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Self‐healing transparent polymers are advantageous for various optoelectronic devices to improve resilience and durability. However, most of these materials have been applied only as flat films and do not address the need for optical structures that can manipulate light. Here optical microstructures embossed on a self‐healing polyurea film are presented which can autonomously recover from damage in ambient conditions. The polyurea film have a high optical transmittance above 90% and haze below 1.3%, and Young's modulus of 3.4 MPa. When applied as a protective light‐trapping layer for perovskite solar cells, the champion device shows improved short circuit current density from 23.7 to 25.0 mA·cm−2, and power conversion efficiency from 21.5% to 23.0%. Furthermore, the solar cell with the light‐trapping layer has improved impact resistance and can recover its performance after being scratched. It is envisioned that self‐healing optical structures can be realized for different geometries and materials in a range of optoelectronic applications to produce resilient and durable devices. [ABSTRACT FROM AUTHOR]

Silicon (Si), the eighth most common element in the known universe by mass and widely applied in the industry of electronics chips and solar cells, rarely emerges as a pure element in the Earth's crust. Optimizing its manufacturing can be crucial in the global challenge of reducing the cost of renewable energy modules and implementing sustainable development goals in the future. In the industry of solar cells, this challenge is stimulating studies of ultrathin Si‐based architectures, which are rapidly attracting broad attention. Ultrathin solar cells require up to two orders of magnitude less Si than conventional solar cells, and owning to a flexible nature, they are opening applications in different industries that conventional cells do not yet serve. Despite these attractive factors, a difficulty in ultrathin Si solar cells is overcoming the weak light absorption at near‐infrared wavelengths. The primary goal in addressing this problem is scaling up cost‐effective and innovative textures for anti‐reflection and light‐trapping with shallower depth junctions, which can offer similar performances to traditional thick modules. This review provides an overview of this area of research, discussing this field both as science and engineering and highlighting present progress and future outlooks. [ABSTRACT FROM AUTHOR]

Abstract Silicon (Si), the eighth most common element in the known universe by mass and widely applied in the industry of electronics chips and solar cells, rarely emerges as a pure element in the Earth's crust. Optimizing its manufacturing can be crucial in the global challenge of reducing the cost of renewable energy modules and implementing sustainable development goals in the future. In the industry of solar cells, this challenge is stimulating studies of ultrathin Si‐based architectures, which are rapidly attracting broad attention. Ultrathin solar cells require up to two orders of magnitude less Si than conventional solar cells, and owning to a flexible nature, they are opening applications in different industries that conventional cells do not yet serve. Despite these attractive factors, a difficulty in ultrathin Si solar cells is overcoming the weak light absorption at near‐infrared wavelengths. The primary goal in addressing this problem is scaling up cost‐effective and innovative textures for anti‐reflection and light‐trapping with shallower depth junctions, which can offer similar performances to traditional thick modules. This review provides an overview of this area of research, discussing this field both as science and engineering and highlighting present progress and future outlooks.

Abstract Although studies of insect decline have recently dominated headlines worldwide, their interpretation requires caution since for most species, we lack long‐term population baselines. In the tropics, where most insect species thrive, our knowledge is even more limited and so reliable insect assessments must originate from well‐established long‐term monitoring efforts. Combining the extensive monitoring data from the Arthropod Program of the Smithsonian Tropical Research Institute (STRI) on Barro Colorado Island (BCI), Panama, we compare whether known arthropod diversity can be detected through metabarcoding of bulk insect samples obtained through automatic light‐trapping. Our study detected 4402 species based on Barcode Index Numbers (BIN) and detected fine‐scale differences between wet and dry seasons and sampling localities. We further refined our analysis to indicate which families and genera explained seasonal turnover. Using samples collected in parallel, but sorted manually as part of the ongoing arthropod monitoring program, we compared these methods. Out of 538 BINs recovered through manual sorting, there was a 70% overlap with the metabarcoding data; however, it represented 30% of the total BINs detected through metabarcoding. Expecting higher detection through metabarcoding, we also compare the results with the 14 years of sampling in BCI to better understand how well the monitoring program has captured the diversity of focal groups. Our results revealed a ~50% overlap between both methods and similar total catch. Barcode Index Numbers manually detected but not recovered by metabarcoding highlight some of the limitations of molecular detection methods such as primer bias. Contrastingly, BINs detected with metabarcoding, but not recovered by the traditional monitoring scheme, highlight the importance of local and regional barcode reference libraries.

Light-trapping micro- and nanostructures generated on various material surfaces have garnered significant interest in recent years due to their pivotal role in various scientific and technological applications. Direct laser writing has emerged as a prominent, versatile, and practical method for fabricating these structures. In this study, we employed nanosecond pulsed laser radiation to create light-trapping structures with diverse topologies. Through the texturing process, we achieved an average total reflectance of 13.6–16.9% across a wide wavelength range (250–2500 nm) on the surface of aluminum samples. Furthermore, we demonstrate the ability to modulate the infrared absorption of material surfaces by controlling the height of the resulting structures, which holds substantial importance for technological applications. [ABSTRACT FROM AUTHOR]

The incomplete absorption of light in the perovskite solar cells (PSCs) due to the escape of photons and the waste of their energy in the visible spectrum hinders the efficiency of this type of solar cell. Utilizing light-trapping nanostructures and stimulating the device's plasmonic is an efficient way to increase absorption and reduce the energy losses. In this paper, a novel configuration of a nanostructured PSC with a plasmonic enhancement has been introduced to confine light in the active layer and boost energy harvesting. According to the conducted calculations, the modified configuration supports 23.4% higher short-circuit current density (J SC) and 21% power conversion efficiency compared to the conventional PSC. In this study, the finite element method has been employed to perform numerical simulations of the examined structures. For modeling and characterizing solar cells, optical physics of the devices is used in conjunction with their electrical physics. [ABSTRACT FROM AUTHOR]

