Indoor Applications Research Articles

Spray-Coated Transition Metal Dichalcogenides as Hole Transport Layers in Inverted NFA-Based Organic Photovoltaics with Enhanced Stability under Solar and Artificial Light

In this study, we explored the potential of exfoliated transition metal dichalcogenides (TMDs) as innovative spray-coated hole transport layers (HTLs) in organic photovoltaics (OPVs), addressing the need for efficient and stable materials in solar cell technology. This research was motivated by the need for alternative HTLs that can offer enhanced performance under varying lighting conditions, particularly in indoor environments. Employing UV-visible absorption and Raman spectroscopy, we characterized the optical properties of MoS2, MoSe2, WS2, and WSe2, confirming their distinct excitonic transitions and direct bandgap features. The nanocrystalline nature of these TMDs, revealed through XRD patterns and crystallite size estimation using the Scherrer method, significantly contributes to their enhanced physical properties and operational efficiency as HTLs in OPVs. These TMDs were then integrated into OPV devices and evaluated under standard solar and indoor lighting conditions, to assess their effectiveness as HTLs. The results demonstrated that MoS2, in particular, displayed remarkable performance, rivalling traditional HTL materials like MoO3. It maintained high power conversion efficiency across a spectrum of light intensities, illustrating its versatility for both outdoor and indoor applications. Additionally, MoS2 showed superior stability over extended periods, suggesting its potential for long-term usage in OPVs. This study contributes significantly to the field of photovoltaic materials, presenting TMDs, especially MoS2, as promising candidates for efficient and stable OPVs in diverse lighting conditions, thereby broadening the scope of solar cell applications.

Determination of light-independent shunt resistance in CIGS photovoltaic cells using a collection function-based model

Shunt resistance Rsh is a critical parameter for photovoltaic cells designed for low light indoor applications because it negatively affects the open circuit voltage, fill factor, and conversion efficiency. Standard CIGS cells are known to have low Rsh and are, therefore, unpromising candidates for indoor energy sources. In this paper, we extend the original work of Virtuani et al. by determining the electrical specifications of many CIGS cells with copper contents [Cu]/([Ga]+[In]) as low as 0.33 and gallium contents between 0.28 and 0.81. First, IV data are fitted by a standard single-diode electrical circuit model for each illumination, resulting in light-dependent parameters. Then, we use a procedure based on a single dataset of electrical variables, i.e., independent of light, corrected by the experimental collection function, which captures light-dependent physical mechanisms. In this way, we are able to correctly reproduce the illuminance dependence of the electrical response of the PV cell over three orders of magnitude, in particular with a fixed value of the shunt resistance. The highest Rsh is obtained with a low copper composition of 0.5, regardless of the gallium composition.

UV‐cured epoxy‐acrylate interpenetrating polymer networks with different contents of epoxidized soybean oil

AbstractThis work aims to study the effect of epoxidized soybean oil (ESO) concentration on the process of formation and characteristics of UV‐cured ternary epoxy‐acrylate interpenetrating polymer networks (IPNs). Whereas the amount of triethylene glycol dimethacrylate (TEGDMA) keeps constant, the one of ESO incorporated to substitute the respective quantity of diglycidyl ether of bisphenol A (DGEBA) is equal to 10, 20, and 30 parts by weight (pbw). A total of 30 pbw of ESO is found to be the most effective content for altering the conversion degree of epoxy groups and for enhancing the impact resistance of cured materials while providing their transparency. The addition of ESO induces the decrease in cross‐linking density and in the values of glass transition temperature. The samples exhibite good water and chemical resistance with some variations dependent on their composition. Thermooxidative stability of the specimens gradually reduces as the content of aromatic epoxy decreases. Overall, the introduction of ESO into epoxy‐acrylate IPNs not only lessens the fraction of synthetic epoxide but also facilitates the photopolymerization process of DGEBA and diminishes its brittleness. Considering fine atmospheric resistance testified by accelerated weathering test, given materials may be purposed as transparent films or protective coatings for both indoor and outdoor applications.

