Iulian Boerasu

Herein, based on the reviewed literature, the current marketability challenges faced by kesterite CZTS based-solar cells is addressed. A knowledge update about the attempts to reduce the open circuit voltage deficit of kesterite CZTS solar cells will be addressed, with a focus on the impact of Cu/Zn order/disorder and of Se doping. This review also presents the strengths and weaknesses of the most commercially attractive synthesis methods for synthesizing thin kesterite CZTS films for photovoltaic applications.

In this work, we report the modification of commercially available electrochemical electrodes with tin oxide (SnO₂) and Pd doped SnO₂ (Pd-SnO₂) via pulsed laser-induced forward transfer (LIFT). The pulsed light irradiation working as in situ pulsed photo-thermal treatment allows for the transfer of SnO₂ and Pd-SnO₂ from UV absorbing metal complex precursors onto flexible, commercially available screen-printed electrodes. The laser transfer conditions are optimized and the material transferred under different conditions is evaluated morphologically and chemically, and its functionality is tested against the detection of copper ions. For example, by applying laser fluences in the range 100–250 mJ/cm², the shape and the size of the transferred features ranges from nano-polyhedrons to near corner-grown cubic Pd-SnO₂ or near cubic Pd-SnO₂. In addition, the EDX analysis is consistent with the XPS findings, i.e., following laser transfer, Pd amounts lower than 0.5% are present in the Pd-SnO₂ pixels. First sensing tests were carried out and the transferred Pd-SnO₂ proved to enhance the cathodic peak when exposed to Cu(II) ions. This photo-initiated fabrication technology opens a promising way for the low-cost and high-throughput manufacturing of metal oxides as well as for electrodes for heavy metal ion detection.

Results on studies of pure tungsten oxide WO₃ and 2, 3 and 4% Fe-doped WO₃ grown on the sapphire substrates by reactive pulsed laser deposition technique are reported. From X-ray diffraction it results that the crystalline structures changed with the substrate temperature and the peaks diffraction having a small shift by the amount of Fe content in WO₃ lattice was noticed. Scanning electron microscopy presented a random behavior of WO₃ nanocrystallites size with substrate temperatures. In the presence of 2% Fe-doped WO₃, the nanocrystallites size varied gradually from 60 nm to 190 nm as substrate temperature increased. The transmission spectra of the pure and 2, 3 and 4% Fe-doped WO₃ films were obtained within the 300–1200 nm spectral range. The refractive index of WO₃ and Fe-doped WO₃ layers were calculated by the Swanepoel method. The refractive index of pure WO₃ shows a variation from 2.35–1.90 and for 2% Fe-doped WO₃ from 2.30–2.00, as the substrate temperature increased. The contents of 3 and 4% Fe-doped WO₃ presented nearly identical values of the refractive index with pure and 2% Fe-doped WO₃, in error limits, at 600 °C. The optical band gap changes with substrate temperature from 3.2 eV to 2.9 eV for pure WO₃ and has a small variation with the Fe.