• Random pyramids with nano- to micro-scale widths fabricated in one-step process. • Random pyramids absorption is superior to photonic crystals at short wavelengths. • Photonic crystals absorption is superior to random pyramids at long wavelengths. • Ideal photocurrent densities of > 37 mA/cm2 reached for 10 µm thick silicon devices. • Alkaline etching of random pyramids can be utilized for silicon down to 10 µm. The potential of enabling a wide range of applications with lightweight, flexible, thin silicon photovoltaic (PV) devices has led to research interest in various light-trapping technologies for thin silicon absorbers. Herein, using both experiments and photonic modelling, we present a detailed comparison between random pyramid texturing and inverted pyramid photonic crystal patterning in thin silicon vis-à-vis light trapping. In particular, we investigate the potential of uniform single-dimension periodic structures in contrast to conventional multi-dimensional random structures for high broadband absorption efficiency in ultra-thin silicon. We find that inverted pyramid photonic crystals cause a large increase in optical path length especially for long wavelength photons due to strong wave interference producing exceptionally high absorption and so does random pyramids though with slightly lower absorption than that of photonic crystals. On the other hand, the random pyramids, fabricated via a one-step etching process with feature sizes ranging from sub-micron to 4 µm, have higher absorption at short wavelengths due to their multi-dimensional size distribution. Overall, we find that random textured pyramids appropriately fabricated can yield a comparable ideal photocurrent density to that by photonic crystals for 10 µm thick silicon. [ABSTRACT FROM AUTHOR]

Light-trapping structures formed on surfaces of various materials have attracted much attention in recent years due to their important role in many applications of science and technology. This article discusses various methods for manufacturing light-trapping "black" silicon, namely laser, chemical and hybrid chemical/laser ones. In addition to the widely explored laser texturing and chemical etching methods, we develop a hybrid chemical/laser texturing method, consisting in laser post-texturing of pyramidal structures obtained after chemical etching. After laser treatments the surface morphology was represented by a chaotic relief of microcones, while after chemical treatment it acquired a chaotic pyramidal relief. Moreover, laser texturing of preliminarily chemically microtextured silicon wafers is shown to take five-fold less time compared to bare flat silicon. In this case, the chemically/laser-treated samples exhibit average total reflectance in the spectral range of 250–1100 nm lower by 7–10% than after the purely chemical treatment. [ABSTRACT FROM AUTHOR]

It is difficult for metal-modified semiconductor nanotubes to obtain surface-enhanced Raman scattering (SERS) substrates through long-range ordered 3D assembly, which adversely affects both Raman signal enhancement and Raman signal uniformity. Here, ZnFe 2 O 4 nanotubes with Ag nanoparticles modified on the inner and outer walls are induced to grow on the surface of the ordered Si pyramid by ZnO nanonedles as sacrificial templates. In this way, the composite nanotubes (Ag/ZnFe 2 O 4) are assembled into dandelion flower-like 3D aggregates with a periodic arrangement of hexagonal close packing. This 3D ordered SERS substrate based on Ag/ZnFe 2 O 4 nanotubes has excellent anti-reflective performance and carrier separation ability, which is conducive to the enhancement of Raman signal. When the SERS substrate is used as a sensor, it can achieve the single molecule (10−13 M) detection level of Rhodamine 6 G, the enhancement factor (EF) is 3.14 × 109, and the linear fit (R2) of quantitative analysis is as high as 0.998 from 10−13 to 10−4 M. Meanwhile, the long-range ordered arrays on the SERS substrate can ensure the signal uniformity of sensor, which relative standard deviation (RSD) is as low as 3.37 %. In addition, the photocatalytic self-cleaning capability of SERS substrate ensures that the sensor can be reused. Finally, the mechanism of the photogenerated carrier migration of Ag/ZnFe 2 O 4 and its contribution to Raman signal enhancement were analyzed. • The SERS sensor with dandelion flower-like Ag/ZnFe 2 O 4 nanotubes was obtained. • The sensor can be applied to quantitative and qualitative analysis of trace dyes. • The sensor can be reused based on its photocatalytic self-cleaning capability. [ABSTRACT FROM AUTHOR]

Many light trap designs exist in the field of applied and basic entomology for catching moths, yet a robust comparative analysis of structural designs of such traps is lacking. Our study compares the performance of three different trap designs to assess the effect of presence/absence of vanes and their colour on trapping efficiency. LepiLED lamps were used in all traps as the light source. We hypothesized that traps with vanes (white and black) would perform better than the same trap with rods, since it improves flight interception of insects. Furthermore, we expected that between the two designs with vanes white would be more efficient than black due to a higher radiation emission and better visibility. The study was conducted between July and September 2021 at two locations in the nature reserve Jenaer Forst (Jena, Germany, N 50.926694, E 11.556583). At each location, we sampled in three understorey sites parallelly. The abundance, diversity and body size of 4432 moths belonging to 170 species and 12 different families were analysed. Traps with white vanes performed best with 10.5% more individuals and 7% more species than the trap with black vanes and with 19% more individuals and 16% more species than the traps with rods. Differences were significant between the two vane traps against rods, for both individuals and species, but differences between the two vane traps were not. In addition, traps with white vanes and with rods were tested indoors under controlled conditions for selected species. In four out of ten species, significantly more individuals were collected in the vane traps. We conclude that the use of vanes as a flight interception tool is important for improving the trapping efficiency. The colour of vanes is also likely to play a role because of an overall higher radiation emission and better visibility for insects. [ABSTRACT FROM AUTHOR]

Flexible perovskite photovoltaic devices are typically constructed on flexible polyethylene naphthalate (PEN) substrates, which exhibit near-ultraviolet absorption and high visible-light reflection, leading to significant optical losses. To address this issue, a reusable optical-management sticker tailored for flexible substrates has been proposed in this work. The sticker incorporates a light-shifting material that converts near-ultraviolet light into visible light, enabling photoelectric conversion of near-ultraviolet light. Additionally, the sticker features a light-trapping microstructure that creates a refractive index gradient from PEN to air, thereby achieving a significant anti-reflection effect. As a result, the efficiency of a flexible perovskite solar cell reached 23.05% (certified 22.46%) under 1 sun AM1.5G illumination and 36.65% (certified 34.03%) under 1000 lux artificial light illumination. Furthermore, scaling this solution to large-area modules has yielded remarkable improvements, achieving a breakthrough certified efficiency of 20.48% (aperture area 21 cm 2 ) in flexible perovskite photovoltaic modules., (© 2025 Wiley‐VCH GmbH.)

