JPE Editor in Chief Sean Shaheen comments on the dramatic growth in the global photovoltaic industry, as it is accompanied by an increased diversity in the location and integration of solar installations.

We aim to investigate the properties of multilayer structures made of Cu and SiNx, focusing on their optical properties in relation to thermal treatment characteristics. The films were deposited on various substrates, including glass, quartz, and silicon, using radio-frequency magnetron sputtering and high-power impulse magnetron sputtering techniques. After deposition, the multilayers were subjected to thermal treatments at temperatures ranging from 100°C to 500°C. The most significant changes in optical properties occurred within the first 24 h after deposition. The multilayers exhibited stable optical properties up to 400°C in a nitrogen atmosphere. However, optical properties deteriorate at temperatures above 400°C due to interdiffusion between the layers. XRD analysis confirmed the crystallization of SiNx/Cu/SiNx multilayer and the oxidation of Cu layers beyond these temperature thresholds. We also revealed that the type of substrate used had only a minor impact on the optical properties of the multilayers. The SiNx/Cu/SiNx multilayer demonstrated promising optical properties and thermal stability, making them suitable for transparent heat reflector applications. The layers’ integrity and optical properties are compromised only at temperatures above 400°C.

The present investigation describes the optical properties of tin sulfide (SnS) thin films that were deposited on fluorine-doped tin oxide (FTO)-coated glass substrates at room temperature using the thermal evaporation method. The obtained films showed oriented growth with “p”-type conductivity. The effect of film thickness on the optical behavior of FTO/SnS was analyzed and compared with data from SnS films grown on glass and indium tin oxide substrates. Our study indicates that the properties of SnS film are independent of the substrate material. The optical band gap was found to decrease from 2.07 to 1.30 eV with increasing film thickness. We have seen a quantum confinement effect in samples whose grain size was less than 27 nm. The refractive indices of the samples were used to determine the single oscillator and dispersion energies using the Wemple–DiDomenico single-oscillator model. Other optical parameters were also determined using the transmission and absorption spectra. Besides grain size and number of defects, our data showed that the polarizability of the molecules along the Van der Waals direction influenced SnS optical properties. The interpretation was made possible considering the carrier concentration of free charges remained constant with varying film thickness. Such work provides insight into how to choose the appropriate thickness and, hence, grain sizes for optoelectronic applications.

Lead-halide perovskite solar cells (PSCs) have emerged as highly promising solar cells in recent years, due to their unique optical and electrical properties. Contrarily, the use of lead as one of the contents of such cells constitutes a vital problem to the community. In this study, we suggest various nanostructured designs in the absorber layer of such cells to reduce the lead content while enhancing cell performance. Full optical/electrical simulations of the PSCs are performed for the following cases: planar, cones nanostructured, and semi-ellipsoids nanostructured solar cells. The existence of these nanostructures enhances the absorption of light and consequently the short circuit current while using the same amount of lead-halide perovskite material. These nanostructures enhance the light absorption through two ways: increasing the light trapping, due to their geometrical structure, and enhancing the coupling of the incident light to the waveguide modes in the active layer. The findings of our study show that the implementation of nanostructures enables 33% reduction in the environmentally harmful lead content while still achieving a higher short circuit current. Moreover, the incorporation of nanostructures (conical and semi-ellipsoidal) in the PSC results in enhancements of the open circuit voltage, filling factor, and consequently the power conversion efficiency. The conical structures result in 17% efficiency enhancement compared to planar PSC with an absorber thickness of 200 nm. On the other hand, the semi-ellipsoidal structures achieve a remarkable efficiency enhancement of 27% for the same planar thickness.

