Ing. Markéta Šlapal Bařinková

The current strategies in the development of Sb2Se3 thin film solar cells involve fabrication and optimization of superstrate and substrate device architectures, with the preferable choice for TiO2 and CdS heterojunction layers. For CdS-based superstrate cells, several studies reported the necessity to apply CdCl2 or other metal halide-based post-deposition treatment (PDT), highlighting improvement of CdS/Sb2Se3 device efficiency. However, the need, effect, and mechanism of such PDT are very often not described. Additionally, the fact that many groups have not succeeded in demonstrating its benefits suggests that this strategy is not straightforward, requiring a deeper understanding towards a more unified concept. The present study proposes an alternative approach to the challenging CdCl2 PDT of CdS in CdS/Sb2Se3 device, involving controllable Cl incorporation in CdS films by systematically varying the concentration of NH4Cl in the CBD precursor solution from 1 to 8 mM. Structural and electrical characterizations are correlated with advanced measurements of Scanning Kelvin Probe, surface photovoltage, and atomic force microscopy to understand the impact of Cl incorporation on the properties of CdS films and CdS/Sb2Se3 devices. The validity of Cl incorporation in the CdS lattice and interdiffusion processes at the CdS-Sb2Se3 interface is confirmed by secondary ion mass spectrometry analysis. It is demonstrated that incorporation of 1 mM of NH4Cl, as a Cl source in CBD CdS, can boost the PCE of CdS/Sb2Se3 by ∼20 %. With this approach, we offer new perspectives on the optimization methodology for Cl-based CdS/Sb2Se3 device processing and complementary understanding of the physiochemistry behind these processes.

Photoactive nanoparticles have recently gained a lot of attention as alternative antimicrobial agents since their antimicrobial properties can be enhanced by illumination. The stable and reproducible application of these conditions is crucial in order to assess the antimicrobial effect of nanoparticles, illumination and the combination of these conditions on cells. Furthermore, the reproducibility of cell growth data is also essential to avoid measurement variability influencing statistical analysis. In this work we designed custom 3D-printed laboratory accessory for a bioreactor that ensured stable illumination of cell suspensions and enabled reproducible growth curves under the same growth conditions. The reproducibility of measurements was tested on Escherichia coli bacteria grown under illumination, with the addition of commercial ZnO nanoparticles, and with the combination of both factors. All tests showed a notable improvement in the reproducibility of bacterial growth curves and standard deviation of the measured data reduced below the documented instrument precision.

The impedance spectroscopy method (AC f = 4–8 MHz at a constant amplitude of 1 V) and Pt-IDE sensors were used to detect and monitor different concentrations (103, 106, and 109 CFU/mL) of both live and dead bacteria cells (Escherichia coli and Staphylococcus aureus). The analysis of the impedance spectra shows the differences in resistance with increasing concentrations for both types of bacteria and the presence of characteristic changes in the frequency range 10–100 kHz. The presence of live bacteria led to a decrease in the impedance value compared to dead cells, and the value of Rs + Rct decreased about two times. © 2023 by the authors. Licensee MDPI, Basel, Switzerland.