Passivation of surface defects at the interface between perovskite absorber layers and charge transport layers is important for reducing ion migration and nonradiative recombination, thereby improving the performance of perovskite photovoltaics. In indoor photovoltaics, the bandgap of the perovskite absorber layer must be engineered to optimize device performance, typically through compositional tuning of the precursor materials. Passivation becomes even more relevant when light intensity levels are low, as fewer charge carriers are generated and recombination can be much more detrimental. Herein, we simultaneously apply composition and anti-solvent engineering, varying bromine content in the perovskite and using chlorobenzene or dichlorobenzene, with phenethylammonium salts as interfacial passivators to (i) increase the crystallinity and grain sizes of the perovskite absorber layer, (ii) form a quasi-2D/3D perovskite heterojunction to passivate surface defects, and (iii) demonstrate light-intensity-dependent stability behavior. The optimized perovskite indoor photovoltaic devices with an aperture area of 0.093 cm2, using dichlorobenzene as the anti-solvent and phenethylammonium bromide as the passivation salt, achieved an improved efficiency of 36.2% with a power output of 112.2 μW cm−2, a fill factor of 76.5%, an open-circuit voltage of 1.04 V, and a short-circuit current density of 141.28 μA cm−2 under 1000 lux.
Solar-driven catalytic technologies offer alternative pathways for addressing global challenges in energy sustainability and environmental remediation. Photocatalysis and photoelectrocatalysis have received considerable attention for their potential to convert abundant solar energy into chemical fuels and value-added products. Despite remarkable progress over the past decades, the practical implementation of these technologies still faces major challenges, including limited light utilization, rapid charge recombination, and an insufficiently explored understanding of reaction mechanisms. This Editorial briefly summarizes the current state of the art in photocatalysis and highlights future research directions with a focus on advanced material design and mechanistic investigations.
This Special Topic in APL Energy highlights recent advances in applied energy research across Latin America, focusing on materials and technologies that support the regional energy transition. The collection showcases developments in organic and perovskite photovoltaics, perovskite quantum dots, photocatalysis, and photoelectrochemical hydrogen production, including both fundamental studies and prototype-level innovations. Together, these contributions, along with the vast renewable energy potential that Latin America possesses, demonstrate the region’s growing capacity for scientific innovation, interdisciplinary collaboration, and technology development tailored to local resources and challenges, reinforcing Latin America’s role in shaping sustainable, low-carbon energy solutions.
Graphene-oxide (GO) and reduced graphene-oxide (rGO) are known to offer many potentials for a wide range of applications. A new method of development based on the concepts of Hummer’s and modified Hummer’s methods is used to synthesize GO, which was subsequently chemically reduced to magnetic rGO using sodium borohydride (NaBH4). The morphological quality, elemental analysis, functional groups, and crystalline size of graphite, GO, and rGO have been studied. GO and rGO exhibit wrinkled-stacked flakes and crumpled thin sheets, respectively, in contrast to graphite, which has a platelet-like surface. Fourier transform infrared spectroscopy analysis demonstrates that GO has more oxygen-rich functional groups than rGO and graphite. The distinctive peaks for graphite, GO, and rGO are revealed by x-ray diffraction at 26.4°, 10.6°, and 17.4°, respectively. Furthermore, using a vibrating sample magnetometer, rGO shows ferromagnetic behavior with a magnetization of 0.32 emu/g and a coercivity of 205 Oe at 300 K, while graphite and GO do not. The presence of passivated C–H bonds converted rGO from a non-magnetic carbon material into a defect-driven, exchange-coupled magnetic system. The outcomes open a new route for new magnetic materials and their potential for future applications in spintronics and quantum computing at room temperature.