A leaf-like structure is formed by placing luminescent plates in the vicinity of a luminescent fiber with their side surfaces facing the fiber. Its optical efficiency is expressed in terms of collection efficiency and absorptance of each luminescent component. This model allows one to calculate its optical efficiency under an arbitrary incident spectral photon flux. A clear lightguide can connect multiple fibers to transfer the photons generated by each leaf-like structure to a single photovoltaic cell. Thus, one can divide the incident area of a luminescent solar concentrator (LSC) into small regions without sacrificing its geometric gain. Lateral size reduction enhances its optical efficiency by alleviating the losses during the photon collection process. Other techniques reported for the conventional planar LSCs, such as edge mirrors and tandem structures, can be combined for further enhancement. In experiments, off-the-shelf luminescent components (2.0 mm-thick plates and 1.5 mm-diameter fibers) were used to assemble samples with various shapes. For example, the efficiency of collecting photons generated in the plates of a square device increased from 0.0052 to 0.024 by decreasing its side length from 50 to 10 mm and attaching mirrors on their outer edges. In contrast, optical efficiency is weakly dependent on leaf geometry, increasing design freedom on leaf shapes. The use of advanced luminescent materials as well as optimizing the leaf-like structure design would increase its optical efficiency further.

We aim to improve cell efficiency by developing optimal rear surface morphology for industrial tunnel oxide passivated contact (TOPCon) solar cells. Using a new chemical additive in the rear side polishing process, the pyramid base size can be increased from 2 to 10 μm to achieve a relatively flat surface for passivation improvement. As a result, the wafer minority carrier lifetime under new chemical additive condition measured at 5E15 cm−3 injection density by the Sinton WCT-120 tool was increased from 1865 to 3043 μs, and the implied open circuit voltage (iVoc) was also improved from 731.6 to 748.0 mV by comparing with the baseline of standard cell production (G1). The better passivation is due to the decreased surface recombination rate and more uniform passivation layer. However, the contact resistance was increased from 1.01 to 1.11 mΩ·cm2, which will result in a lower fill factor of TOPCon solar cells. To solve this contact problem, one more texture process was used to generate many small pyramids (1 μm size) on the larger pyramid bases. The contact resistance was successfully decreased from 1.11 to 0.87 mΩ·cm2. To check the final cell performance, TOPCon solar cells with different rear surface morphologies were also fabricated in the industrial mass production line. By comparing with the baseline of G1, our technology can increase the cell efficiency by 0.24% absolutely, and this technology can be applied to cell production directly.

Converting CO2 into hydrocarbon fuels is a promising strategy for alleviating global warming and addressing energy crises. However, the inefficient conversion of photocatalytic CO2 and H2O remains a significant challenge for its large-scale application. Herein, we prepare a monolithic catalyst NF@ZnO/CeO2, where ZnO nanorods and CeO2 were grown on the surface of Ni foam, effectively preventing catalyst aggregation. Under concentrated solar irradiation (4200 mW·cm−2), the CH4 yield increases 138 times from 1.11 to 153.09 μmol·cm−2. Regarding catalysts, the Z-scheme heterojunction structure formed between ZnO and CeO2 enhances light absorption ability and extends the lifetime of photogenerated charge carriers. As for concentrated solar irradiation, the heat energy induces the formation of oxygen vacancies on the CeO2 surface to promote CO2 molecular adsorption and activation and accelerates the electron and hole transfer rate at the CeO2/ZnO interface to overcome the reaction kinetic barriers. Moreover, concentrated solar irradiation enhances the density of photogenerated charge carriers and upshifts the Fermi level, while reducing the reaction barrier, thereby improving photocatalytic reduction conversion. This study demonstrates that the photothermal coupling effect induced by concentrated solar irradiation improves the efficiency of artificial photosynthesis for CH4, offering novel insights for developing sustainable energy and environmental protection.

Harnessing solar energy to convert CO2 into high-value-added products is a viable strategy to address the energy and climate crises. Nevertheless, the low photocatalytic effectiveness continues to be a critical factor limiting its practical application. We prepared Cu(II)-doped flower-like TiO2 nano-catalysts via ammonia etching and ion exchange methods. Under solar irradiation, the Cu-doped flower-like TiO2 efficiently converted CO2 and H2O to CH4, with a yield of 47.22 μmol/g. It was found that the unique multi-level structure of Cu-doped flower-like TiO2 exposed more active Cu sites and broadened the photo-response range of the catalyst. Moreover, Cu doping facilitated the separation and migration of photogenerated electron-hole pairs on the flower-like TiO2 surface, with the formed CuO sites acting as reductive active centers to augment the photocatalytic conversion of CO2 to CH4. We demonstrate that the synergy of Cu doping and the novel titanium-based material enhances the efficiency of artificial photosynthesis for CH4, opening up fresh insights for the evolution of sustainable energy and environmental protection.