We compared the performance of three entomological LED lamps that differed in intensity and wavelength composition by using them to catch 2257 individuals of 161 species and 11 families of nocturnal Lepidoptera in two grassland habitats (dry grassland and orchard meadow). The study was carried out in June and July 2020 in the Jenzig conservation area (Jena, Germany, 50°56´12˝N, 11°37´37˝E). In each habitat, we sampled three microhabitats that were either exposed, moderately sheltered or sheltered. Data were analysed using generalized linear mixed models. A lamp with high radiant flux (LepiLED maxi: 1.34 W mixed radiation) attracted 37% more moths and 5% more species than a lamp with a lower radiant flux (LepiLED mini: 0.55 W mixed radiation). The maxi lamp also attracted 17% more moths and 6% more species than the same lamp with UV radiation only (LepiLED maxi switch UV mode: 0.59 W). However, the maxi lamp only performed significantly better in exposed microhabitats, whereas the UV lamp performed similarly in the sheltered and moderately sheltered sites. The number of individuals caught in the dry grassland habitat was greater than in the orchard meadow (1288 vs. 969), whereas the number of species was similar in both habitats (120 vs. 128). Higher numbers of individuals were caught in the moderately sheltered sites than in the sheltered and exposed sites (935 vs. 773 vs. 549). The same trend was seen in the number of species (119 vs. 113 vs. 110). The communities of moths caught by traps with different lamps were similar. We conclude that light-trapping is a robust method that delivers comparable results even when different lamps are used. The use of several weak lamps is more efficient and results in larger catches than the use of a single strong lamp.

This work focuses on the optical performance of silver nanowire grids as front solar cell electrodes in a realistic dielectric environment. To do so, we first demonstrate the successful integration of the metallic grids on an ITO-free c-Si solar cell with arbitrarily high nanowires by light-induced electroplating in nano-imprinted polymer masks. The bottom-up approach enables the fabrication of high-aspect ratio grids with estimated very low sheet resistance (< 2 Ω ⋅ □) and high transparency (> 95 %). We use tunnel oxide passivating contact (TOPCon 2) silicon cells as a platform to probe the grid's transparency. External quantum efficiency maps together with optical simulations reveal that the grids' transparency in the visible spectral range is greater than expected from geometrical shading due to the sub-wavelength cross-section of the metal nanowires. On top of that, the nanowire grid even enhances the photocurrent at the near infrared, as a result of the increased optical path length from the grid's diffraction. Lastly, we demonstrate that the cell's photocurrent is unaffected by the angle of illumination up to about 40°, which is the relevant range for encapsulated cells in solar panels. Our findings highlight the dual role of metal nanowire grids as both electrical conductors and optical enhancers, offering substantial potential for future photovoltaic technologies. • Silver nanowire grids successfully integrated as transparent electrodes on ITO-free c-Si solar cells • The grids show high transparency (>95%) and low sheet resistance (< 2 Ω / □). • Diffraction from the nanowire grids enhances near-infrared light absorption. • The optical performance of silver nanowire grids is mantained for incident angles up to 40°. • Silver nanowire grids are both efficient electrical conductors and optical enhancers. • Light-induced electroplating and nanoimprint lithography has the potential to roll-to-roll production. [ABSTRACT FROM AUTHOR]

The issues related to global energy needs and environmental safeties as well as health crisis are some of the major challenges faced by the human, which make us to generate new pollution-free and sustainable energy sources. For that the optical functional nanostructures can be manipulated the confined light at the nanoscale level. These characteristics are emerging and leading candidate for the solar energy conversion. The combination of photonic (dielectric) and plasmonic (metallic) nanostructures are responsible for the development of better optical performance in solar cells. Here, the enhancement of light trapping within the thin active region is the primary goal. In this work, we have studied the influence of front-ITO (rectangular) and back-Ag (triangular) nanogratings were incorporated with ultrathin film amorphous silicon (a-Si) solar cell by using rigorous coupled wave analysis (RCWA) method. The improvement of light absorption, scattering (large angle), diffraction and field distributions (TE/TM) were demonstrated by the addition of single and dual nanogratings structures. Significantly, the plasmonic (noble metal) nanogratings are located at the bottom of the cell structure as a backside reflector which is helpful for the omni-directional reflection and increased the path length (life time) of the photons due to that the collection of the charge carriers were enhanced. Further, the proposed solar cell structure has optimized and compared to a back-Ag, front-ITO and dual nanogratings based ultrathin film amorphous silicon solar cell. Finally, the obtained results were evidenced for the assistance of photonic and plasmonic modes and achieved the highest current density (Jsc) of 23.82 mA/cm2 (TE) and 22.75 mA/cm2 (TM) with in 50 nm thin active layers by integration of (dual) cell structures. [ABSTRACT FROM AUTHOR]

By reducing the thickness of the absorber layers, ultrathin GaAs solar cells can be fabricated in a more cost‐effective manner using less source material and shorter deposition times. In this work, ultrathin GaAs solar cells are presented with a diffuse scattering layer based on wide bandgap GaP grown directly on the device layers of the cells with MOCVD. The roughness and surface morphology are quantified using atomic force microscopy and the resulting diffuse scattering capability is assessed using wavelength‐dependent reflectance measurements. Ohmic rear contacts are made using contact points etched through the GaP layer, for which an etching procedure using I2:KI was developed and optimized. The performance of the GaP textured ultrathin GaAs cells are compared with equivalent planar cells using current density‐voltage measurements and external quantum efficiency measurements, where the GaP textured cells demonstrate an increase of 6.7% in the short‐circuit current density (JSC), which was found to be as high as 21.9 mA·cm−2 as a result of increased photon absorption by light‐trapping. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have emerged in recent years as promising photovoltaic materials due to their excellent optical and electrical properties, enabling perovskite solar cells (PSCs) with certified power conversion efficiencies (PCEs) greater than 25%. Provided radiative recombination is the dominant recombination mechanism, photon recycling – the process of reabsorption (and re-emission) of photons that result from radiative recombination – can be utilized to further enhance the PCE toward the Shockley–Queisser (S-Q) theoretical limit. Geometrical optics can be exploited for the intentional trapping of such re-emitted photons within the device, to enhance the PCE. However, this scheme reaches its fundamental diffraction limits at the submicron scale. Therefore, introducing photonic nanostructures offer attractive solutions to manipulate and trap light at the nanoscale via light coupling into guided modes, as well as localized surface plasmon and surface plasmon polariton modes. This review focuses on light-trapping schemes for efficient photon recycling in PSCs. First, we summarize the working principles of photon recycling, which is followed by a review of essential requirements to make this process efficient. We then survey photon recycling in state-of-the-art PSCs and propose design strategies to invoke light-trapping to effectively exploit photon recycling in PSCs. Finally, we formulate a future outlook and discuss new research directions in the context of photon recycling.

