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Cu(In,Ga)Se 2 -based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Se 2 solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Se 2 does not depend on the Cu content in the explored composition range, while the absorption coefficient value is primarily determined by the Cu content. An expression for the absorption spectrum is proposed, with Ga and Cu compositions as parameters. This set of parameters allows accurate device simulations to understand remaining absorption and carrier collection losses and develop strategies to improve performances.

In the context of simulating precision laser interferometers, we use several examples to compare two wavefront decomposition methods—the Mode Expansion Method (MEM) and the Gaussian Beam Decomposition (GBD) method—for their precision and applicability. To assess the performance of these methods, we define different types of errors and study their properties. We specify how the two methods can be fairly compared and based on that, compare the quality of the MEM and GBD through several examples. Here, we test cases for which analytic results are available, i.e., non-clipped circular and general astigmatic Gaussian beams, as well as clipped circular Gaussian beams, in the near, far, and extremely far fields of millions of kilometers occurring in space-gravitational wave detectors. Additionally, we compare the methods for aberrated wavefronts and their interaction with optical components by testing reflections from differently curved mirrors. We find that both methods can generally be used for decomposing non-Gaussian beams. However, which method is more accurate depends on the optical system and simulation settings. In the given examples, the MEM more accurately describes non-clipped Gaussian beams, whereas for clipped Gaussian beams and the interaction with surfaces, the GBD is more precise.

Space-based gravitational wave detection imposes extremely high requirements on displacement measurement accuracy, with its core measurement components being laser interferometers and inertial sensors. The laser interferometers detect gravitational wave signals by measuring the distance between two test masses (TMs) housed within the inertial sensors. Spatial alignment errors of the TMs relative to the laser interferometers can severely degrade the interferometric performance, primarily by significantly amplifying tilt-to-length (TTL) coupling noise and reducing interferometric efficiency. This paper presents a systematic analysis of the coupling mechanisms between TM alignment errors and TTL coupling noise. We first establish a comprehensive TTL noise model that accounts for alignment errors, then verify and analyze it through optical simulations. This research ultimately clarifies the coupling mechanisms of TM alignment errors in the context of space-borne gravitational wave missions and determines the allowable alignment tolerance specifications required to meet the gravitational wave detection sensitivity requirements. This work provides critical theoretical foundations and design guidance for the ground alignment procedures and on-orbit performance prediction of future space-based gravitational wave detection missions.

Ultraviolet (UV)‐induced degradation (UVID) poses a significant challenge for the prospective mass production of silicon heterojunction (SHJ) solar cells, known for their high efficiency. In this study, the magnified impact of UV radiation when employing a silicon carbide (SiC)‐based transparent passivating contact (TPC) on the front side of SHJ solar cells is reported. A reduction in open‐circuit voltage (VOC), short‐circuit current (JSC), and fill factor of 12%, 6%, and 11%, respectively, is observed after UV exposure. Conventional UVID mitigation measures, UV‐blocking encapsulation, are assessed through single‐cell TPC laminates, revealing an unavoidable tradeoff between current loss and UVID. Alternatively, the utilization of ultraviolet‐downshifting (UV‐DS) encapsulants is proposed to convert UV radiation into the visible light spectrum. An optical simulation method, conducted via OPAL2, is presented to evaluate UV‐DS encapsulants for diminishing UVID in SHJ solar cells with different front contacts. A simple methodology is proposed to mimic the optical property of UV‐DS encapsulants. In the simulation results, additional current gains of up to 0.33 mA cm−2 achievable with suitable UV‐DS encapsulants are highlighted. The factors related to the UV‐DS effects are evaluated and the optimization pathway for UV‐DS encapsulants is elucidated. Ultraviolet‐induced degradation (UVID) challenges the stability of solar cells using heterojunction technology. Magnified UVID in devices utilizing nanocrystalline layers is observed. Ultraviolet‐downshifting (UV‐DS) encapsulation shows a promising prospect. A simplified model is adopted to generate UV‐DS spectra, which is then fed into the OPAL2 simulator. The effects of UV‐DS encapsulation are evaluated, and an optimization pathway is proposed.

In this work we employ the transfer matrix method for the analysis of optical materials properties to simulate and optimize monolithic tandem solar cell devices based on CuIn 1− x Ga x Se 2 , CI(G)S, and perovskite (PVK) absorbers. By finding models that fit well the experimental data of the CI(G)S solar cell, the semitransparent perovskite solar cell (PSC) and the PVK/CI(G)S monolithic tandem solar cell, we were able to perform a detailed optical loss analysis that allowed us to determine sources of parasitic absorption. We found better substitute materials for the transport layers to increase the power conversion efficiency and, in case of semitransparent PSCs, sub-bandgap transmittance. Our results set guidelines for the monolithic PVK/CI(G)S tandem solar cells development, predicting an achievable efficiency of 30%.

