32 https://uvadoc.uva.es/handle/10324/1158 2026-04-25T16:11:31Z 2026-04-25T16:11:31Z Mateo Romero, Héctor Felipe Hernández Callejo, Luis González Rebollo, Miguel Ángel Martínez Sacristán, Óscar Redondo Plaza, Alberto Gregorio Amami, Ghada Alonso Gómez, Víctor https://uvadoc.uva.es/handle/10324/83965 2026-04-08T19:13:53Z 2026-01-01T00:00:00Z

This work presents a novel database architecture designed to support laboratory-based experimentation with photovoltaic (PV) cells and modules using different kinds of measurements, such as Electroluminescence (EL) Images or Current-Voltage (I-V) curves. The database is implemented in MySQL following established design principles. A web-based application is presented for efficient data insertion and retrieval. The initial population includes over 800 EL images and I–V curves of PV cells, and more than 1100 records of PV modules from diverse installations. This database provides a foundational tool for advancing automated diagnostics, performance analysis, and the integration of Artificial Intelligence in PV research environments. Future work will focus on enhancing the system’s scalability, interoperability, and support for real-time data ingestion and user management.

2026-01-01T00:00:00Z Tran, Thi Ha Pham, Nguyen Hai Tran, Van Tan Martínez Sacristán, Óscar Tsay, Jyh-Shen Nguyen, Viet Tuyen Pham, Van Thanh https://uvadoc.uva.es/handle/10324/82297 2026-03-27T12:05:40Z 2026-01-01T00:00:00Z

In this study, we present a fast and facile self-resistive heating method to fabricate copper oxide (CuO) nanowires (NWs) using copper wire substrates. The effect of growth temperature and time were investigated through both experiment and simulations. X-ray diffraction and Raman spectroscopy confirmed the successful formation of highly crystalline CuO phase. Scanning electron microscopy images demonstrated that the NWs were uniform in size and at high density, indicating an efficient synthesis process. Additional analyses were conducted to further elucidate a thermodynamic mechanism of the growth of CuO NWs. Our extensive experimental and simulation data on synthesis parameters provide a detailed view on the growth of the NWs and explain the efficient growth of aligned CuO NWs synthesized by the resistive heating method.

2026-01-01T00:00:00Z Tran, Van Tan Le, Minh Phuong Pham, Nguyen Hai Nguyen, Viet Tuyen Pham, Thi Hong Sai, Cong Doanh Nguyen, Quang Hoa Pham, Van Thanh Nguyen, Thanh Binh Nguyen, Trong Tam Ngac, An Bang Martínez Sacristán, Óscar Tran, Thi Ha https://uvadoc.uva.es/handle/10324/81870 2026-04-09T07:40:04Z 2024-01-01T00:00:00Z

Surface-enhanced Raman scattering (SERS) is a powerful technique for detecting pollutants. Recent studies have shown that the sensitivity of SERS can be further improved by using appropriate light excitation before or during Raman measurements, a phenomenon known as photo-induced enhanced Raman scattering (PIERS). In this study, we developed a highly sensitive SERS substrate by fabricating a ZnO/Au thin film using radio frequency magnetron sputtering and post-annealing processes. The resulting substrate exhibited high crystallinity and high sensitivity for pollutant detection. The study found that in situ UV excitation significantly enhanced the Raman signal, up to 5.5 times more efficiently than the traditional SERS technique. The excitation process was reversible, leading to a quick recovery of the Raman intensity to its initial level when the UV excitation was turned off. This relaxation process is attributed to the recombination of electrons and holes. The investigation shows that ZnO/Au thin films was able to detect fungicide thiram with a limit of detection of 10 8 M. PIER also helps to lower the detection threshold down to 10 9 M.

2024-01-01T00:00:00Z Sulca Buitrón, Kabir Paul Prado Santamaría, Rodrigo del Kari, Thøger Anaya Calvo, Julián Reis Benatto, Gisele Alves dos Spataru, Sergiu Viorel Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/81868 2026-04-08T10:31:49Z 2025-01-01T00:00:00Z