Solar-driven interfacial evaporation technology is a novel and efficient desalination process that helps alleviate the global shortage of freshwater resources. We developed a Janus evaporator assembled from cotton hydrogel, hydrophilic polyester fabric (PF), and Hydrophobic Wood (PW). By doping graphene oxide and TiO 2 as light-absorbing materials within the hydrogel, we achieved a high absorptivity of over 90% across the entire solar spectrum. The hydrophilically modified PF, combined with the PW substrate, provided robust water transport and reduced thermal losses. Subsequent optical path simulations using TracePro74 software verified that the sawtooth light-trapping design of the wood substrate increased multiple light reflections and absorption (compared to a flat structure), enhancing light absorption capabilities. The sawtooth interface also enlarged the evaporation area, further boosting evaporation performance. The cleverly designed evaporator exhibited an evaporation rate of 1.722 kg m -2 h -1 and an efficiency of 83.1% under 1 sun irradiation. Additionally, after applying polydimethylsiloxane to the single surface of the photothermal hydrogel for low surface energy treatment, the resulting Janus structure demonstrated asymmetric wettability that prevented salt ions from accumulating on the irradiated interface. After 8 h of continuous evaporation in saline water (10 wt %), only slight salt crystallization occurred at the edges. The evaporator maintained long-term stability during a 15 day cyclic test, and the produced freshwater fully met the relevant drinking water standards. The components of the evaporator are characterized by simple fabrication, low cost, and eco-friendliness, offering significant application potential in the global context of energy conservation and emission reduction initiatives.

In this paper, we design an optical energy harvesting system composed of a magnet with a smooth surface, magnetically levitated pyrolytic graphite, and a light source. A periodic force field was constructed by modulating the light absorption of graphite at different positions through the interference of light on the smooth magnet surface and the linear variation of graphite magnetization with light absorption, thereby driving the graphite to vibrate periodically. It is confirmed in our study that this photo-magnetic effect can convert continuous light energy into vibrational kinetic energy, the driving light intensity can be reduced by 3-4 orders of magnitude and the amplitude can reach tens of microns, and the wavelength range of the driving light can cover the visible and infrared light bands, which makes it possible to develop a new type of light-driven micro-nano mechanical motor or light energy harvesting system. Graphite motion amplitude varies with light power when the magnetic field gradient is 1.1 T/m (black line) and 1.2 T/m (red line), the inset shows the schematic diagram of graphite magnetic levitation and interference light field intensity distribution diagram of light absorption and force variation. [Display omitted] • Energy Harvesting MEMS device based on continuous light-driven spontaneous vibration. • The driving light field can be as low as 0.1mw/cm2. • Wide driving wavelength range, enables the usage of the entire spectrum of sunlight. • The amplitude can reach tens of microns with high speed. [ABSTRACT FROM AUTHOR]

High-efficiency perovskite solar cells (PSCs) are one of the promising candidates to solve the energy crisis worldwide. Optical loss is one of the factors limiting the efficiency of PSCs and antireflection layers provide a dependable method for improving the efficiency of PSCs. Here, a design and optimization of PSCs with a SiO 2 @TiO 2 nanoparticles (NPs) antireflection layer is systematically studied by COMSOL Multiphysics. The effect of different shell-thickness ratios (STRs) on the average light absorption and short-circuit current density of PSCs is simulated and compared with that of planar PSCs. The results show that the average light absorption of PSCs with SiO 2 @TiO 2 NPs of 0.08 STR is 83.21%, which is 5.17% higher than that of PSCs with SiO 2 NPs and 10.11% higher than that of planar PSCs. Our results provide theoretical guidance for using SiO 2 @TiO 2 NPs as antireflection layers in the fabrication of PSCs. • A relative improvement of 8.81% in PCE of perovskite solar cell was achieved by effective photon management. • The photon management was achieved by combining SiO 2 @TiO 2 core-shell nanostructures antireflection layer. • The photon management realized antireflection with a gradient refractive index, meanwhile improved light-trapping ability. [ABSTRACT FROM AUTHOR]

One of the most promising desalination techniques is photothermal membrane distillation (PhMD). The research focus of PhMD technology is material renewal and structural design. Herein, the CuMOF-PVDF photothermal membranes were designed for PhMD. Firstly, a combination of chemical plating and oxidation was used to generate Cu(OH) 2 nanowires (NWs) onto the PVDF membrane. Then, the ligands were chemically bonded with Cu(OH) 2 NWs to grow the photothermal layer formed by the CuMOF hierarchical structure (CMHS). Under sunlight irradiation, the light was trapped in the CMHS, amplifying absorption and conversion of light. The CuMOF-PVDF membrane with the match-like CMHS absorbed 88.6 % of the light, resulting in a surface temperature of 74.3 °C after 600s. Moreover, by reducing the evaporation enthalpy of water, the performance of the CuMOF photothermal layer was comprehensively improved, realizing a water evaporation rate of 1.55 kg‧m−2‧h−1 and a high photothermal conversion rate of 71.4 %. During the PVMD process, the feed solution in the CuMOF photothermal layer was fully heated and supplied to the vaporization area, weakening the temperature polarization. Consequently, the flux of the CuMOF-PVDF membrane was 3.07 kg‧m−2‧h−1 and a 99.9 % rejection rate, corresponding to an energy efficiency of 85.2 %. The CuMOF-PVDF membrane is an efficient tool for PhMD, helping to advance desalination technologies. [Display omitted] • Photothermal membrane consists of CuMOF photothermal layer and PVDF membrane. • Photothermal layer has hierarchical structure, shaping like a match. • Contribution of hierarchical structure to overall performance of membrane. • CuMOF-PVDF membranes perform well in photothermal vacuum membrane distillation. [ABSTRACT FROM AUTHOR]

Efficient light absorption and trapping are of vital importance for the solar water evaporation by hydrogel-based photothermal conversion materials. Conventional strategies are focused on the development of the composition and structure of the hydrogel's internal network. In our point of view, the importance of the surface structure of hydrogel has usually been underestimated or ignored. Here inspired by the excellent absorbance and water transportation ability of biological surface structure, the hierarchical structured hydrogel evaporators (HSEs) increased the light absorption, trapping, water transportation and water-air interface, which is the beneficial photothermal conversion and water evaporation. The HSEs showed a rapid evaporation rate of 1.77 kg·m-2·h-1 at about 92% energy efficiency under one sun (1 kW·m-2). Furthermore, the superhydrophilic window device was used in this work to collect the condensed water, which avoids the light-blocking caused by the water mist formed by the small droplets and the problem of the droplets stick on the device dropping back to the bulk water. Integrated with the excellent photothermal conversion hydrogel and superhydrophilic window equipment, this work provides efficient evaporation and desalination of hydrogel-based solar evaporators in practical large-scale applications. [ABSTRACT FROM AUTHOR]