Quadrotor with wheels: design and experimental evaluation

Quadrotors have found widespread use in indoor applications, including tracking and mapping. In general, to carry out such tasks effectively, a navigation solution should provide both accuracy and battery efficiency. To achieve both, we propose a cost-effective and lightweight wheeled quadrotor that combines both driving and flying capabilities. Our design allows the quadrotor to perform both functions seamlessly. We provide a detailed description of the design and construction process, highlighting its advantages. Our focus was on the Tello quadrotor, which weighs 80 grams. Our design allowed driving capability with an increased weight of only fifteen grams, resulting in less than 20% of the added weight. Furthermore, we evaluate the quadrotor’s pure inertial navigation performance and corresponding battery consumption by employing various flying and driving patterns. Our results show that when only driving the battery consumption was the lowest with 10% and some flying scenarios improve the positioning error by more than 70%.

Multicomponent organic blend systems: A review of quaternary organic photovoltaics

AbstractEmbedding a third and/or fourth component into a binary blend active layer of organic photovoltaics (OPVs) is a promising approach to achieve high‐performance photovoltaic cells and modules. This multicomponent strategy favors absorption broadening via additional components. Quaternary OPV (QOPV) blends have four components in three possible configurations: (i) a donor and three acceptors, (ii) two donors and two acceptors, or (iii) three donors and an acceptor. Although quaternary systems have only been relatively recently studied compared to other systems in OPVs, leveraging the synergistic effects of the four components leads to record power conversion efficiencies, currently approaching 20%. QOPVs provide ample material choices for compatibility and channels for charge transfer mechanisms, possibly leading to optimized morphology and orientation. Reviewing recent progress in advancing QOPVs is essential for understanding their contribution to the OPV field. The review mainly discusses research progress in QOPVs with a keen interest in their various configurations, semitransparency, and outdoor and indoor applications. It describes the not‐well‐understood QOPV's general working mechanism. This review explores high‐performance QOPVs based on the fourth component's contribution as a donor, acceptor, or dye molecule and beyond in photovoltaic applications. Finally, there is a discussion around QOPV's outlook and projected future research directions in this field. This review intends to provide an overview of the quaternary systems approach to OPVs and inform current and future researchers on investigating the full spectrum of OPVs.

Silicon heterojunction solar cells: Excellent candidate for low light illuminations

The current solar cells and modules are marketed according to the behaviour at standard test conditions (STC), however, these devices are more often operated at lower irradiance levels. The dependence on illumination stems mainly from the voltage at the open circuit and at the maximum power point. The latter might also be strongly influenced by serial resistance, but that is more an engineering problem not addressed here. More fundamentally, the voltage is determined by quasi-Fermi levels at the contacts. In the case of unconstrained conductivity between the absorber and electrode, the quasi-Fermi levels are flat, and determined by their splitting in the absorber. Our analysis shows that the modulation doping mechanism working in Si heterojunction solar cell between the doped amorphous Si layer with a higher bandgap and crystalline absorber with a lower bandgap can, for certain parameter settings, lead to strongly depleted contact layer that limits conduction. This is a prerequisite for decoupling the quasi-Fermi level between contact and absorber and offers the possibility for additional voltage increase. Based on this understanding, we simulate a heterojunction solar cell with a varying thickness and doping of amorphous silicon p-type contact. We demonstrate that for a certain combination of thinner or lower-doped contact, higher efficiency at low illumination can be achieved compared to the technological baseline. This is fully in line with the experimental findings. This analysis is crucial not only for using solar cells for indoor applications but also for designing photovoltaic modules optimized for low irradiance, potentially increasing the level of self-sufficiency of buildings.

