Drawing on our reported light absorption enhancement strategy of planar meta-surface employed in solar cells, we extend it to photo-electrocatalytic water splitting and develop a one-dimensional model for this photocatalytic planar meta-surface. This model enables accurate calculations of the photocurrent density as a function of applied bias voltage; the simulation results agree well with experimental data in the literature. The underlying mechanism responsible for the superior photocatalytic performance of the planar meta-surface is elucidated by the comparison of its photo-carrier distributions to a conventional micron-scale film photo-electrode. Using a hematite planar meta-surface photo-anode as a representative case, the effects of carrier transport behaviors and key physical parameters on water splitting performance are systematically analyzed. The findings demonstrate that the photo-anode with optimized parameters can achieve significant enhancement in photocurrent and reduction in onset potential, offering theoretical insights and practical guidance for efficient solar-driven water splitting.
Photothermal-assisted photocatalysis, which couples localized thermal energy with photogenerated charge carriers to overcome thermodynamic and kinetic limitations, has emerged as an effective strategy for solar-driven CO2 reduction. Herein, nanoflower-like NiO/ZnO p-n heterojunction spheres were rationally constructed via a simple hydrothermal calcination method to achieve efficient concentrated photothermal-assisted CO2 reduction. The unique nanoflower morphology provides abundant interfacial contact between NiO and ZnO, while the formation of the p-n heterojunction establishes an internal electric field that suppresses electron-hole recombination. Under concentrated irradiation (4.31 W.cm(-2)), the photothermal coupling effect reduces the apparent activation energy and enables the NiO/ZnO photocatalyst to deliver CO and CH4 production rates of 51.78 and 15.96 mu mol.g(-1).h(-1), which are 7.92 and 9.61 times higher, respectively, than those obtained under nonconcentrated illumination. Photoelectrochemical measurements and in situ DRIFTS further reveal that the built-in electric field facilitates directional charge transfer from ZnO to NiO, thereby promoting CO2 adsorption and activation. We demonstrate an efficient photothermal-coupling strategy to construct high-performance catalysts for artificial photosynthesis and solar-to-fuel conversion.
We compare the capabilities of external and internal sensitizers in solar laser systems through numerical simulations. Three lasing media were studied: Nd:YAG, Nd:YAG with alexandrite as an external sensitizer, and Cr:Nd:YAG with Cr3+ ions as internal sensitizers. The Nd:YAG + alexandrite system showed a 1.38-fold efficiency gain over Nd:YAG without sensitizer, while Cr:Nd:YAG achieved a 1.34-fold improvement due to both radiative and nonradiative transfer mechanisms. Thermal analysis revealed that Cr:Nd:YAG becomes inoperative at input powers above 2.3 kW, whereas Nd:YAG and Nd:YAG + alexandrite remained stable up to 2.9 kW. It was shown that configurations based on external sensitization, in particular the Nd:YAG + alexandrite system, can provide both increased efficiency and excellent thermal stability, which offers clear advantages for high-power and long-term operation of solar lasers.
For wearable electronics applications, organic photovoltaic (OPV) cells are good candidates as sources of renewable energy. Many efforts have been devoted to increasing energy conversion efficiency in OPV cells, and improvement in light retention has been one of the main research directions. Within this context, our group recently proposed an OPV cell structure with a hemispherical-shell-shaped (HSS) active layer and discovered that it has high potential for substantial enhancement in absorption performance. As a continuation of the study, this paper reports an in-depth investigation of the proposed device, examining the effects of several design parameters on its absorption performance. Using finite element analysis, it is found that the absorption performance depends on the periodicity type, and that a hexagonal type results in higher absorption than a square one due to its closer shape resemblance to a circular cross-section. The absorption performance is also affected by a contact angle, i.e., the angle made between a sphere and a flat part of the structure. It is learned that the average integrated absorption generally increases along with the contact angle, which saturates at around 80 deg of contact angle. Lastly, the effects of a cell period are studied, and it turns out that the average integrated absorption decreases as the period increases. It is also observed that at high incidence angles (>similar to 75 deg ), an array with a shorter period results in lower absorption than one with a longer period owing to a partial obstruction issue. All of these results support the understanding that the primary contribution of absorption enhancement in the proposed HSS structure comes from improved light retention rather than from a simple advantage in active layer volume. It is envisaged that these study outcomes will provide important guidelines in the design of HSS OPV cells.