We tailor the Low-Vacuum Proximity-Space Effusion (LV-PSE) method for high-rate, sequential two-step evaporation of MAPbI3 perovskite films. By combining ordered PbI2 growth with enhanced MAI intercalation, LV-PSE achieves a MAPbI3 growth rate of 23 nm/min, surpassing co-deposition benchmarks, while providing better control over each precursor deposition. A short source–substrate distance (2 cm) increases local vapor flux on the substrate and enables pressure (0.8–4 × 10−2 mbar) and temperature (15–100 °C) to control the rate for producing high-quality MAPbI3 films (100–520 nm) with broad applicability. Continuous, dynamic intercalation, inherent to the LV-PSE working scheme, helps overcome thickness limitations. Using molecular dynamics with machine-learned interatomic potentials, we observe early PbI2 lattice disaggregation during MAI intercalation (nanosecond scale) before crystallization. A proof of concept for the integration of the MAPbI3 film into a p–i–n device architecture on ITO/PTAA, using evaporated C60/BCP/Ag as the top electrode, has been provided. Compared with high-vacuum PVD, LV-PSE reduces system complexity, minimizes material use and waste, and lowers maintenance needs. The study of process–material relationships offers key insights into perovskite formation mechanisms, provides an application-oriented parameterization for perovskite fabrication using advanced sublimation–evaporation tools, and can foster further technological development.
Designing an effective microstructure to further optimize the separation efficiency of bulk and in-plane charge carriers of 2D semiconductor materials is of great significance for optimal photocatalytic efficiency. In this paper, a porous Bi5O7I nanosheet with abundant oxygen vacancies was constructed by controlling the iodine removal process under inert atmosphere conditions to optimize the photocatalytic performance. By controlling the proportion of raw materials, the oxidation capacity of the solvent in the hydrothermal reaction can be adjusted to oxidize bismuth to a higher chemical valence state, which can skillfully promote the further oxidation and sublimation of iodine at high temperature to achieve the pore-building effect. Meanwhile, the samples prepared under an inert atmosphere not only exhibited a typical two-dimensional porous structure but also displayed abundant oxygen vacancies, compared with the samples prepared under a traditional air atmosphere. Furthermore, the 2D porous structure reduced the recombination probability of in-plane charge carriers, presented weak charge transfer resistance, and improved redox capacity due to the loss of iodine. In particular, the sample calcined at 450 °C with 20 nm pores uniformly distributed on the surface exhibited the best photocatalytic degradation activity and stability. The preparation of porous nanosheets provides a reference for improving the in-plane charge carrier separation efficiency of two-dimensional semiconductor materials, and is conducive to the design and preparation of bismuth-based semiconductor materials with excellent photocatalytic performance.
Cu2ZnSnS4 (CZTS) is a promising kesterite semiconductor for sustainable photovoltaic applications, offering advantages such as high optical absorption, bandgap tunability, and eco-friendly, earth-abundant elements. However, while solution-processed CZTS has shown potential, key gaps remain in understanding their optoelectronic properties, particularly how sulfur (S) and selenium (Se) influence phase segregation and bandgap grading. Furthermore, the wide-bandgap CZTS suffers from a significant open-circuit voltage (VOC) deficit, limiting its efficiency. In this study, we fabricated solution-processed wide-bandgap Ag0.1(Cu0.9)2 ZnSnS4 solar cells, achieving a remarkably high VOC of 770 mV [58.5% of (VOCSQ)]. We compared the pure-sulfide wide-bandgap films, which formed a single kesterite layer, with narrow-bandgap Ag0.1(Cu0.9)2ZnSn(S,Se)4 films, which exhibited a dual-layer structure. Advanced characterization techniques, including scanning electron microscopy and scanning transmission electron microscopy, revealed Zn-rich and Sn-rich phase segregation for narrow-bandgap films, while back-side Raman spectroscopy showed depth-dependent compositional gradients. The incorporation of Se in the narrow-bandgap films led to improved carrier dynamics, reduced defect density, and enhanced device performance, with a significant increase in efficiency compared to the wide-bandgap films. These findings emphasize how S and Se tuning can modulate phase behavior, enabling the design of CZTSSe materials with tailored bandgaps and optimized optoelectronic properties for high-efficiency, environmentally sustainable solar cells.
