The Transfer Matrix Method (TMM) has become a prominent tool for the optical simulation of thin−film solar cells, particularly among researchers specializing in organic semiconductors and perovskite ...materials. As the commercial viability of these solar cells continues to advance, driven by rapid developments in materials and production processes, the importance of optical simulation has grown significantly. By leveraging optical simulation, researchers can gain profound insights into photovoltaic phenomena, empowering the implementation of device optimization strategies to achieve enhanced performance. However, existing TMM−based packages exhibit limitations, such as requiring programming expertise, licensing fees, or lack of support for bilayer device simulation. In response to these gaps and challenges, we present the TMM Simulator (TMM−Sim), an intuitive and user−friendly tool to calculate essential photovoltaic parameters, including the optical electric field profile, exciton generation profile, fraction of light absorbed per layer, photocurrent, external quantum efficiency, internal quantum efficiency, and parasitic losses. An additional advantage of TMM−Sim lies in its capacity to generate outcomes suitable as input parameters for electro−optical device simulations. In this work, we offer a comprehensive guide, outlining a step−by−step process to use TMM−Sim, and provide a thorough analysis of the results. TMM−Sim is freely available, accessible through our web server (nanocalc.org), or downloadable from the TMM−Sim repository (for Unix, Windows, and macOS) on GitHub. With its user−friendly interface and powerful capabilities, TMM−Sim aims to facilitate and accelerate research in thin−film solar cells, fostering advancements in renewable energy technologies.
•Intuitive and user-friendly tool for optical simulation of essential photovoltaic parameters.•Ability to simulate two device architectures: bilayer and bulk heterojunction.•Possibility of calculating the photocurrent as a function of the active layer thickness for device optimization.•The software is freely available for use either through a dedicated web server or by downloading the binary files.
Passive daytime radiative cooling (PDRC) has drawn significant attention recently for electricity-free cooling. Porous polymers are attractive for PDRC since they have excellent performance and ...scalability. A fundamental question remaining is how PDRC performance depends on pore properties (e.g., radius, porosity), which is critical to guiding future structure designs. In this work, optical simulations are carried out to answer this question, and effects of pore size, porosity, and thickness are studied. We find that mixed nanopores (e.g., radii of 100 and 200 nm) have a much higher solar reflectance R̅ solar (0.951) than the single-sized pores (0.811) at a thickness of 300 μm. With an Al substrate underneath, R̅ solar, thermal emittance ε̅LWIR, and net cooling power P cool reach 0.980, 0.984, and 72 W/m2, respectively, under a semihumid atmospheric condition. These simulation results provide a guide for designing high-performance porous coating for PDRC applications.
Radiative cooling is a promising passive cooling technology that reflects sunlight and emits heat to deep space without any energy consumption. Current research mainly focuses on cooling ...non‐heat‐generating objects (e.g., water) to a deep subambient temperature under sunlight. Toward real‐world applications, however, cooling outdoor objects that generate tremendous heat and have a temperature higher than ambient (e.g., communication base stations and data centres) remains a challenge. Herein, a scalable photonic film is prepared by introducing 2D dielectric nanoplates with high backward scattering efficiency into a polymer using a simulation aided thermo‐optical design. It is demonstrated that the dielectric nanoplates can break the trade‐off between optical reflection and thermal dissipation of conventional radiative coolers. The photonic film exhibits superior solar reflectance (98%) and has a stronger heat dissipation ability compared to the matrix. It exhibits ≈4 °C subambient cooling performance under direct sunlight and ≈9 °C cooling performance at night. Moreover, it also demonstrates remarkable above‐ambient cooling performance by reducing the underlying heater temperature of ≈18 °C in comparison with traditional polymers under sunlight. The dielectric nanoplates reported here provide an innovative strategy for applications related to light management beyond subambient and above‐ambient radiative cooling.
A thermo‐optically designed photonic film, which accounts for both subambient and above‐ambient radiative cooling is prepared. It consists of a visibly transparent polymer encapsulating 2D dielectric nanoplates. The nanoplates substantially improve all the advantageous properties of the photonic film that endow it with a record high solar reflectance (98%), a strong thermal emittance (90%), and an unprecedented heat dissipation ability.
