Structural, optical, surface topographical and electrical properties of transparent vanadium doped ZnO absorbing layer for photovoltaic application

In the present investigation, vanadium-doped zinc oxide (V: ZnO) thin films were synthesized by the sol-gel dip-coating technique by varying the percentage of V. Raman spectroscopy was used for structural conformation, showing the making of an impurity phase on increasing the V doping whereas, SEM analysis revealed that increasing the vanadium (V) concentration surface gets smoothen. The V incorporation into the ZnO crystal lattice was confirmed by the EDS analysis. The 3-D surface topography and stereometric analysis show the 3-D surface texture parameters that affect the optical and electrical features of the material. The results from experimental measurements suggest that V: ZnO thin films prepared at 3% V had the most suitable surface in terms of roughness, texture, and waviness. UV analysis showed a decrease in E_g value with an increase in the doping percentage, the optical parameters such as absorption and transmission (%) were also analyzed. The electrical properties were studied using I-V measurements from which resistivity for doped ZnO films was found to significantly decrease and increase its current densities. In photovoltaic characteristic evaluation, the efficiency (η) was attributed to variation in the value of J_sc. The C-3 coated PV cells had superior J_SC at 36.70 mA/cm², resulting an increased overall efficiency without changing the open-circuit voltage or fill factor. Thus, 3% doping concentration has a favourable influence on PV cell performance, indicating a possible path for improving energy conversion efficiencyby ~ 11.76% with better stability. This material can be proven as a good coating-absorbing layer for PV cells.