Narrow-temperature-fluctuation waste heat is abundant in data centers. Ferroelectric materials exhibit the pyroelectric effect, which enables direct conversion of thermal energy into electricity. Power-source-free pyroelectric energy conversion is a new approach that generates electricity without any external bias or battery connection. It represents a bias-field-free thermodynamic cycle that fundamentally differs from the conventional Olsen/Ericsson cycles. The device performance is governed by a figure-of-merit that considers both the pyroelectric coefficient and the latent heat across the phase transformation. Long-cycle electricity generation is achieved by continuously driven phase transformations. Recent progress has demonstrated microampere-level electricity output over more than 7000 phase-transformation cycles, showing compelling potential for practical applications. This review summarizes the fundamental mechanisms, material design strategies, device demonstrations, and future outlook of power-source-free pyroelectric conversion. We aim to provide a comprehensive understanding of this emerging method and offer useful insights for long-cycle electricity generation from waste heat in data centers.
Sulfide chalcopyrite, Cu(In,Ga)S-2, having a wide bandgap (>1.5 eV), favorable optoelectronic properties, and high stability, is a promising top-cell absorber for tandem applications. Adapting device structures optimized for 1.0-1.2 eV absorbers to wide bandgap absorbers requires modification of the buffer layer. This study investigates atomic layer deposition of ZnSnOx as an alternative buffer layer to conventional CdS. Critical parameters for buffer performance are the conduction band offsets at both interfaces of the buffer. To investigate these buffers, we electrically characterize solar cells utilizing different compositions of ZnSnOx. The [Sn]/([Sn] + [Zn]) atomic ratio is controlled by the ratio of Zn-O to Sn-O cycles during atomic layer deposition. Solar cells were fabricated utilizing CuInSe2, Cu(In,Ga)Se-2, and Cu(In,Ga)S-2 absorbers. These absorbers vary in their conduction band minimum energy. Varying buffer composition has two primary effects on cell performance: (1) Low tin buffers decrease the activation energy of interface recombination, reducing open circuit voltage. These observations indicate a cliff, a decrease in the conduction band minimum from absorber to buffer. (2) High tin buffers reduce the fill factor and, in some cases, even reduce the short circuit current. This observation indicates an electron transport barrier, large conduction band offsets, which limit the transport of electrons across the buffer in either direction. Comparing different absorbers, cliffs occur at lower Sn contents, and the effects of barriers are more dramatic for absorbers with lower conduction band minima. We conclude that increasing tin content shifts the conduction band minimum of these buffers upward.
Proton-conducting ceramic cells (PCCs) enable high-efficiency energy conversion and storage at intermediate temperatures (400–600 °C) while offering lower operational costs and improved durability compared to oxygen-ion-conducting cells. However, their adoption is limited by their low electrocatalytic activity and high polarization resistance. Electrode surface modification has emerged as a compelling strategy for improving electrode activity and durability. This Review examines three approaches that have demonstrated performance enhancements in PCCs: (1) infiltration of catalytically active materials into a porous electrode scaffold, (2) exsolution of metallic and oxide phases under tailored redox conditions to generate active sites, and (3) pulsed laser and atomic-layer thin-film depositions for surface engineering. The fundamental mechanisms and crucial physical factors underlying each strategy are discussed, along with advanced characterization techniques that provide insight into the in situ growth, structural evolution, and phase transformation of active materials. Finally, we highlight the challenges associated with these techniques and recommend future research directions to accelerate the development of PCC technology for commercial applications.