Unveiling the potential of bifacial photovoltaics in harvesting indoor light energy: A comprehensive review

Bifacial photovoltaics (BPVs) have received tremendous attention as a potential contender for efficient and cost-effective light energy harvesting. Recently, advancements in BPV technologies have broadened their scope, allowing them to harness artificial indoor light energy efficiently from both top and bottom sides. This innovative approach has demonstrated its effectiveness in energy harvesting through a single-cell design. Among various available PV technologies, thin-film perovskite photovoltaics (PPVs) exhibit exceptional promise for indoor applications in low-light environments. They offer high-power conversion efficiency and ease of design, making them a superior choice when compared to other emerging indoor PV technologies such as kesterite and dye-sensitized PVs. To improve the performance of the indoor BPVs, it is necessary to further review several characteristics relating to their materials, architecture, processing, and indoor characterizations. Additionally, a comprehensive understanding of charge-transfer mechanisms, the variability in indoor lighting sources, the development of standardized indoor simulators, assessment of materials toxicity, and considerations of scalability are essential elements that must be addressed to advance this technology. In summary, this review examines recent developments, emerging trends, challenges, and provide suggestions for the further advancement of i-BPVs, also highlighting their potential as reliable and sustainable indoor energy-harvesting solution.

Indoor organic photovoltaic module with 30.6 % efficiency for efficient wireless power transfer

Organic photovoltaic (OPV) cells possess substantial advantages for indoor applications. However, the underdeveloped cathode interlayer hinders the industrialization of indoor OPV cells. Here, we introduce a phenanthroline derivative with weak nucleophilicity, dicarbolong-phenanthroline (DCP), as the cathode interlayer and comprehensively examine its utilization in indoor OPV cells. DCP exhibits thin depletion region width, which is beneficial for the charge extraction at the interface, thereby contributing to improved power conversion efficiency (PCE). Moreover, DCP presents high adaptability for coating process due to its thickness insensitivity. A DCP-based OPV module is fabricated by blade-coating method, reaching a high maximum output voltage of 4.00 V and a remarkable PCE of 30.6 % at 1000 lux. The OPV module can be successfully applied for efficient wireless power transfer. Furthermore, the DCP-based cell demonstrates outstanding device stability with a lifetime of 32000 hours under indoor lighting. These results demonstrate the promising potential of DCP-based OPV cells for indoor applications.

Design and simulation of 2D Ruddlesden–Popper perovskite solar cells under LED illumination: Role of ETL and front contact band alignment

This paper focuses on the design and simulation of 2D Ruddlesden-Popper halide perovskite (RPHP) solar cells, emphasizing their optimization for indoor LED illumination conditions. The design process begins with the validation of physical models within the SCAPS device simulator, accomplished through careful calibration against experimental (MAMP)MAn−1PbnI3n+1 RPHP cell data. Subsequently, different values of <n> (with n = 1, 2, 3, and 4) are explored to study the impact of different band gap energies, aiming to identify the most suitable option for optimal efficiency across diverse LED color temperatures. By addressing both material-specific considerations and device architecture optimization, this study aims to establish a comprehensive framework for designing RPHP solar cells tailored for white LED illumination. Additionally, the simulation reveals that optimizing the electron affinity of the Electron Transport Layer (ETL) significantly impacts device performance, with efficiencies exceeding 25 %. Furthermore, the study discusses emerging trends such as ETL-free structures, which aim to address interface defects and enhance device performance. In addition, we analyze the impact of bulk trap density and thickness of the 2-D perovskite absorber on efficiency limitations. With an absorber thickness set at 800 nm, a marginal decrease in PCE is observed, for the ETL-free solar cell, from around 34 % to 32 % as the trap density ranges from 1011 to 1014 cm−3. In contrast, for the ETL-based structure with the same variations, PCE experiences a substantial decline, dropping from approximately 47 % to 37 %. While the ETL-free structure may exhibit a lower PCE compared to the ETL-based cell, its capacity to endure fluctuations in trap density offers a notable advantage.These efforts underscore the potential of 2D RPHP photovoltaic cells for indoor applications, presenting a pathway towards efficient, stable, and cost-effective photovoltaic technology suited for diverse lighting environments.

SLAM for Indoor Mapping of Wide Area Construction Environments

Abstract. Simultaneous localization and mapping (SLAM), i.e., the reconstruction of the environment represented by a (3D) map and the concurrent pose estimation, has made astonishing progress. Meanwhile, large scale applications aiming at the data collection in complex environments like factory halls or construction sites are becoming feasible. However, in contrast to small scale scenarios with building interiors separated to single rooms, shop floors or construction areas require measures at larger distances in potentially texture less areas under difficult illumination. Pose estimation is further aggravated since no GNSS measures are available as it is usual for such indoor applications. In our work, we realize data collection in a large factory hall by a robot system equipped with four stereo cameras as well as a 3D laser scanner. We apply our state-of-the-art LiDAR and visual SLAM approaches and discuss the respective pros and cons of the different sensor types for trajectory estimation and dense map generation in such an environment. Additionally, dense and accurate depth maps are generated by 3D Gaussian splatting, which we plan to use in the context of our project aiming on the automatic construction and site monitoring.