It has become a trend for the windows of modern buildings to be upgraded to smart windows with building-integrated photovoltaics (BIPVs). Smart windows are generally only used as outdoor photovoltaics to collect sunlight and generate electricity but are rarely used directly as indoor photovoltaics. We design a smart window with a sandwich structure, using a sandwiched a-Si bifacial semitransparent photovoltaic (BSTPV) cell to achieve double-sided collection and generation of indoor and outdoor light. The ethylene vinyl acetate (EVA) material that encapsulates the a-Si BSTPV cell is respectively doped with 0.9% yttrium aluminum garnet (YAG):Ce3+ phosphors and 0.8%YAG:Eu3+ phosphors, and its spectral down-shifting function is used to optimize the light source spectra, improve the spectral response of the a-Si BSTPV cell, and increase the conversion efficiency (PCE). Test results show that the PCE is relatively improved by no less than 5%. We expected to find application prospects for phosphor-in-EVA and further promote the development of BIPVs.
Diffuse (directional-hemispherical) and angular transmittance are critical figures of merit for wave optical light-trapping yet have never been available directly from finite-difference time-domain (FDTD) calculations. We introduce an FDTD post-processing formalism capable of returning absolute diffuse, direct, and total transmittance together with complete angle-resolved distributions, grounded in in-house open-source package coded for seamless integration with optimization workflows and for independent verification. The reliability of this method is demonstrated by simulating three canonical crystalline-silicon architectures: a planar reference, periodic micrometric upright pyramids, and photonic nanovoids. From the resulting angular power maps, we extract the silicon critical angle and quantify the portion of incident light retained by total internal reflection in each design, thereby establishing a rigorous link between optical scattering and carrier-generation potential. The wavelength-scaled nanovoid coating sustains broadband diffusion, converting incoming solar radiation into scattering angles that maximize optical path length. By providing a standard-compliant, parameter-driven route to diffuse and angular transmittance, the proposed formalism eliminates laboratory integrating-sphere measurements from the design loop and compresses development cycles from weeks to hours. Beyond photovoltaic modules, this architecture-agnostic framework is readily extensible to American Society for Testing and Materials (ASTM)- or International Organization for Standardization (ISO)-based standards and other photonic systems, enabling a truly simulate-to-specification paradigm for large-scale manufacturing and rapid materials discovery.
Attaining efficient and stable TEM00-mode laser emission is a key challenge solar laser research, suited especially well for applications requiring low laser beam divergence and high flux level at a laser beam focal spot. The concept of the simultaneous solar pumping of multiple thin Ce:Nd:YAG rods constitutes an effective solution for enhancing laser output beam quality, power stability, and scalability. However, to the best of our knowledge, there is no report on the successful simultaneous emission of multiple TEM00-mode continuous-wave (cw) solar laser beams from a single-pump cavity. We, therefore, present here the first simultaneous emission of three 1064 nm TEM00-mode cw solar laser beams from a single laser head composed of a fused silica aspheric lens, a conical pump cavity, and three 2-mm diameter, 25-mm length Ce:Nd:YAG rods, which were actively cooled by water and solar-pumped through a heliostat-parabolic solar energy collection and concentration system of Proc & eacute;d & eacute;s Mat & eacute;riaux et Energie Solaire - Centre National de la Recherche Scientifique (PROMES-CNRS). For 0.389m(2) effective solar collection area, 2.61 W total TEM00-mode cw solar laser power from the three laser beams was measured, corresponding to 6.71W/m(2) collection efficiency and 0.71% solar-to-laser power conversion efficiency, surpassing the previous records, attained using a single Ce:Nd:YAG rod and the same solar facility, by the factors of 1.43 and 1.13, respectively.