Cs2AgBiBr6 (CABB) perovskite is popular for its non-toxic nature and potential for optoelectronic applications, making it a strong candidate in the quest for environmentally friendly perovskite materials. Although it has decent charge-carrier mobility for solar cell applications, the large bandgap of CABB (~2.1 eV) results in the loss of some portion of visible light, resulting in low efficiency. Thus, using a hole transport layer (HTL) with a lower bandgap, which can also act as another suitable absorber layer to capture the transmitted light, can enhance the device’s efficiency. By doing this, we can also replace organic HTL like spiro-OMeTAD, which has limitations, such as cost and early degradation. Here, we demonstrate the potential of MASnI3 (CH3NH3SnI3) perovskite as an HTL in the device ITO/SnO2/CABB/MASnI3/Au due to its p-type character via an optical simulation study. It has a direct bandgap of ~1.3 eV, so it is well-suited to absorb the partially transmitted visible light from CABB and eventually enhance the device’s efficiency. The optical simulation study reveals that replacing spiro-OMeTAD HTL with MASnI3 can significantly enhance the short-circuit current density (Jsc) of the device from 7.81 mAcm−2 to 22.79 mAcm−2. This finding demonstrates the potential of p-type MASnI3 as a hole transport layer to improve the performance of CABB solar cells.

This paper details the development of a polymer-based miniaturized spectrometer as part of the \"Minispectral\" project at Jade University of Applied Sciences. The spectrometer's design leverages advanced injection molding techniques to create a polymer dome, which forms the core structure of the device. A concave diffraction grating is incorporated on the dome's surface to disperse incoming light into its constituent wavelengths. The dome and grating are designed with a generalized Rowland circle radius ratio in three-dimensional space, producing a lens effect for focused detection and analysis. Zemax ray tracing simulations are used to model the optical setup, while wave optics simulations, utilizing Rigorous Coupled-Wave Analysis (RCWA) implemented through Dynamic Link Libraries (DLLs) in Zemax, simulate critical parameters such as dome alignment, blazing, and the line density of the concave diffractive optical element (DOE). These simulations are vital for optimizing the spectrometer's performance. This paper presents the basic design, simulations, and the first test grating masters.

As a commonly used solution, the multi-ended readout can measure the depth-of-interaction (DOI) for positron emission tomography (PET) detectors. In the present study, the effects of the multi-ended readout design were investigated using the leading-edge discriminator (LED) triggers on the timing performance of time-of-flight (TOF) PET detectors. At the very first, the photon transmission model of the four detectors, namely, single-ended readout, dual-ended readout, side dual-ended readout, and triple-ended readout, was established in Tracepro. The optical simulation revealed that the light output of the multi-ended readout was higher. Meanwhile, the readout circuit could be triggered earlier. Especially, in the triple-ended readout, the light output at 0.5 ns was observed to be nearly twice that of the single-ended readout after the first scintillating photon was generated. Subsequently, a reference detector was applied to test the multi-ended readout detectors that were constructed from a 6 × 6 × 25 mm3 LYSO crystal. Each module is composed of a crystal coupled with multiple SiPMs. Accordingly, its timing performance was improved by approximately 10% after the compensation of fourth-order polynomial fitting. Finally, the compensated full-width-at-half-maximum (FWHM) coincidence timing resolutions (CTR) of the dual-ended readout, side dual-ended readout, and triple-ended readout were 216.9 ps, 231.0 ps, and 203.6 ps, respectively.

The exploitation of bifacial solar cells in photovoltaics aims to provide cost-effective solutions to maximize solar power collection on specific surfaces. A prerequisite for this is the effective collection of backscattered diffuse light from albedo, to which self-shading is an obstacle. We discuss the benefits of bifaciality for an asymmetric low-concentrating and spectral-splitting photovoltaic optics system that features a wedged right-prism geometry to address self-shading. The performance of the conceptual design is analyzed, using commercial ray-tracing software, for four different latitudes of installation, by assuming a standard solar AM1.5G spectrum as input. The daily Relative Optical Power Increase (ROPI) is evaluated with respect to standard flat bifacial configurations, reaching ROPI = 293% at a latitude of 25° north at winter solstice. The photocurrent and total Power Conversion Efficiency (PCE) in a four-terminal (4T) configuration are estimated, assuming the operation of a commercial Si HJT bifacial cell and a commercial single-junction GaAs cell. A global increase in PCE of up to 23% is obtained with respect to the best-performing trackless standard bifacial configuration. From this perspective, the use of high-performance, high-bandgap solar cells in 4T configurations might further leverage the advantages of the optics proposed here.

The Mie-scattering lidar can detect atmospheric turbulence intensity by using the return signals of Gaussian beams at different heights. The power spectrum method and Zernike polynomial method are used to simulate the non-Kolmogorov turbulent phase plate, respectively, and the power spectrum method with faster running speed is selected for the subsequent simulation. In order to verify the possibility of detecting atmospheric turbulence by the Mie-scattering lidar, some numerical simulations are carried out. The power spectrum method is used to simulate the propagation of the Gaussian beam from the Mie-scattering lidar in a vertical path. The propagation characteristics of the Gaussian beam using a non-Kolmogorov turbulence model are obtained by analyzing the intensity distribution and spot drift effect. The simulation results show that the scintillation index of simulation is consistent with the theoretical value trend, and the accuracy is very high, indicating that the method of atmospheric turbulence detection using Mie-scattering lidar is effective. The simulation plays a guiding role for the subsequent experimental platform construction and equipment design.