Comparative Analysis of the Stability and Performance of Double-, Triple-, and Quadruple-Cation Perovskite Solar Cells for Rooftop and Indoor Applications.

The solar energy market is predicted to be shared between Si solar cells and third-generation photovoltaics in the future. Perovskite solar cells (PSCs) show the greatest potential to capture a share there as a single junction or in tandem with silicon. Researchers worldwide are looking to optimize the composition of the perovskite film to achieve an optimal bandgap, performance, and stability. Traditional perovskites have a mixture of formamidinium and methyl ammonium as the A-site cation in their ABX3 structure. However, in recent times, the use of cesium and rubidium has become popular for making highly efficient PSCs. A thorough analysis of the performance and stability of double-, triple-, and quadruple-cation PSCs under different environmental conditions was performed in this study. The performance of the device and the films was analyzed by electrical measurements (J-V, dark J-V, EQE), scanning electron microscopy, atomic force microscopy, photoluminescence, and X-ray diffraction. The quadruple-cation device with the formula Cs0.07Rb0.03FA0.77MA0.13PbI2.8Br0.2 showed the highest power conversion efficiency (PCE) of 21.7%. However, this device had the least stability under all conditions. The triple-cation device with the formula Cs0.1FA0.6MA0.3PbI2.8Br0.2, with a slightly lower PCE (21.2%), was considerably more stable, resulting in about 30% more energy harvested than that using the other two devices during their life cycle.

Fibre Blend and Web Arrangement for Optimized Dust-Holding, Hydrophobic, and Thermal Properties of Needle-Punched Nonwovens

PM2.5 filters with hydrophobicity and thermal resistance are preferable for automobile cabins, engine air intake, and indoor applications, safeguarding against moisture ingress, microbial growth, and temperature fluctuations, and ensuring optimal air quality. This study explored the effects of blending five fibres with different web arrangements and fibre blend compositions on needle-punched dust-holding, hydrophobic, and thermal properties. Polyphenylene sulfide (PPS), polypropylene (PP), polyester (PET), polylactic acid (PLA), and polyacrylonitrile (PAN) were blended in different proportions to produce the samples. The method included opening, blending, carding, web laying, and needle punching to produce eight samples with cross-laid, parallel-laid, and pre-needled parallel-laid web configurations. Standard test methods were employed for the characterization. The results showed a dust holding capacity of &gt; 3,423,000 particles/cm2, the highest WCA of 133.12°, and the highest thermal resistance of 0.24255 m2KW−1. Based on the ANOVA analysis, web arrangement and pre-needling did not have a significant impact on the hydrophobicity of the samples. N0, N1, and N2 showed similar high water contact angles (~ 126°), indicating that the hydrophobicity was more affected by the chemistry of the fibre blend than by the web structure. Turkey’s analysis of other samples strengthened this idea. However, they had a substantial impact on the porosity, air permeability, dust-holding capacity, and thermal properties at a P-value ≤ 0.05. The findings provide insightful information regarding the complex interactions among fibre content, web layout, and pre-needling to develop sophisticated needle-punched PM2.5 filters.