Passive radiative cooling is a promising cooling technology that emits heat to deep space without energy consumption. However, the persistent overcooling phenomenon in static radiative techniques has raised concerns. Here, we propose a high-performance adaptive metasurface radiative cooling device composed of a simple sandwich structure (Ag/Si/patterned VO2). The simulation results of electromagnetic fields confirm that the VO2 metasurface induces multiple resonant modes, significantly enhancing the thermal emissivity of the temperature-adaptive metasurface radiative device. As the temperature changes, the average emissivity in the atmospheric window switches from 20.5% to 90.9%, with a low solar absorptance of 33%. When applied to electronics, this device not only prevents overcooling but also delivers a net cooling power of 69.71 W/m(2) during daytime and 106.87 W/m(2) at night, enabling efficient thermal dissipation for electronic components. In addition, the adaptive radiative cooler maintains stable selective emissivity under varying incident angles and heat transfer coefficients, meeting the complex installation environments of electronic equipment. This provides a maintenance-free thermal management solution for high-density electronic systems.
The performance of an agriphotovoltaic system was studied from the viewpoint of both the crop yield of Japanese rice in a paddy field plant and the photovoltaic (PV) electricity production cost. The PV panels with a total rated output of 45,760 W were integrated onto a cost-effective dual-axis sun-tracking system and positioned at 3 m above the ground at the rice paddy field of 830 m(2) area. We show that the crop yield is strongly correlated with the amount of solar irradiation. By optimizing the operating mode and shading rate of PV panels, a crop yield of higher than 80% as compared to the average crop yield in the surrounding area has been satisfactorily achieved. The annual PV electricity produced amounted to an estimate of 43,995 kWh in the case-study period, and a specific yield of 961.4 kWh/kW was obtained. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication,
Semitransparent building-integrated photovoltaic (BIPV) is a promising energy generation approach that integrates photovoltaic technologies into buildings to harvest abundant solar energy. Semitransparent perovskite solar cells (PSCs) have advantages over widely used silicon (Si) cells and are more suitable for BIPV applications. We use rare-earth (RE) functional glass as packaging that can convert ultraviolet (UV) light into visible (VIS) light, which effectively reduces the UV degradation of PSCs and improves cell conversion efficiency (CE). Experiments show that the photoelectric conversion efficiency of the PSC is relatively improved by 10.12%, indicating that the model of the RE glass-PSC-BIPV is a useful attempt. (c) 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)
In photovoltaic devices, hot electrons generated by the absorption of solar energy typically thermalize by dissipating energy to phonons. The presence of hot optical phonons can inhibit the thermalization of electrons, thus facilitating a stable hot electron population. The significantly larger phonon band gap between optical and acoustic phonons in AlSb (relative to InAs) suppresses the scattering of optical phonons by lower frequency phonons, thus diminishing energy loss from higher energy phonons, creating the potential of hot phonons. By modifying the InAs/AlSb superlattice composition to be AlSb dominant, similar scattering behavior in the superlattice can be achieved, through a larger effective "phonon frequency gap" in AlSb-rich superlattice. In this work, we study phonon scattering rates in InAs/AlSb superlattices as a function of superlattice composition using first-principles methods based on deriving the harmonic and anharmonic interatomic force constants from density-functional theory and using them in a solution of the phonon Boltzmann transport equation. Computations are performed for four superlattices with compositions ranging from AlSb-rich to InAs-rich (93.75% AlSb, 87.5% AlSb, 12.5% AlSb, and 6.25% AlSb). Average phonon scattering rates of high-energy phonons through decay into lower energy phonons are found to be lower in the AlSb-rich superlattices. These lower scattering rates in the AlSb-rich superlattices can have important implications for the design of high-efficiency hot carrier solar cells.
The concept of passive radiative cooling has attracted considerable interest, but the cooling power is inherently limited by Planck's law. It has been revealed by recent research that the enhancement of radiation power has been closely associated with the application of positive photon chemical potential, though this process requires an external energy supply. We propose a self-sustaining thermodynamic configuration that couples a heat engine with a thermoradiative diode (TRD). This integrated system enables autonomous generation of positive photon chemical potential and enhancement of cooling power. Our findings suggest that integrating a TRD and a thermoelectric generator (TEG) has the potential to enhance cooling power effectively. Theoretically, with an emitter temperature of 293 K, the combination of a TRD and a Carnot engine has the potential to achieve a maximum cooling power of up to 485 W/m(2). This maximum cooling power has the potential to surpass the blackbody radiation intensity at 300 K, which is 459 W/m(2). The theoretical result indicates that the synergistic interaction between TRD and heat engines represents a new approach to enhancing radiative cooling.