Controllable large-scale integration of two-dimensional (2D) materials with organic semiconductors and the realization of strong coupling between them still remain challenging. Herein, we demonstrate a wafer-scale, vertically layered SnSe 2 /PTAA heterojunction array with high light-trapping ability via a low-temperature molecular beam epitaxy method and a facile spin-coating process. Conductive probe atomic force microscopy (CP-AFM) measurements reveal strong rectification and photoresponse behavior in the individual SnSe 2 nanosheet/PTAA heterojunction. Theoretical analysis demonstrates that vertically layered SnSe 2 /PTAA heterojunctions exhibit stronger C-Se covalent coupling than that of the conventional tiled type, which could facilitate more efficient charge transfer. Benefiting from these advantages, the SnSe 2 /PTAA heterojunction photodetectors with an optimized PTAA concentration show high performance, including a responsivity of 41.02 A/W, an external quantum efficiency of 1.31 × 10 4 %, and high uniformity. The proposed approach for constructing large-scale 2D inorganic-organic heterostructures represents an effective route to fabricate high-performance broadband photodetectors for integrated optoelectronic systems.

• A motheye-structured photoanode for water splitting was designed and fabricated. • The motheye-patterned gap-plasmon structure maximized solar absorption. • A current density of 1.48 mA/cm2 was obtained with a thin layer of BiVO4 (200 nm). Bismuth vanadate (BiVO 4) is one of the most promising materials used in photoelectrochemical cells (PEC cells), which are significant generators of clean energy. As with many promising materials used as photoanodes, the main problem limiting the efficiency of BiVO 4 -based photoanodes is the trade-off between their large light penetration depth and small diffusion length. To reduce this gap, various methods have been investigated to improve the absorption efficiency of ultra-thin BiVO 4 layers, including template-assisted nanostructuring. In this study, we have implemented a densely packed sub-wavelength-scale nanocone array inspired by the motheye morphology using a direct printing method. Subsequently, we fabricated a series of triple-deck hierarchical photoanodes using a motheye template via the successive deposition of Au, SnO 2 , and BiVO 4. The fabricated motheye structures exhibit a gradual change in their refractive index, which is excellent for reducing the reflection of high refractive index materials. In addition, the synergy between the light trapping effects of the nanocone array and gap-plasmon structure (reflector/spacer/antenna) maximizes the absorption of incident solar light. Due to this enhancement, a current density of 1.48 mA/cm2 was obtained using a thin layer of BiVO 4 (200 nm) at 1.23 V vs. RHE under a simulated solar light (AM 1.5G). Our results can be applied toward many promising candidate materials used for photoanode and optoelectronic devices, where poor electronic properties and high reflectivity limit the absorption and power generation efficiencies. [ABSTRACT FROM AUTHOR]

• A metal-oxide pyramid texture is converted into the non-resonant optical metasurfaces. • Metasurfaces are realized through the templated growth electrodeposition of nanowires. • A J SC gain of 10-25% is achieved as compared to the planar device. • Energy conversion efficiencies of perovskite/perovskite TSCs can reach over 30%. • Optics of solar cells is investigated by FDTD optical simulations. The short-circuit current density and energy conversion efficiency of single-junction perovskite and perovskite/perovskite tandem solar cells can be increased by photon management. In this study, optical metasurfaces were investigated as potential light trapping structures oppose to commonly used pyramidal surface textures. Herein, metal oxide-based non-resonant metasurfaces were investigated as potential light-trapping structures in perovskite solar cells. The zinc oxide nanowire-based building blocks of the metasurface can be prepared by a templated electrodeposition through a mask of resist. The phase of the incident light can be controlled by the edge length of the subwavelength large zinc oxide nanowires. An array of zinc oxide nanowires was prepared and characterized in the current study. Three-dimensional (3D) finite-difference time-domain (FDTD) optical simulations were used to compare solar cells covered with non-resonant metasurfaces with commonly used light trapping structures. As compared to the solar cells covered with zinc oxide pyramid surface texture, solar cells with the integrated non-resonant metasurfaces exhibit almost identical quantum efficiencies and short-circuit current densities. Investigations of such metasurfaces will not only improve the photon absorption in perovskite solar cells but also reveal a pathway to make high-efficiency next-generation solar cells. Detailed guidelines for the realization of non-resonant metal oxide metasurfaces will be provided. [ABSTRACT FROM AUTHOR]

Background The biodiversity of West and Central Africa is understudied, including butterflies and moths (Lepidoptera). Cameroon, through its position in between few biogeographic regions and diversity of habitats, is an important hotspot of lepidopteran diversity. However, the country also ranks low when it comes to local biodiversity knowledge. During our long-term ecological projects in the Cameroonian part of the Gulf of Guinea Highlands, we collected rich material of butterflies and moths, including a number of interesting faunistic records. New information In this study, we report 31 species of butterflies and moths which have not yet been recorded in Cameroon. These species comprised eight new genera records for the country. In many cases, our records represented an important extension of the species' known distribution, including ten species whose distribution ranges extended into the Guinean biogeographic region. We also comment on the species' elevational distribution ranges on Mount Cameroon where most of our records originated. Additionally, we confirm the presence of a butterfly Telchinia encedena, after more than a century since its first and so far its only record in Cameroon. [ABSTRACT FROM AUTHOR]