Quasi-Solid-State Dye-Sensitized Solar Cells by Mechanically Stable Semi-Interpenetrating Network Polymer Gel Electrolytes for Indoor Applications

Quasi-Solid-State Dye-Sensitized Solar Cells by Mechanically Stable Semi-Interpenetrating Network Polymer Gel Electrolytes for Indoor Applications

Side Connection for High‐Efficiency Organic Photovoltaic Modules for Indoor Applications: Shunt Reduction and Performance Improvement

Indoor photovoltaics has attracted increasing attention because of its potential to power devices of the Internet of Things. The power conversion efficiency (PCE) of organic photovoltaic (OPV) cells has reached values beyond 30% under indoor light, but for OPV modules it is still significantly lower. One reason is the full width interconnection of subcells in such modules. Here, a new side connection method is presented which significantly reduces shunts and thus improves performance of OPV modules for indoor applications where a large parallel resistance is crucial. To prove its advantage, OPV modules are fabricated on both indium tin oxide (ITO) and ITO‐free substrates. Under 500 lux cool white light emitting diode light, the highest PCE of ITO‐free side connection modules (SCMs) is 15.1%, while for conventional full width connection modules (FWCMs) it is 14.4%. For ITO‐based modules under 1000 lux, it is 2.3% for FWCMs compared to 12.1% for SCMs. Thermography images show that the improvement stems indeed from the reduction of shunts. Finally, results from experiments as well as from numerical simulations illustrate clearly that efficiency losses stemming from the increased series resistance for the side connection are rather small and that they are overcompensated by the increased shunt resistance.

Optimizing Transport Carrier Free All-Polymer Solar Cells for Indoor Applications: TCAD Simulation under White LED Illumination.

This work inspects the utilization of all-polymer solar cells (APSCs) in indoor applications under LED illumination, with a focus on boosting efficiency through simulation-based design. The study employs a SCAPS TCAD device simulator to investigate the performance of APSCs under white LED illumination at 1000 lux, with a power density of 0.305 mW/cm2. Initially, the simulator is validated against experimental results obtained from a fabricated cell utilizing CD1:PBN-21 as an absorber blend and PEDOT:PSS as a hole transportation layer (HTL), where the initial measured efficiency is 16.75%. The simulation study includes an examination of both inverted and conventional cell structures. In the conventional structure, where no electron transportation layer (ETL) is present, various materials are evaluated for their suitability as the HTL. NiO emerges as the most promising HTL material, demonstrating the potential to achieve an efficiency exceeding 27%. Conversely, in the inverted configuration without an HTL, the study explores different ETL materials to engineer the band alignment at the interface. Among the materials investigated, ZnS emerges as the optimal choice, recording an efficiency of approximately 33%. In order to reveal the efficiency limitations of these devices, the interface and bulk defects are concurrently investigated. The findings of this study underscore the significance of careful material selection and structural design in optimizing the performance of APSCs for indoor applications.

Formation of secondary aerosol by 222 nm Far-UVC irradiation on SO2

222 nm UV indoor disinfection using KrCl* excimer lamps has been gaining popularity due to claims of minimal ocular and skin damage from direct irradiation. However, the secondary aerosol formation under irradiation of KrCl* excimer lamps, which could be an inhalation hazard, is less explored. SO2, a well-known precursor of outdoor sulfate aerosol, is also ubiquitous in indoor environments in urban cities in northern China where coal is used for domestic heating and cooking. In this work, we studied secondary aerosol formation by 222 nm irradiation on SO2, using a Go: PAM flow reactor, a scanning mobility particle sizer (SMPS), and a time-of-flight aerosol chemical composition monitor (ToF-ACSM). The formation of sulfate nanoparticles was found much more effective at 222 nm than at 254 nm and under fluorescent lamp (FL) irradiation at the same UV doses and RH, likely due to different SO2 oxidation mechanisms. We have also found that NH3 and cooking volatile organic compounds (CVOC), as other indoor-relevant gases, promoted the formation of secondary aerosols by 222 nm radiation on SO2. Overall, 222 nm disinfection can generate secondary pollutants in indoor environments. Caution should be taken during its indoor applications, especially in areas with high SO2 concentrations such as coal-fueled households.

