Cu2ZnSnS4 monograin layer solar cells for flexible photovoltaic applications.

Monograin powder technology is one possible path to developing sustainable, lightweight, flexible, and semi-transparent solar cells, which might be ideal for integration with various building and product elements. In recent years, the main research focus of monograin technology has centered around understanding the synthesis and optoelectronic properties of kesterite-type absorber materials. Among these, Cu2ZnSnS4 (CZTS) stands out as a promising solar cell absorber due to its favorable optical and electrical characteristics. CZTS is particularly appealing as its constituent elements are abundant and non-toxic, and it currently holds the record for highest power conversion efficiency (PCE) among emerging inorganic thin-film PV candidates. Despite its advantages, kesterite solar cells' PCE still falls significantly behind the theoretical maximum efficiency due to the large VOC deficit. This review explores various strategies aimed at improving VOC losses to enhance the overall performance of CZTS monograin layer solar cells. It was found that low-temperature post-annealing of CZTS powders reduced Cu-Zn disordering, increasing Eg by ∼100 meV and VOC values; however, achieving the optimal balance between ordered and disordered regions in kesterite materials is crucial for enhancing photovoltaic device performance due to the coexistence of ordered and disordered phases. CZTS alloying with Ag and Cd suppressed non-radiative recombination and increased short-circuit current density. Optimizing Ag content at 1% reduced CuZn antisite defects, but higher Ag levels compensated for acceptor defects, leading to reduced carrier density and decreased solar cell performance. Co-doping with Li and K resulted in an increased bandgap (1.57 eV) and improved VOC, but further optimization is required due to a relatively large difference between measured and theoretical VOC. Heterojunction modifications led to the most effective PCE improvement in CZTS-based solar cells, achieving an overall efficiency of 12.06%.

Antimicrobial particles based on Cu2ZnSnS4 monograins.

In this research, Cu2ZnSnS4 (CZTS) particles were successfully fabricated via the molten salt approach from the copper, zinc and tin sulphides as raw precursors. SEM analysis revealed that CZTS particles are tetragonal-shaped with sharp edges, smooth flat plane morphology, and crystal size varying from 10.8 to 28.7 µm. The phase and crystalline structure of synthesized powders were investigated using XRD analysis, which confirms the presence of a tetragonal crystal structure kesterite phase. The chemical composition of CZTS particles was evaluated by EDX spectroscopy, which identified the nearly stoichiometric composition with an averaged formula of Cu1.88Zn1.04SnS3.97. The TG/DTA-MS and ICP-OES analysis showed the possible decomposition pathways and predicted their degradation rate in aqueous solutions. The CZTS particles possessed highly effective concentration and time-dependent antimicrobial properties against medically relevant bacteria and yeast strains. The CZTS particles (1 g L-1) exhibited over 95.7 ± 1.9% killing efficiency towards M. luteus. In contrast, higher dosages (3.5 and 5 g L-1) led to its complete inactivation and reduced the P. aeruginosa cell viability to 43.2 ± 3.2% and 4.1 ± 1.1%, respectively. Moreover, the CZTS particles (0.5 g L-1) are responsible for causing 54.8 ± 1.8% of C. krusei and 89.7 ± 2.1% of C. parapsilosis yeasts death within the 24 h of exposure, which expanded to almost 100% when yeasts were treated with two times higher CZTS concentration (1.0 g L-1). The mechanism of action has been proposed and evidenced by monitoring the 2',7'-dichlorofluorescein (DCF) fluorescence, which revealed that the overproduction of reactive oxygen species (ROS) is responsible for microorganism death.

Synthesis and physical characteristics of narrow bandgap chalcogenide SnZrSe 3.

Background: The development of organic/inorganic metal halide perovskites has seen unprecedent growth since their first recognition for applications in optoelectronic devices. However, their thermodynamic stability and toxicity remains a challenge considering wide-scale deployment in the future. This spurred an interest in search of perovskite-inspired materials which are expected to retain the advantageous material characteristics of halide perovskites, but with high thermodynamic stability and composed of earth-abundant and low toxicity elements. ABX 3 chalcogenides (A, B=metals, X=Se, S) have been identified as potential class of materials meeting the aforementioned criteria. Methods: In this work, we focus on studying tin zirconium selenide (SnZrSe 3) relevant physical properties with an aim to evaluate its prospects for application in optoelectronics. SnZrSe 3 powder and monocrystals were synthesized via solid state reaction in 600 - 800 °C temperature range. Crystalline structure was determined using single crystal and powder X-ray diffraction methods. The bandgap was estimated from diffused reflectance measurements on powder samples and electrical properties of crystals were analysed from temperature dependent I-V measurements. Results: We found that SnZrSe 3 crystals have a needle-like structure (space group - Pnma) with following unit cell parameters: a=9.5862(4) Å, b=3.84427(10) Å, c=14.3959(5) Å. The origin of the low symmetry crystalline structure was associated with stereochemical active electron lone pair of Sn cation. Estimated bandgap was around 1.15 eV which was higher than measured previously and predicted theoretically. Additionally, it was found that resistivity and conductivity type depended on the compound chemical composition. Conclusions: Absorption edge in the infrared region and bipolar dopability makes SnZrSe 3 an interesting material candidate for application in earth-abundant and non-toxic single/multi-junction solar cells or other infrared based optoelectronic devices.