Akademik Veri Yönetim Sistemi
OPTICAL MATERIALS, cilt.175, 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.