Daylight electroluminescence (dEL) inspection using InGaAs cameras has proven to be a powerful technique for assessing the condition of photovoltaic (PV) modules in the field. Recent advancements have shown it suitable for quality control and evaluation tasks in large-scale solar installations. The quality of dEL images is crucial for accurately identifying potential defects. Therefore, it is important to determine which camera optical stack yields stronger signals in dEL imaging. Camera optical stacks typically include specialized short-wave infrared (SWIR) lenses and bandpass filters to reduce background sunlight. To further limit the light intensity reaching the sensor and prevent saturation, options include adjusting the lens iris, using neutral density (ND) filters, or reducing exposure time. The choice among these depends on system constraints. Even though reducing exposure time is the easiest way to accomplish no saturation, high exposure time reduces noise, so ND filters and the iris are interesting options independent of the camera’s internal controller. This study compares the light intensity reduction methods between ND filters and iris providing higher EL and dEL image quality using signal-to-noise ratio (SNR) as metric. Two SNR metrics (SNRkari and SNR(25)) are used to evaluate the configurations. We compare two setups: one using a C-RED 3 InGaAs camera with a SWIR lens (F-stop range 1.4–16) and a bandpass filter, and another using the same camera and lens fixed at Fstop 1.4 (fully open) combined with ND filters of varying transmittance (0.73 to 0.02). Indoor EL data is used to characterize light attenuation for each configuration. Subsequently, dEL images are captured under 600-800 W/m² irradiance for both setups. The results show that using the iris to reduce light intensity yields higher image quality. This is attributed to the increased depth of field resulting from a smaller optical aperture, which enhances the focus range and sharpness of the captured images. In conclusion, the study demonstrates that using a lens with an adjustable iris is more effective for dEL imaging with InGaAs cameras. This finding is valuable for optimizing optical setups to achieve high-SNR images in PV module inspections.

2025-01-01T00:00:00Z Terrados López, Cristian de la Viuda, Eva Sulca Buitrón, Kabir Paul Anaya Calvo, Julián González Rebollo, Miguel Ángel Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/81867 2026-04-08T11:58:31Z 2025-01-01T00:00:00Z

Daylight Electroluminescence and Photoluminescence techniques (dEL/dPL) have rapidly advanced in recent years and are now well-established tools for the characterization of photovoltaic (PV) Si solar modules in the field. Performing dEL/dPL requires cameras capable of working in the near IR region of the light spectrum (such as InGaAs cameras) and sophisticated filtering procedures to distinguish the weak luminescence emission coming from the PV module from the more intense ambient light. Effective filtering of the weak luminescence requires specific acquisition schemes, both synchronous and asynchronous methods can be used for this purpose. Asynchronous schemes are more convenient, but they usually rely in expensive programmable power sources that produce high quality square or sinusoidal waveforms for the controlled current injection into the PV modules. When paired with fast InGaAs cameras (600 fps), dEL images can be obtained using very short (sub-second) acquisition times. However, the requirement for these programmable power sources may be a significant barrier to rapid in-field deployment of the technique. In this work we show the results of using asynchronous daylight luminescence inspections obtained without programmable power sources, using external control to modulate a DC signal from any power source, including the neighbor panels, or even without the use of a power source but using the Sun as the light source, in the dPL case. We specifically study the shape of the generated current and voltage signals, comparing the external control case with the case of using a programable power source. We also study the impact of varying the modulation frequency and camera speed on image quality and how these acquisition parameters influence performance. This approach broadens the applicability of the dEL technique, enabling effective filtering and identification of panel defects under self-powered or sunlight-driven conditions.

2025-01-01T00:00:00Z Carpintero Gómez, Luis Alberto Terrados López, Cristian González Francés, Diego Sulca Buitrón, Kabir Paul Alonso, V. González Delgado, Manuel Ángel Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/78657 2026-04-08T12:07:36Z 2025-01-01T00:00:00Z

Electroluminescence (EL) imaging is a widely used tool for identifying defects in the solar cells of photovoltaic (PV) modules. Traditional EL inspections require dark conditions and module disassembly, making them costly and logistically challenging. Daylight Electroluminescence (dEL) has emerged as a cost-effective alternative, enabling on-site inspections under any irradiance conditions without module dismounting and thereby reducing costs. However, EL inspections require current injection, necessitating an external power source. Solutions like bidirectional inverters have been proposed to address this challenge. This study proposes a novel self-powered dEL methodology that uses other PV strings in the plant to supply the necessary current. The method employs a switching procedure to filter ambient light and allows entire string inspection without dismounting modules or using external power. Field tests across various irradiance conditions show that the resulting images are com- parable to those obtained in controlled darkroom environments, validating the method’s effectiveness and operational advantages.