Zinc oxide nanorod arrays (ZnO NRAs) have been previously introduced as electron transport layer (ETL) of perovskite solar cells (PSCs) due to their high electron mobility and unique textured morphology. However, the presence of hydroxyl and oxygen vacancies on the surface of bare intrinsic ZnO NRAs may act as defect centers leading to carrier nonradiative recombination and the device photovoltaic performance degradation. Here, we propose a mutilayer SnO 2 /Al-doped ZnO nanorod arrays/SnO 2 (SnO 2 /AZO NRAs/SnO 2) composite to be utilized as ETL of all-inorganic CsPbBr 3 PSCs. The influence of AZO NRAs with various Al ion (Al3+) doping content on the performance of CsPbBr 3 PSCs was explored. The hole-free carbon-based CsPbBr 3 PSCs with an architecture of FTO/SnO 2 /AZO NRAs/SnO 2 /CsPbBr 3 /carbon based on 1 at% AZO NRAs exhibited the best photovoltaic performance with a champion power conversion efficiency (PCE) of 7.11 %, open-circuit voltage (V oc) of 1.46 V, short-circuit current density (J sc) of 6.88 mA/cm2, and fill factor (FF) of 71.1 %, compared with the bare intrinsic ZnO-based counterpart with a PCE of 3.45 %, V oc of 0.80 V, J sc of 8.46 mA/cm2, and FF of 51 %, respectively. The photovoltaic performance enhancement can be atrributed to enhanced light collection and electron extraction capability, with lower open-circuit voltage loss and more suitable interface band alighment. It is notable that the AZO NRAs were prepared by a facile electrodeposition approach to obtain large-area textured ETLs. This strategy may also be applicable to the photovoltaic performance improvemet of all types of PSCs. [ABSTRACT FROM AUTHOR]

The pursuit of ever-more efficient, reliable, and affordable solar cells has pushed the development of nano/micro-technological solutions capable of boosting photovoltaic (PV) performance without significantly increasing costs. One of the most relevant solutions is based on light management via photonic wavelength-sized structures, as these enable pronounced efficiency improvements by reducing reflection and by trapping the light inside the devices. Furthermore, optimized microstructured coatings allow self-cleaning functionality via effective water repulsion, which reduces the accumulation of dust and particles that cause shading. Nevertheless, when it comes to market deployment, nano/micro-patterning strategies can only find application in the PV industry if their integration does not require high additional costs or delays in high-throughput solar cell manufacturing. As such, colloidal lithography (CL) is considered the preferential structuring method for PV, as it is an inexpensive and highly scalable soft-patterning technique allowing nanoscopic precision over indefinitely large areas. Tuning specific parameters, such as the size of colloids, shape, monodispersity, and final arrangement, CL enables the production of various templates/masks for different purposes and applications. This review intends to compile several recent high-profile works on this subject and how they can influence the future of solar electricity.

Featured Application: Light management is important for solar cell performance. Light-coupling and light-scattering based on rough interfaces are discussed in detail for the example application in silicon thin-film solar cells. The findings are relevant for many photovoltaic technologies. Increasing the efficiency of solar cells relies on light management. This becomes increasingly important for thin-film technologies, but it is also relevant for poorly absorbing semiconductors like silicon. Exemplarily, the performance of a-Si:H/µc-Si:H tandem solar cells strongly depends on the texture of the front and rear contact surfaces. The rear contact interface texture usually results from the front surface texture and the subsequent absorber growth. A well-textured front contact facilitates light-coupling to the solar cell and light-trapping within the device. A variety of differently textured ZnO:Al front contacts were sputter deposited and subsequently texture etched. The optical performance of a-Si:H/µc-Si:H tandem solar cells were evaluated regarding the two effects: light-coupling and light-trapping. A connection between the front contact texture and the two optical effects is demonstrated, specifically, it is shown that both are induced by different texture properties. These findings can be transferred to any solar cell technologies, like copper indium gallium selenide (CIGS) or perovskites, where light management and modifications of surface textures by subsequent film growth have to be considered. A modulated surface texture of the ZnO:Al front contact was realized using two etching steps. Improved light-coupling and light-trapping in silicon thin-film solar cells lead to 12.5% efficiency. [ABSTRACT FROM AUTHOR]

Abstract The optical constants of many metals commonly used in solar cells, e.g. as contacts, rear side planar reflectors, or more complex nanopatterned light-trapping structures, can vary depending on deposition method, thickness and other factors, and as such are not documented consistently in the literature. In the case of nanometallic light-trapping structures specifically designed to improve absorption in a solar cell, the choice of optical constants used in simulations significantly affects the predicted enhancement, as well as the structure's optimal dimensions. The trade-off between coupling into guided modes in the photovoltaic material and the number of photons absorbed parasitically in the metal leads to small differences in the optical constants giving significantly different results for the quantum efficiency and photogenerated current. This work documents several optical constant sources for silver, aluminium, gold and titanium, and the effect this has on plasmon quality factors. The effect of choosing different optical constant sources on modelling outcomes is quantified by considering the optimization of a test structure comprising a grid of metal nanodisks on the front surface of a thinned-down GaAs cell. Finally, we define a new spectrally-integrated figure of merit for comparing the expected performance of metals in light-trapping structures based on their optical constants, which we name the spectral absorption enhancement factor (SAEF). Highlights • The reported optical constants of metals vary due to deposition conditions and measurement factors. • Optimization of nanometallic light-trapping structures is significantly affected by the choice of optical constants. • Predicted solar cell performance varies significantly depending on the optical constants used. • The performance of a metal for absorption enhancement can be predicted from its optical constants. [ABSTRACT FROM AUTHOR]

Quantitative community-wide moth surveys frequently employ flight-interception traps equipped with UV-light emitting sources as attractants. It has long been known that moth species differ in their responsiveness to light traps. We studied how the settling behaviour of moths at a light trap may further contribute to sampling bias. We observed the behaviour of 1426 moths at a light tower. Moths were classified as either, settling and remaining still after arrival, or continually moving on the gauze for extended periods of time. Moths that did not move after settling may not end up in the sampling container of the light trap and therefore are under-represented in automated trap samples relative to their true proportions in the community. Our analyses revealed highly significant behavioural differences between moths that differed in body size. Small moths were more likely to remain stationary after settling. As a corollary, representatives of three taxa, which in Europe are predominantly small species (Nolidae, Geometridae: Eupitheciini, Erebidae: Lithosiini), usually settled down immediately, whereas most other moths remained active on or flying around the trap for some time. Moth behaviour was also modulated by ambient temperature. At high temperatures, they were less likely to settle down immediately, but this behavioural difference was most strongly apparent among medium-sized moths. These results indicate the likely extent of the sampling bias when analysing and interpreting automated light-trap samples. Furthermore, to control for temperature modulated sampling bias temperature should always be recorded when sampling moths using flight-interception traps.