Perovskite solar cells (PSCs) have witnessed significant achievements in terms of power conversion efficiency, and the focus has now shifted toward outdoor operational stability. It has been well established that PSCs exhibit diurnal, reversible performance dynamics outdoors, where they are exposed to different daytime and nighttime temperatures along with varying sun irradiance. This brief perspective discusses the role of temperature in device performance degradation. While temperatures during illumination periods are known to accelerate photodegradation, we stress the importance of nighttime temperatures in affecting PSC degradation and recovery, hence the overall power yield. This adds to the significant temperature effects on photostability and hints that both temperature effects should be understood toward a full prediction of the long-term performance of perovskite-based devices.
All-polymer thermoelectric (TE) modules have emerged as viable solutions for sustainable energy harvesting, particularly in low-power Internet of Things (IoT) applications. This study proposes a fully metal-free all-polymer TE module fabricated using poly(benzodifurandione) (PBFDO) as the n-type material and PEDOT:PSS as the p-type material. The anisotropic TE behavior of PBFDO was comprehensively evaluated by comparing its in-plane and through-plane properties. Unlike previous designs that incorporated metal or interfacial layers for electrical connections, the proposed module employs a direct lamination process, eliminating the need for metal electrodes while maintaining low interfacial resistance. Notably, the device exhibits excellent long-term stability, maintaining consistent interfacial resistance for more than a year. With a power density exceeding 30 μW/cm2 at 100 °C under natural convection, the proposed module can sustainably power Bluetooth low-energy sensors. In addition, it demonstrates thermal degradability at temperatures exceeding 400 °C, enabling its disposal as burnable waste. These findings highlight the viability of fully organic TE modules as sustainable and eco-friendly energy sources for IoT applications.
Perovskite solar cells stand out due to their excellent optoelectronic properties, relatively simple fabrication methods, and tunable bandgaps. Consequently, their wide-bandgap variants (1.65–2.0 eV) are particularly well-suited for use as top cells in tandem solar cell configurations. However, their development remains hindered by certain challenges, such as halide segregation and high defect density. While previous reviews have summarized advances in this field, there is a lack of a comprehensive discussion that spans from challenges to development and applications. This article, from the perspectives of material and process optimization, specifically focuses on the latest breakthroughs achieved over the past year. It systematically outlines strategies, including additive engineering, crystallization kinetics regulation, and interface engineering, to realize defect passivation, film quality improvement, and device performance enhancement. This review not only delves into the mechanistic understanding of halide segregation but also analyzes recent research progress on the integration of wide-bandgap perovskite top cells with various bottom cells, such as copper indium gallium selenide, silicon, narrow-bandgap perovskites, and organic solar cells. Finally, it highlights future research directions, emphasizing that addressing the intrinsic stability of materials and clarifying the microscopic mechanisms of phase segregation are crucial for advancing their industrial applications.
This work investigates proton conduction through a wide range of 2D graphene-like crystals using density functional theory calculations. Our goal focused on understanding the impact of the membrane’s chemical constitution on proton permeability, with particular attention to the effect of sequential substitution using non-metallic elements such as boron, nitrogen, silicon, sulfur, and phosphorus. Results indicate that boron-doped graphene reduces the proton permeation energy barrier, being comparable with values for hexagonal boron nitride. In contrast, nitrogen-doped graphene exhibits a significantly high energy barrier (>4 eV) for proton permeation, suggesting that it is unlikely to support proton conduction at room temperature without having defects on the 2D-monolayer. The use of other elements (O, Si, S, and P) generates a broad spectrum of energy barriers, with distinct trends correlating to changes in pore size driven by the elongation or contraction of the 6-membered rings containing the dopants. In comparison, pure 2D-materials such as phosphorene, silicene, and germanene also arise as promising candidates for proton exchange membrane (PEM) applications due to relatively low proton permeation barriers. However, the increased pore size in these materials may reduce their impermeability to other gases, potentially affecting the performance of the PEM. In addition, we further examined the synergistic effects of multi-element 2D materials, with gallium nitride emerging as a candidate capable of simultaneously enhancing proton permeability and improving membrane mechanical and thermal robustness. This work highlights the importance of exploring additional hetero-doped 2D-materials, where untapped chemical properties may offer further opportunities for optimizing PEM performance.