2025-01-01T00:00:00Z Terrados López, Cristian González Francés, Diego Sulca Buitrón, Kabir Paul González Delgado, Manuel Ángel Castro Caballero, Carmelo de Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/78649 2025-12-15T20:02:38Z 2025-01-01T00:00:00Z

Daylight photoluminescence (dPL) has emerged in recent years as a useful tool for inspecting solar panels, allowing for theidentification of various types of defects with good spatial resolution and is now considered a useful technique for on-site quali-fication of field-deployed PV modules. The advantage of dPL is that it does not require an electrical power source, although theswitching between two states is generally necessary to filter the ambient light. Several practical solutions have been implementedto carry out this type of measurement. In this paper, we describe the method based on the fast electrical switching using anelectronic device connected to a string or substring in such a way that allows it to be switched between two states, with differentcurrents drawn from the panels. The inspection is carried out with the string in operation, which makes it easier to monitor thecondition of the panels throughout the life of the installation. The advantage of this method is being able to switch—in a veryfast and noninvasive manner—the state of the string, between the maximum power point state and a state at (or very close to)open circuit conditions, once the electrical device has been installed. A demonstrative test has been carried out on a substring ofpanels, testing the response of two different inverters, in addition to a demonstration (using a microinverter) related to inspectinga whole string. Changes in the currents drawn from the panels, the response of the inverter, the background filtering procedure,and the quality of the images obtained are discussed in detail. dPL measurements obtained using this procedure are comparedwith previous dPL measurements and with daylight electroluminescence (dEL) measurements in order to verify the informationprovided by this new procedure.

2025-01-01T00:00:00Z Barroso Solares, Suset López Moya, Federico Fraile, Teresa Prieto Colorado, Ángel Carmelo López Llorca, Luis Pinto Sanz, Javier https://uvadoc.uva.es/handle/10324/77004 2025-07-30T19:00:55Z 2025-01-01T00:00:00Z

Investigation of cell wall composition is necessary to understand the interactions between fungi and the environment as it is the external layer exposed to stimuli and detected by other organisms. Pochonia chlamydosporia and Akanthomyces lecanii, two fungal species living in the soil and infecting nematodes and insects, exhibit endophytic interactions with various plant species. Determination of cell wall composition is essential to understand the mechanisms underlying these interactions. Therefore, in this study, for the first time, we assessed the relative amounts of chitin and chitosan in the cell walls of P. chlamydosporia (PC123) and A. lecanii (69NZ, 85SCT, 126KNY, and 447SAF) via Raman spectroscopy. The isolate with the highest chitosan percentage was 69NZ, followed by 85SCT, PC123, 447SAF, and 126KNY. Moreover, combination with conventional approaches for chitin and chitosan quantification yielded quantitative results for all cell wall components. Overall, these results highlight the mechanisms by which fungi exhibit chitosan resistance and avoid detection by the host plant during root colonization.

2025-01-01T00:00:00Z Hinojosa Chasiquiza, Vanessa Giselle Mediavilla Martínez, Irene Jiménez López, Juan Ignacio Baron, Thierry Serrano, Jorge https://uvadoc.uva.es/handle/10324/75338 2025-09-19T08:41:01Z 2023-01-01T00:00:00Z

Silicon nanowires (NWs) with axial homojunctions have exhibited superior forward current density compared to traditional bulk silicon p-n junctions, making them highly promising for photovoltaic applications with minimal absorption losses. In particular, understanding the intricate interplay between dopants and these structures is crucial for enhancing the NW properties. Contactless optical techniques are suitable for NW characterization, in particular micro-Raman spectroscopy permits the analysis of axial p-n junctions in Si NWs using the Fano asymmetry parameter (q). The micro-Raman scan along the NW allows us to distinguish the n-type segment, the charge-depleted region at the p-n junction, and the p-type segment. Micro-Raman spectroscopy allows contactless estimation of the free carrier concentration, together with structural characterization, and the junction characteristics.

2023-01-01T00:00:00Z Terrados López, Cristian González Francés, Diego Sulca Buitrón, Kabir Paul de Castro, Carmelo González Rebollo, Miguel Ángel Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/75237 2025-09-24T08:18:55Z 2024-01-01T00:00:00Z

Daylight Photoluminescence (dPL) has appeared in recent years as a useful tool for the inspection of solar panels, allowing for the identification of several kind of defects with good spatial resolution. The commutation between two states (On and Off) is usually necessary for the filtration of the ambient light. Several practical solutions have been implemented to do this kind of commutation, both electrically or optically. Here we explore in detail the method consisting on the electrical commutation using an electronic device connected in parallel to an adequate number of panels of a string, allowing to inspect the panels during operation, which is contactless once the electrical device is installed. The method can be also applied for the inspection of whole strings, in this case the electronic device is connected in series to the string to be inspected. The advantage of the method is the very fast commutation of the state of the string, between the MPP state and a state at/or very close to OC conditions. The values of the On and Off signals, the process and quality of the images, and the response of the inverter have been checked.