We study experimentally and with wave optics modelling the absorption of light in CsPbBr 3 perovskite nanowire arrays fabricated into periodic pores of an anodized aluminum oxide matrix, for nanowire diameters from 30 to 360 nm. First, we find that all the light that couples into the array can be absorbed by the nanowires at sufficient nanowire length. This behavior is in strong contrast to the expectation from a ray-optics description of light where, for normally incident light, only the rays that hit the cross-section of the nanowires can be absorbed. In that case, the absorption in the sample would be limited to the area fill factor of nanowires in the hexagonal array, which ranges from 13% to 58% for the samples that we study. Second, we find that the absorption saturates already at a nanowire length of 1000-2000 nm, making these perovskite nanowires promising for absorption-based applications such as solar cells and photodetectors. The absorption shows a strong diameter dependence, but for all diameters the transmission is less than 24% already at a nanowire length of 500 nm. For some diameters, the absorption exceeds that of a calculated thin film with 100% coverage. Our analysis indicates that the strong absorption in these nanowires originates from light-trapping induced by the out-of-plane disorder due to random axial position of each nanowire within its pore in the matrix., (Creative Commons Attribution license.)

Abstract This paper presents investigation on the effects of etching time towards broadband absorption enhancement in black silicon (b-Si) fabricated by silver-assisted chemical etching. The c-Si wafers are deposited with a thin silver (Ag) layer and annealed in a nitrogen (N 2) atmosphere to form Ag nanoparticles (Ag NPs). The wafers are then etched in an aqueous solution of HF:H 2 O 2 :H 2 O at room temperature at different etching times to form the b-Si. All the b-Si wafers show rough surface morphology due to the presence of nanotextures. The b-Si exhibit wafers exhibit significantly lower broadband reflection compared to a planar c-Si reference. The c-Si wafer etched for 70 s demonstrates the lowest broadband reflection, with reflection of 3% at wavelength of 600 nm (i.e. absorption of 97%). This sample exhibits b-Si nanotextures with width of 50–100 nm and height of 300–400 nm. The enhanced broadband light absorption in the b-Si leads to maximum potential short-circuit current density (J sc (max)) of 39.7 mA/cm2, or 51% enhancement compared to a planar c-Si reference, calculated for wavelength region of 300–1100 nm. [ABSTRACT FROM AUTHOR]

The effect of thickness deviation on the optical properties of graphene-based optical microstructure was studied by using the transfer matrix method. Machining errors led to inconsistencies in the thicknesses of different parts and resulted in an offset of absorption peak, thus significantly reducing the average light absorption. The 3-nm deviation decreased the light absorption of graphene-optical microstructure by approximately 3.5 times. However, if the machining error is included in the design, then a relatively small Q value will help reduce the effect of machining error and the light absorption can be enhanced by about 32%. [ABSTRACT FROM AUTHOR]

We report thin-film InAs/GaAs quantum dot (QD) solar cells with n − i − p + deep junction structure and planar back reflector fabricated by epitaxial lift-off (ELO) of full 3-in wafers. External quantum efficiency measurements demonstrate twofold enhancement of the QD photocurrent in the ELO QD cell compared to the wafer-based QD cell. In the GaAs wavelength range, the ELO QD cell perfectly preserves the current collection efficiency of the baseline single-junction ELO cell. We demonstrate by full-wave optical simulations that integrating a micro-patterned diffraction grating in the ELO cell rearside provides more than tenfold enhancement of the near-infrared light harvesting by QDs. Experimental results are thoroughly discussed with the help of physics-based simulations to single out the impact of QD dynamics and defects on the cell photovoltaic behavior. It is demonstrated that non radiative recombination in the QD stack is the bottleneck for the open circuit voltage ( V oc ) of the reported devices. More important, our theoretical calculations demonstrate that the V oc offset of 0.3 V from the QD ground state identified by Tanabe et al., 2012, from a collection of experimental data of high quality III-V QD solar cells is a reliable – albeit conservative – metric to gauge the attainable V oc and to quantify the scope for improvement by reducing non radiative recombination. Provided that material quality issues are solved, we demonstrate – by transport and rigorous electromagnetic simulations – that light-trapping enhanced thin-film cells with twenty InAs/GaAs QD layers reach efficiency higher than 28% under unconcentrated light, ambient temperature. If photon recycling can be fully exploited, 30% efficiency is deemed to be feasible. [ABSTRACT FROM AUTHOR]

In this paper, novel micro- and nano-composite Al-doped ZnO (AZO) films with broadband-gap light-trapping capacity was successfully fabricated by post-chemical-etching AZO film and re-sputtering self-textured H and Al co-doped ZnO (HAZO) film. The influence of pressure and etching time on the optical and electrical properties of HAZO, AZO, and AZO/HAZO films were systematically investigated. The performance of this novel ZnO film was increased remarkably compared to that of the post-etched AZO film or native textured HAZO film for both long and short wavelengths. Microcrystalline silicon solar cells deposited on this new type of AZO/HAZO films exhibited a strong enhancement of 13.4% in the conversion efficiency, demonstrating its wide application prospect. [ABSTRACT FROM AUTHOR]

This paper presents optimisation of rear Si texturing by KOH-based solution for enhanced light-trapping in liquid-phase crystallised Si thin-film solar cells on glass. Texturing with 3 µm Si removal exhibits the largest absorption enhancement (compared with 1 and 2 µm Si removal) due to the enhanced light scattering by the rear pyramidal features. In the solar cells with SiO x /SiN x /SiO x buffer layer (with anti-reflection effect), the J sc is found to increase from 20.4 (planar reference) to 22.6 mA/cm 2 (10.8% enhancement) with the optimised rear Si texturing. The V oc and pFF are not degraded. After incorporating white paint back surface reflector and front anti-reflection foil to the rear-textured solar cells, J sc up to 25.4 mA/cm 2 (24.5% relative enhancement) is achieved. [ABSTRACT FROM AUTHOR]