A universal strategy for efficient light trapping through the incorporation of gold nanorods on the electron transport layer (rear) of organic photovoltaic devices is demonstrated. Utilizing the ...photons that are transmitted through the active layer of a bulk heterojunction photovoltaic device and would otherwise be lost, a significant enhancement in power conversion efficiency (PCE) of polyN‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole):phenyl‐C71‐butyric acid methyl ester (PCDTBT:PC71BM) and poly4,8‐bis(2‐ethylhexyl)oxybenzo1,2‐b:4,5‐b′dithiophene‐2,6‐diyl3‐fluoro‐2‐(2‐ethylhexyl)carbonylthieno3,4‐b thiophenediyl (PTB7):PC71BM by ≈13% and ≈8%, respectively. PCEs over 8% are reported for devices based on the PTB7:PC71BM blend. A comprehensive optical and electrical characterization of our devices to clarify the influence of gold nanorods on exciton generation, dissociation, charge recombination, and transport inside the thin film devices is performed. By correlating the experimental data with detailed numerical simulations, the near‐field and far‐field scattering effects are separated of gold nanorods (Au NRs), and confidently attribute part of the performance enhancement to the enhanced absorption caused by backscattering. While, a secondary contribution from the Au NRs that partially protrude inside the active layer and exhibit strong near‐fields due to localized surface plasmon resonance effects is also observed but is minor in magnitude. Furthermore, another important contribution to the enhanced performance is electrical in nature and comes from the increased charge collection probability.
High efficiency organic photovoltaic (OPV) devices are fabricated based a novel and universal light trapping mechanism, using gold nanorods (Au NRs) as back contact reflectors. The incorporation of Au NRs inside the back contact interfacial layer (titanium sub oxide) gives rise to a device efficiency of ≈13%, compared to the record performance of 8.25%. This is revealed to be mainly due to scattering by a combination of theoretical and experimental results.
In this letter, we apply an optical setup to simulate the coherent evolution of an atomic wavepacket under the action of a standing-wave optical pulse sequence. Predicted population oscillations in ...J. Opt. Soc. Am. B 39, 3012 (2022) have been observed, and the beam divergence angle, which corresponds to the atomic momentum width, has been obtained by fitting the data. Consequently, we confirm the viability of employing standing-wave optical pulse sequences for measuring the ultra-narrow momentum distribution of atoms. In addition, we introduce a fitting method suitable for data obtained under non-ideal experimental conditions, which serves as a reference for similar experiments in atomic ultra-low temperature measurements.
•We confirm the viability of employing atom interferometry to measure the temperature of ultracold atoms.•We develop a fitting method for the data obtained under non-ideal conditions.•It provides a sensitive method for measuring the divergence angle of Gaussian beams.
•The main limitation of CPV systems is related to the use of heavy solar trackers.•Integrating tracking within the CPV system is one of the possible solutions.•This work studies two concentrations, ...determining their impact on the performance.•Optical simulations and indoor measurements of the two systems are carried out.•Results show an optical efficiency above 80% and 70% for each concentration at ± 50°.
Tracking-integrated Concentrator Photovoltaics (CPV) represents an alternative to conventional CPV. The elimination of expensive and heavy solar trackers contributes to reduce the cost of conventional CPV, and open new market segments. This technology, still under development, needs further investigation. In this work, two tracking-integrated focusing systems with two different concentration levels, consisting of a fixed bi-convex aspheric lens and a movable triple-junction solar cell, are analysed. Initially, by means of detailed optical modelling, the concentrator elements are optimized. After that, they are experimentally investigated at Concentration Standard Test Conditions (CSTC) by varying the angle of incidence ± 50°. The results show an optical efficiency > 80% and > 60% for a geometric concentration of 10.0x and 82.5x, respectively, within the whole angular range. These systems could contribute to novel CPV applications such as agrivoltaics or building integrated.
Microneedles (MNs) are an emerging technology in pharmaceutics and biomedicine, and are ready to be commercialized in the world market. However, solid microneedles only allow small doses and ...time-limited administration rates. Moreover, some well-known and already approved drugs need to be re-formulated when supplied by MNs. Instead, hollow microneedles (HMNs) allow for rapid, painless self-administrable microinjection of drugs in their standard formulation. Furthermore, body fluids can be easily extracted for analysis by a reverse use of HMNs, thus making them perfect for sensing issues and theranostics applications. The fabrication of HMNs usually requires several many-step processes, increasing the costs and consequently decreasing the commercial interest. Photolithography is a well-known fabrication technique in microelectronics and microfluidics that fabricates MNs. In this paper, authors show a proof of concept of a patented, easy and one-shot fabrication of two kinds of HMNs: (1) Symmetric HMNs with a "volcano" shape, made by using a photolithographic mask with an array of transparent symmetric rings; and (2) asymmetric HMNs with an oblique aperture, like standard hypodermic steel needles, made by using an array of transparent asymmetric rings, defined by two circles, which centers are slightly mismatched. Simulation of light propagation, fabrication process, and preliminary results on ink microinjection are presented.
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