Akademik Veri Yönetim Sistemi
OPTICAL MATERIALS, cilt.175, sa. 118048 , ss.1-11, 2026 (SCI-Expanded, Scopus)
In this study, Ge doping was gradually employed within the range of 0–30%, substituting Sn, combined with fixed 10% Mn doping substituting Zn, as a dual-cation doping strategy in kesterite Cu2ZnSnSe4 (CZTSe) solar cells. Cu/Sn/Zn/Cu/Mn/Ge precursor were deposited layer by layer onto Mo-coated glass substrates via DC/RF magnetron sputtering. Subsequently, a Se capping layer was deposited through thermal evaporation. The samples were then annealed in a Se vapor atmosphere using rapid thermal processing (RTP). The reacted films were characterized using a range of analytical techniques. Energy-dispersive X-ray spectroscopy confirmed the expected elemental ratios, indicating precise stoichiometric control. Structural analyses confirmed the kesterite CZTSe phase, regardless of doping level. X-ray diffraction (XRD) and Raman spectra exhibited shifts in peak positions correlated with the level of Ge doping, indicating successful substitution. While the Ge-free film displayed a bilayer morphology, 20% Ge doping promoted the formation of a compact, single-layer grain structure with a smoother surface, as revealed by scanning electron microscopy (SEM) images. However, increasing Ge doping beyond 20% led to the appearance of Mn- and Ge-free Cu-rich secondary phases, which were manifested as plate-like grain structures. The bandgaps determined from optical data varied between 1.06 and 1.13 eV, depending on the doping level. X-ray photoelectron spectroscopy (XPS) exhibited characteristic binding energies of Cu, Zn, Mn, Sn, Ge, and Se, suggesting the formation of the CZTSe structure. The J–V curves of the cells showed that the CZMnTSe-Ge20 (20% Ge doped) device exhibited the best performance, achieving an efficiency of 7.29% along with an open-circuit voltage (Voc) of 0.35 V, and fill factor (FF) of 0.69. In light of these findings, 20% Ge doping at a constant Mn ratio appears to offer the most favorable balance of the characteristics, identifying it as the optimal level for high-performance solar cells.