Abstract
Cu(2)ZnSnSe(4) is a promising light-absorbing material for cost-effective and eco-friendly thin-film solar cells; however, its synthesis often leads to secondary phases that limit device efficiency. To overcome these challenges, we devised a straightforward and efficient method to obtain single-phase Cu(2)ZnSnSe(4) nanocrystalline powders directly from the elements Cu, Zn, Sn, and Se via mechanochemical synthesis followed by vacuum annealing at 450 °C. Phase evolution monitored by X-ray diffraction (XRD) and Raman spectroscopy at two-hour milling intervals confirmed the formation of phase-pure kesterite Cu(2)ZnSnSe(4) and enabled tracking of transient secondary phases. Raman spectra revealed the characteristic A(1) vibrational modes of the kesterite structure, while XRD peaks and Rietveld refinement (χ(2) ~ 1) validated single-phase formation with crystallite sizes of 10-15 nm and dislocation densities of 3.00-3.20 10(15) lines/m(2). Optical analysis showed a direct bandgap of ~1.1 eV, and estimated linear and nonlinear optical constants validate its potential for photovoltaic applications. Scanning electron microscopy (SEM) analysis showed uniformly distributed particles 50-60 nm, and energy dispersive X-ray (EDS) analysis confirmed a near-stoichiometric Cu:Zn:Sn:Se ratio of 2:1:1:4. X-ray photoelectron spectroscopy (XPS) identified the expected oxidation states (Cu(+), Zn(2+), Sn(4+), and Se(2-)). Electrical characterization revealed p-type conductivity with a mobility (μ) of 2.09 cm(2)/Vs, sheet resistance (ρ) of 4.87 Ω cm, and carrier concentrations of 1.23 × 10(19) cm(-3). Galvanostatic charge-discharge testing (GCD) demonstrated an energy density of 2.872 Wh/kg(-1) and a power density of 1083 W kg(-1), highlighting the material's additional potential for energy storage applications.