We report on a microscopic quantum transport simulation of hot-carrier filtering across potential barriers formed by InP-InAs heterostructures in InAs nanowires with spatially localized monochromatic illumination. Qualitative agreement with the experimentally observed dependence of the extracted current on photon energy and localized source position is demonstrated. In addition, the impact on the hot-carrier extraction efficiency of carrier relaxation due to electron-phonon interaction is analyzed, and the inadequacy of the macroscopic drift-diffusion picture is confirmed.
We investigate the performance of thin-film solar cells incorporating InAs/GaAs quantum dots (QDs) and GaSb/GaAs quantum rings (QRs). The goal is to compare their impact on key parameters such as short-circuit current density and open-circuit voltage, with a focus on recombination suppression and light absorption properties. InAs/GaAs QDs with a type-I band structure show a higher light absorption, whereas GaSb/GaAs QRs with a type-II band structure exhibit a suppressed carrier recombination. Experimental results indicate that QR-based solar cells can reach higher efficiencies due to reduced carrier recombination, despite their lower absorption compared with QD-based solar cells. The findings suggest that GaSb/GaAs QRs offer a promising potential for enhancing solar cell performance through improved carrier lifetimes and reduced recombination losses.
Hot-carrier solar cells (HCSCs) offer the potential to enhance the energy-conversion efficiency of photovoltaic devices up to 86%. However, most HCSC models to date assume that electrons and holes have the same temperature, whereas many reports in III to V materials indicate that electrons can be much hotter than their counterparts. We present a detailed balance HCSC model that includes different temperatures for electrons and holes. We focus on the impact of the temperature imbalance on the voltage of such an HCSC and its power-conversion efficiency. Surprisingly, a temperature imbalance at a fixed effective temperature leads to a slight power-conversion efficiency increase, up to 1 to 2 percentage points, primarily due to an increase in fill factor and possibly open-circuit voltage. Yet, we show that the knowledge of the effective temperature alone is sufficient to design a satisfying HCSC. (c) 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)
Hot carrier solar cells require an absorber layer, which inhibits the thermalization of photogenerated carriers. Although such absorbers have been experimentally demonstrated, the specific mechanics of carrier thermalization are not fully understood. AlAs0.16Sb0.84/InAs in particular is an interesting material system due to its type-II band alignment and the possibility of a phonon bottleneck. We calculate steady-state carrier distributions under laser excitation in AlAs0.16Sb0.84/InAs multi-quantum well structures. Carrier temperatures are extracted from these distributions and compared with experimental results. Due to the large depth of the wells, a more sophisticated Schr & ouml;dinger solver that accounted for non-parabolic effects was implemented. Carrier recombination was modeled via an ABC model that used parameters obtained from experimental data. We achieved insight into how the non-equilibrium phonon interacts with the hot carriers and acts to inhibit thermalization as well as how Pauli blocking can affect this interaction. The picture is more complicated than previously described, with different ranges of the phonon wavenumber q interacting preferentially with different ranges of carrier energies. In addition, the effect of the electron-hole interaction on the carrier temperature over varying barrier widths was investigated. To match the experiment, larger longitudinal optical phonon lifetimes had to be used compared with bulk values used previously. (c) 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)
