sol-gel spin coating method

• DOI: 10.1016/j.apsadv.2022.100352
• Publication Date: 2022-12-07T04:28:35Z
• Authors: Ashoke Kumar Sen ...; Syed Farid Uddin ...; Md. Shehan Habib; Mohammad Robiul H...; Khalid Hossain; Nipu Kumar Das; Muhammad Quamruzz...; M.A. Matin; N. Amin
• Keywords: Spin Coating; Chemical bath deposition; Passivation

In copper zinc tin sulfide (CZTS) based thin films, antisite (CuZn) represents the major p-type acceptor defect with low formation energy. This can create defect-dominated carrier recombination hotspots, which reduces power conversion efficiency. Extrinsic doping in cationic sites of CZTS film during synthesis is an effective way to passivate this defect. It has previously been reported that employing Cd as a dopant and improve quality. Injecting toxic into non-toxic may more problems than it solves. Simultaneous other atoms like Mg hypothesized accomplish goal lowering concentration. For this, important know effect separately under analogous experimental conditions. The structural, morphological, optical properties, well chemical bonding states, sol-gel spin-coated films were investigated study using independent controlled doping. fabrication procedure consisted two steps: spin coating followed by sulfurization. As solvent for precursors creating sols processes, dimethyl sulfoxide (DMSO) was employed. Each dopant's precursor concentration chosen ensure identical mole percentage solution. fabricated characterized undoped doped forms X-ray diffractometry (XRD) Rietveld refinements, Raman spectroscopy, Field emission scanning electron microscopy (FESEM), 3D profilometry, Ultraviolet-visible near-infrared (UV-Vis NIR) spectroscopy. elemental composition ratio states probed Energy dispersive spectroscopy (EDS) photoelectron (XPS), respectively. Fabricated exhibit distinct synergistic features depending on types used process. crystal structure absorber valence elements (Cu, Zn, Sn, S) not changed shown XRD, Raman, XPS analyses. main diffraction peak at (112) plane found Bragg's angle 28.6° sample. shifts left upon 28.2° 28.4° owing different ionic radii dopants relative Zn ions, indicates presence films. probes Cu-Sn-S secondary phases: cubic Cu2SnS3 305 cm−1 sample, tetragonal 296 Cd-doped orthorhombic Cu3SnS4 291 Mg-doped From EDS results, appears 45% both samples are partially substituted Mg, band gap decreases from 1.61 eV 1.56 when compared samples. samples, shrinks even 1.1 eV. corresponds shifting absorbance spectra higher wavelengths known "redshift". Urbach energy determined be 284 meV 1072 respectively, address tailing issues. enhances crystallite size slightly while decreasing microstrain dislocation density. RMS surface roughness 147 nm 280 nm, Nevertheless, primary peaks Cu, S, Cd, O, lines these elements, all present identified These results imply Zn-cationic site virgin regulated systematically get appreciated solar cell absorber.