The modification of the steep and sharp valleys on the surface of the boron-doped zinc oxide (BZO) front electrodes by plasma surface treatment is a critical process for avoiding a significant reduction in the electrical performance of thin-film silicon solar cells. In this work, we report the origin of the changes in the electrical and optical properties of the BZO films that occur after this process. On the basis of an analysis of the chemical states, we found an improvement of the carrier concentration along with the treatment time that was mainly due to an increase of the oxygen vacancy. This indicated a deficiency of the oxygen in the BZO films under argon-ion bombardment. The red-shift of the A 1 longitudinal optical mode frequency in the Raman spectra that was attributed to the existence of vacancy point defects within the films also strengthened this argument. The significant reduction of the haze ratio as well as the appearance of interference peaks on the transmittance spectra as the treatment time was increased were mainly due to the smoothing of the film surface, which indicated a degradation of the light-scattering capability of the BZO films. We also observed a gain of the visible-region transmittance that was attributed to the decrease of the thickness of the BZO films after the plasma surface treatment, instead of the crystallinity improvement. On the basis of our findings, we have proposed a further design rule of the BZO front electrodes for thin-film silicon solar cell applications. [ABSTRACT FROM AUTHOR]

Increasing the efficiency of solar cells relies on light management. This becomes increasingly important for thin-film technologies, but it is also relevant for poorly absorbing semiconductors like silicon. Exemplarily, the performance of a-Si:H/µc-Si:H tandem solar cells strongly depends on the texture of the front and rear contact surfaces. The rear contact interface texture usually results from the front surface texture and the subsequent absorber growth. A well-textured front contact facilitates light-coupling to the solar cell and light-trapping within the device. A variety of differently textured ZnO:Al front contacts were sputter deposited and subsequently texture etched. The optical performance of a-Si:H/µc-Si:H tandem solar cells were evaluated regarding the two effects: light-coupling and light-trapping. A connection between the front contact texture and the two optical effects is demonstrated, specifically, it is shown that both are induced by different texture properties. These findings can be transferred to any solar cell technologies, like copper indium gallium selenide (CIGS) or perovskites, where light management and modifications of surface textures by subsequent film growth have to be considered. A modulated surface texture of the ZnO:Al front contact was realized using two etching steps. Improved light-coupling and light-trapping in silicon thin-film solar cells lead to 12.5% efficiency.

One of the foremost challenges in designing thin-film silicon solar cells (TFSC) is devising efficient light-trapping schemes due to the short optical path length imposed by the thin absorber thickness. The strategy relies on a combination of a high-performance back reflector and an optimized texture surface, which are commonly used to reflect and scatter light effectively within the absorption layer, respectively. In this paper, highly promising light-trapping structures based on a photonic crystal (PC) for TFSCs were investigated via simulation and experiment. Firstly, a highly-reflective one-dimensional photonic crystal (1D-PC) was designed and fabricated. Then, two types of 1D-PC-based back reflectors (BRs) were proposed: Flat 1D-PC with random-textured aluminum-doped zinc oxide (AZO) or random-textured 1D-PC with AZO. These two newly-designed BRs demonstrated not only high reflectivity and sufficient conductivity, but also a strong light scattering property, which made them efficient candidates as the electrical contact and back reflector since the intrinsic losses due to the surface plasmon modes of the rough metal BRs can be avoided. Secondly, conical two-dimensional photonic crystal (2D-PC)-based BRs were investigated and optimized for amorphous a-SiGe:H solar cells. The maximal absorption value can be obtained with an aspect ratio of 1/2 and a period of 0.75 μm. To improve the full-spectral optical properties of solar cells, a periodically-modulated PC back reflector was proposed and experimentally demonstrated in the a-SiGe:H solar cell. This periodically-modulated PC back reflector, also called the quasi-crystal structure (QCS), consists of a large periodic conical PC and a randomly-textured Ag layer with a feature size of 500-1000 nm. The large periodic conical PC enables conformal growth of the layer, while the small feature size of Ag can further enhance the light scattering. In summary, a comprehensive study of the design, simulation and fabrication of 1D-PC- and 2D-PC-based back reflectors for TFSCs was carried out. Total absorption and device performance enhancement were achieved with the novel PC light-trapping systems because of their high reflectivity or high scattering property. Further research is necessary to illuminate the optimal structure design of PC-based back reflectors and high solar cell efficiency. [ABSTRACT FROM AUTHOR]

Plasmonics is a new promising approach to enhance the light absorption in the thin film solar cells. The plasmonic effects of the metal nanoparticle introduced in thin film solar cells could also be detrimental for the higher optical absorption and hence the higher efficiency of solar cells. The effects of the Ag nanospheres arrays on the absorption of amorphous silicon solar cells were investigated by a numerical simulation based on the finite element method. The light absorption under different radius and width of the grating has been calculated. The optimization results show that the absorption of the solar cell with Ag nanospheres is enhanced up to 64 % under AM1.5 illumination in the 500-730 nm wavelength range compared with the reference cell. The physical mechanisms of absorption enhancement in different wavelength range have been discussed. These results are promising for the design of amorphous silicon thin film solar cells with enhanced performance. [ABSTRACT FROM AUTHOR]

This paper presents enhanced light-trapping (LT) in liquid-phase crystallised silicon (LPC Si) thin-film solar cells on glass superstrate by optimised back surface reflectors (BSRs). In the LPC Si film on SiO x buffer layer (without anti-reflection effect), the white paint BSR is found to increase the long wavelengths light absorption, with potential short-circuit current density (J sc ) of 23.6 mA/cm 2 (15.7% enhancement, compared to the planar reference film). Ag plasmonic nanoparticles (NPs) reflector with surface coverage of 47.9% and average diameter of 196.3 nm shows almost similar absorption enhancement as the white paint but with slightly lower potential J sc (23.3 mA/cm 2 , or 14.2% enhancement). In the LPC Si solar cells, the average open-circuit voltage (V oc ) and pseudo fill factor (pFF) are not deteriorated by the presence of the Ag NPs on the Si surface. When combining the Ag NPs, white paint and anti-reflection foil, J sc up to 23.3 mA/cm 2 (18.9% enhancement compared to the planar reference cell) is achieved. [ABSTRACT FROM AUTHOR]

We achieved an inverted pyramid structure, meeting the tradeoff between the light reflection minimization and carrier recombination by adjusting the one-step Cu-assisted texturization of silicon wafer, and silicon solar cells based on this structure were fabricated, which gained a high conversion efficiency of 18.87% without using any complex techniques. These data were compared with the performance of conventional upright pyramid silicon solar cells as manufactured using identical raw wafers, the Cu-etched inverted pyramid silicon cells collected 0.59 mA/cm 2 more short-circuit current density and 0.47% more efficiency. Importantly, our data demonstrate the better performance and manufacturability of inverted pyramid structured silicon solar cell and as such may open new perspectives for high efficiency solar cell applications. [ABSTRACT FROM AUTHOR]