Silicon (Si) is a promising anode material for next-generation lithium-ion batteries owing to its high theoretical capacity; however, its large volume changes during lithiation and delithiation lead to interfacial delamination and rapid capacity fading. Here, we demonstrate that inserting Au nanoparticles (NPs) between Si and a Ta substrate effectively enhances the adhesion and electrochemical stability of Si thin-film anodes. The sample with uniformly distributed Au nanoparticles (∼10 nm) exhibited the best performance, maintaining a discharge capacity of ∼2360 mAh g−1 after 100 cycles at 1 C (about 70% of its initial capacity). Electron microscopy analyses revealed that the Au NPs acted as mechanical anchors at the Si/Ta interface, preventing delamination and preserving electrical contact during repeated cycling. These results highlight that nanoscale interface engineering using Au NPs is a simple and effective approach to achieve durable, high-capacity Si thin-film anodes for advanced lithium-ion batteries.
In this article, we show the measurement of the magneto-thermoelectric effect (spin Seebeck and anomalous Nernst effects) of bulk composite pellets prepared from nanopowders of Fe3O4 and Pt. We compare structural, magnetic, and thermoelectric data as the Pt% is increased against a control series of pellets, where sintering temperature and time are varied and a 5 nm layer of Pt is sputtered onto the surface. We also compare the measured thermoelectric efficiency and figure of merit of the composite pellets to our control and a benchmark thin film, where we find an order-of-magnitude increase. This suggests that composite pellets could be a route forward in scaling up the spin Seebeck effect from thin film to bulk.
A photoelectrochemical reactor designed and fabricated from ABS using 3D printing with geometric simplicity and modular assembly is presented, which facilitates flexible scaling and easy adaptation to diverse experimental configurations. It is specifically intended for the evaluation of photoelectrodes aimed at green hydrogen production through water photoelectrolysis. The system displays a dual-compartment configuration separated by a gas-selective membrane, enabling precise characterization of PEC (photoelectrochemical cell) devices. The proof of concept demonstrates the functionality of reactor under laboratory conditions, reaching a current Technology Readiness Level (TRL) between 3 and 4, with ongoing development toward higher TRLs through materials optimization and extended stability testing. The reactor represents a promising approach due to its low cost, scalability, compact integration, and potential to enable future solar-powered hydrogen production. Its accessible design makes it particularly suitable for educational environments and training in solar fuel technologies. With a realistic pathway for scaling to higher TRLs, the system serves as a flexible platform for continued innovation. Furthermore, its compact and energy-efficient configuration positions it as a reliable candidate for future integration with autonomous solar setups, supporting decentralized hydrogen generation.
Waste heat harvesting of industrial processes is necessary to improve energy efficiency, reduce environmental impact, and, in the best cases, also pay off economically. Consequently, many different harvesting systems have been developed, but for temperatures below 100 °C, a mature technology that achieves sufficient efficiency and output power is not yet available. Here, we focus on thermoelastic harvesting, which uses shape-memory alloy wires as active materials. We demonstrate that the cycle frequency and, thus, the output power of a thermoelastic harvesting system can be increased by replacing the common fluid flow axial to the wire with a transverse flow. This results in simultaneous heat exchange along the length of the wire. This improvement in timing allows one to increase the wire length and cycle frequency, both of which increase output power, effectively enabling the upscaling of thermoelastic devices. We validate our approach through in-operando experiments for a 1 mm thick wire and demonstrate that transverse flow allows us to increase the switching frequency from 1 to 11 Hz, which increases output power by a factor of 4.3. As slow frequency is also a shortcoming of other ferroic harvesting and cooling devices, we discuss the feasibility of our timing approach for these emerging technologies as well.