Use of natural dyes to color metakaolin-based geopolymer materials

Over the years several colored ceramic-like materials have been prepared by using many synthetic dyes, which are toxic and polluting. Up to date, no studies have been reported on the combination of natural dyes within the geopolymers (also known as amorphous aluminosilicate polymers). In this scenario, natural dyes such as curcumin, chlorophyll, and a freeze-dried grape marc from the wine agrifood supply chain have been employed to investigate their effectiveness ability to color metakaolin-based geopolymers. The colored geopolymers, cured at 25 or 40 °C for 24 h, are characterized after 56 days of ageing time at room temperature by the ionic conductivity and pH measurements, Fourier-Transform Infrared spectroscopy, compressive strength, and color assessment by the color space analysis before and after soaking the samples in water. Eventually, the control geopolymer samples are also characterized for their potential antimicrobial and cytotoxicity properties. The main findings revealed that employing natural dyes to color geopolymers offers a promising alternative to toxic synthetic dyes. The samples retained their color for brief time when exposed to water thus suggesting indoor application. Moreover, all the samples exhibited good geopolymerization as confirmed by FTIR analysis. Notably, samples cured at 25 °C showed better compressive strengths compared to those cured at 40°C. Finally, the bioimpact of these materials suggests that the synthesis in loco of geopolymers is safe for the operator.

Efficiency of working coveralls and chemical resistant gloves in reducing operator exposure to pesticides

Personal Protective Equipment (PPE) is used to reduce exposure when working with chemicals. For pesticides, exposure scenarios comprise mixing and loading (M&L) and application. The exposure prediction model recommended by European regulatory agencies for operator risk assessments—the Agricultural Operator Exposure Model (AOEM) – is based on 48 operator exposure studies involving over 500 professional operators from 10 European countries in typical working situations to assess exposure under realistic field conditions. We used the AOEM data to assess the efficiency of exposure reduction resulting from wearing chemical-resistant nitrile gloves and non-certified working coveralls during M&L (tank and backpack sprayer), applications using groundboom and airblast spraying, and outdoor and indoor (greenhouse) applications using handheld sprayers. All studies indicated consistent and high exposure reduction > 90% for gloves and non-certified coveralls across all investigated scenarios. Exceptions were almost exclusively observed when an operator incorrectly used the PPE. The mean exposure reduction from all operators, including those that used PPE incorrectly, was 95.0% for gloves and 96.4% for polyester/cotton working coveralls during M&L, and 91.1% for gloves and 94.9% for non-certified coveralls during all application scenarios. This analysis confirms the essential role of PPE and non-certified working coveralls in reducing operator exposure to pesticides. Outliers indicate that operators need to be properly trained and adhere to label instructions to apply pesticides according to good agricultural practices.

Environmental impact and economic aspect investigation of incremental, decremented, and no constant lumen output strategies for LED luminaires in indoor applications

Climate change is a hot topic because of its detrimental effects and is a consequence of CO2 emissions. The waste as another harmful factor is of interest. Besides the abovementioned environmental concerns, an interesting aspect of choosing production for the owners is decreasing the expenses related to procurement, installation, and operation. Regarding reducing ecological effects, LEDs as high-efficacy light sources were introduced to the market. LED usage itself has considerations. Two essentials are minimizing excess consumed energy to compensate for luminous flux depreciation and the optimum number of LED luminaires in a lighting system. The energy usage and the number of LED luminaires are directly related to CO2 emission, and the number of LED luminaires is proportional to the amount of waste to the environment. The excess energy usage for compensation of lumen maintenance depreciation is controlled by the constant lumen outputs (CLOs). CLOs are the solution for maintaining a constant luminous flux for the whole lifetime of the LEDs. This research introduces and discusses strategies for using and not using CLOs to find the best strategy for reducing CO2 emission, waste, owner costs for LEDs in indoor lighting systems.

Nano triumphs bulk in red light emission from Eu3+ doped Y2Zr2O7: Gel combustion versus solid state synthesis

Red phosphors are integral element of a phosphor converted white light emitting diodes (pc-WLEDs) which significantly impacts the color rendering index (CRI) and correlated color temperature (CCT) and thus provides a white light suitable for indoor applications. Red Light emitting Eu doped Y2Zr2O7 (YZOE) has been synthesized by two different synthesis methods viz. gel combustion (GC) and solid-state route (SS) wherein the former yielded nanocrystalline and latter leads to bulk YZOE. By virtue of lower light scattering, better electron-hole overlap integral and lower symmetric surrounding, nano YZOE displayed better photoluminescence properties in terms of emission intensity, photoluminescence quantum yield (PLQY) and excited state lifetime compared to its bulkier counterpart.