Halide perovskite solar cells have become a subject of interest in the photovoltaic domain due to their low cost and simple fabrication methodology. However, the presence of poisonous lead and stability issues have hampered their viability for commercialization. The advent of lead-free double perovskite such as Cs2AgBiBr6Cs2AgBiBr6 has attracted significant attention. We modeled and analyzed a lead-free perovskite solar cell (PSC), based on Cs2AgBiBr6Cs2AgBiBr6 with various charge transport layers, to obtain the most efficient configuration with the architecture FTO/ZnO/Cs2AgBiBr6/CFTS/AuFTO/ZnO/Cs2AgBiBr6/CFTS/Au. The device presents a power conversion efficiency (PCE) of 15.652%, fill factor (FF) of 62.926, current density (JscJsc) of 22.085mA/cm222.085mA/cm2, and open circuit voltage (VocVoc) of 1.126 V. After a comprehensive optimization of layer parameters to include the thickness of the electron transport layer (ETL) and absorber, ETL doping concentration, hole transport layer (HTL) and absorber, defect density of absorber, ETL/absorber and absorber/HTL, and ETL electron affinity, the following optimal values were obtained: 0.04 and 0.4 mu m0.4 mu m, 10181018, 10221022 and 1019cm-31019cm-3, 10141014, 10101010 and 1010cm-21010cm-2, and 4.0 eV. The final optimized PSC with the aforementioned optimal layer values shows a PCE of 25.562%, FF of 89.958%, JscJsc of 19.978mA/cm219.978mA/cm2, and VocVoc of 1.422 V. This performance demonstrates a 38.768% enhancement in PCE over the unoptimized device. The effects of operating temperature, work function of indium tin oxide (ITO), and metal back contact, alongside series resistance and shunt resistance, were evaluated on the optimized device. The resulting metric data obtained from our studies were compared with previously documented literature and showcase the study's contributions in exploring alternative non-toxic, inorganic perovskite solar photovoltaics (PV), with potential to serve as a steering tool for PV advancement.
We present the design and fabrication of bifacial perovskite solar cells that possess remarkable transparency to infrared light. Our approach involves the incorporation of an oxide-metal-oxide structure-based hybrid top transparent electrode (TE) consisting of NiO/Ag/NiO (NAN). With feedback from optical modeling, NAN-TE was successfully fabricated with electrical sheet resistance as low as 5.04 Omega/sq, along with an average visible transmittance of similar to 80%, using a low-energy adatom-based physical vapor deposition technique. Incorporating the fabricated TE in the device configuration of ITO/SnO2/MAPbI(3)/Sprio-OMeTAD/NAN, a power conversion efficiency (PCE) of 9.05% and 6.54% was achieved when illuminated from the ITO and NAN side, respectively, demonstrating a high bifacility factor of 72%. In comparison, an opaque device showed a PCE of 13.61%. The devices also showed high durability, retaining 80% of their initial PCE for over 1000 h without any encapsulation in ambient environmental conditions. The device also exhibited significantly high light transmission (similar to 40%) in the 800- to 1200-nm near-infrared region. Furthermore, our NAN-TE has a total thickness of <40 nm, making it a potential TE for various optoelectronic applications due to its carefully engineered optical design. The demonstrated NAN-TE has immense potential to achieve outstanding performance in building integrated photovoltaics and tandem applications.
Agrivoltaic systems offer innovative solutions to pressing global challenges such as climate change, renewable energy production, and food security. Specifically, horizontal single-axis tracker agrivoltaic systems can mitigate agricultural yield losses through optimized tracking strategies that balance light distribution between crops and solar panels. This paper presents a methodology for dynamically optimizing solar panel positioning to meet the varying light requirements of crops. Simulations are conducted for a case study of an agrivoltaic system in an apple orchard in southwestern Germany. Conventional shading strategies for apple orchards, based on agronomic experience and hail nets, are challenged, and specific irradiance targets for regional apple varieties are proposed, expressed in W/m(2) or Wh/m(2)/day. Unlike estimated relative shading percentages, these absolute targets facilitate optimization and ensure consistent light availability, addressing issues related to weather variability. The analysis, focusing on tree light availability, is performed using the custom-developed tool APyV. Results indicate that 91% of the target irradiation for apples can be achieved in the simulated year with tailored PV control, resulting in a moderate 20% reduction in electrical yield. Periods when apple light requirements are not met are identified, highlighting the limitations of crop-based optimization. These findings provide valuable guidance for future optimizations that better balance electrical yield with agronomic effectiveness. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
