The earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (V_oc) and short circuit current density (J_sc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

Recently, the installation of photovoltaic modules in urban areas has been increasing. In particular, the demand for solar modules installed in a limited space is increasing. However, since the crystalline silicon solar module's size is proportional to the solar cell's size, it is difficult to manufacture a module that can be installed in a limited area. In this study, we fabricated a solar module with a shingled design that can control horizontal and vertical width using a bi-directional laser scribing method. We fabricated a string cell with a width of 1/5 compared to the existing shingled design string cells using a bi-directional laser scribing method, and we fabricated a solar module by connecting three strings in parallel. Finally, we achieved a conversion power of 5.521 W at a 103 mm × 320 mm area.

As we strive to mitigate the environmental impact caused by the use of fossil fuels, the exploration of alternative energy sources has gained significant attention. Solar energy, in particular, has emerged as a promising solution due to its eco-friendly nature and virtually limitless availability. Among the various types of solar cells that harness this abundant energy source, organic solar cells have garnered considerable interest. Organic solar cells feature a photo-active layer composed of organic semiconductors, offering a range of appealing advantages such as cost-effectiveness, flexibility, translucency, and the ability to produce customizable colors. However, the commercialization of organic solar cells has been impeded by certain challenges, notably their relatively low efficiency and stability. To overcome these obstacles and pave the way for wider adoption, researchers have been exploring innovative approaches, including the implementation of ternary blend organic solar cells. This strategy involves introducing a third component into the photo-active layer alongside the organic semiconductors, with the aim of enhancing the overall performance of the solar cell. In this paper, we delve into the issues associated with organic solar cells and focus on one potential solution: ternary blend organic solar cells. Specifically, we examine the application of this approach to PM6:Y6, which stands as one of the most popular combinations of organic semiconductors. By investigating the potential of ternary blends, particularly utilizing PM6:Y6, we aim to accelerate the commercialization of organic solar cells.

As the demand for the Internet of Things grows, research into indoor photovoltaics for wireless power is becoming important. In particular, perovskite has attracted considerable attention due to its superior performance compared to other candidates. However, various surface defects present in perovskite are a limiting factor for high performance. In particular, deep-level surface defects caused by uncoordinated Pb²⁺ ions directly limit charge transport. In low light environments, this appears to be a more significant hurdle. In this study, ethylenediamine, which can provide covalent bonding to uncoordinated Pb²⁺ ions through nitrogen, was used as a surface treatment material for indoor photovoltaics. X-ray photoelectron spectroscopy confirmed that the uncoordinated Pb²⁺ ions were effectively passivated by the terminal nitrogen of ethylenediamine. As a consequence, a V_OC of 0.998 V, a JSC of 0.139 mA cm^-2 and a fill factor of 83.03% were achieved, resulting in an indoor photoelectric conversion efficiency of 38.02%.

Sn-Pb narrow-bandgap perovskite solar cells, which is a light-harvesting layer thicker than 1.3 micrometers, is needed to enhance the low photocurrent. The fabrication of such a thick film through solution processing is a key challenge. Here, we studied and characterized the film by using a precursor solution of increased concentration, comparing it with the universally used 1-micrometer Sn-Pb perovskite film. The increase in molar concentration clearly induced thickness enhancement, but we observed that it also created numerous voids at the interface with bottom charge transporting layer. We hypothesized that these voids might hinder the increase in photocurrent associated with thickness enhancement. By introducing methylammonium chloride (MACl), we successfully fabricated Sn-Pb perovskite film with a thickness of 1.3 micrometer and no voids. Void-controlled Sn-Pb perovskite solar cells not only demonstrated superior short-circuit current density compared to those with voids but also operated smoothly under light exposure.