2024-01-01T00:00:00Z Carpintero, Luis Alberto Terrados López, Cristian González Francés, Diego Martínez Sacristán, Óscar González, Miguel Ángel Alonso Gómez, Víctor https://uvadoc.uva.es/handle/10324/75218 2025-09-24T08:19:19Z 2023-01-01T00:00:00Z

More efficient and cost effective procedure for large scale daylight EL dEL measurements in PV plants. Pillars of this strategy working during the day without disassembling the modules and without the use of power supplies. An InGaAs camera (model Hamamatsu C 12741 03 640 x 512 pixel) has been used to take the dEL images

2023-01-01T00:00:00Z Terrados López, Cristian González Francés, Diego Alonso Gómez, Víctor González Rebollo, Miguel Ángel Jiménez López, Juan Ignacio Martínez Sacristán, Óscar https://uvadoc.uva.es/handle/10324/75209 2025-09-24T08:18:25Z 2023-01-01T00:00:00Z

Nowadays, silicon solar plants consist of hundreds of thousands of panels. The detection and characterization of solar cell defects, particularly on-site, is crucial to maintaining high productivity at the solar plant. Among the different techniques for the inspection of the solar cell defects, luminescence techniques provide very useful information about the spatial distribution of defects. Electroluminescence performed in dark conditions (nEL) is the most commonly used technique. However, daylight EL (dEL) and daylight photoluminescence (dPL) have recently attracted interest, because they present noteworthy advantages for on-site inspections. In this paper, we present a detailed characterization of both damaged mono- and multicrystalline silicon solar cells using dEL and dPL, comparing the results provided by these techniques with those obtained with high-resolution nEL and indoor PL (performed under excitation with a laser diode). Among these techniques, dEL provides reliable and reproducible results, while dPL shows more dependence on the experimental conditions, demanding additional efforts for analysis. The limited resolution obtained with the actual IR camera technologies is a limiting factor of the dEL and dPL techniques. On the other hand, they can be performed on-site, testing a very large number of panels. Therefore, we can assert that on-site dEL is well suited for massive inspection of solar plants, while more research is necessary for dPL.

2023-01-01T00:00:00Z Barroso Solares, Suset Estalayo, E. Aramendia, J. Rodriguez Gutierrez, E Sanz Mínguez, Carlos Prieto, A. C. Madariaga, J. M. Pinto Sanz, Javier https://uvadoc.uva.es/handle/10324/75201 2025-03-03T20:00:59Z 2024-01-01T00:00:00Z

Pre-Roman glass craftsmanship reached its summit with the development of complex polychrome glass beads, being the Phoenician glass pendants the most exquisite and elaborate example. The uniqueness and complexity of such findings could reveal key information for the understanding of the production and trade of glass pieces at that age. However, these findings have practically never been studied from a physic-chemical perspective. In this work, a remarkable polychrome glass pendant (2nd -1st c. BC) found at the archaeological site of Pintia (Padilla de Duero, Valladolid, Spain) is studied by a multi-analytical non-destructive approach, employing X-ray tomography to understand its fabrication procedure, as well as X-ray fluorescence (XRF) and Raman spectroscopy, both employed in microscopic mode, to determine the composition of each glass employed in its fabrication. The outstanding preservation state and well-defined archaeological context of this glass pendant offered a unique opportunity to expand the understanding of pre-Roman glass pieces, while the combination of the experimental techniques employed provided the first complete and detailed study of a Phoenician glass pendant. The fabrication procedure of the pendant has been identified step-by-step, showing evidence of the use of pre-made pieces for the eyes, as well as hints of its fabrication in a secondary workshop. Moreover, the microchemical analysis of the vividly colored glasses by XRF and Raman spectroscopy revealed a composition compatible with the use of natron as fluxing agent, typical of Phoenician glass, the presence of surface alterations corresponding to carbonatation processes, as well as the nature of the employed chromophores or pigments: Mn, Cu, and Co for the blue, Fe-S for the black, CaSb2O7 and CaSb2O7 + TiO2 for two diverse white glasses, and a pyrochloric triple oxide (Pb2Sb2 − xSnxO7−x/2) and lead oxides for the yellow. Remarkably, the use of pyrochloric triple oxides as yellow pigments has scarcely been previously reported at that age. Finally, the identification by Raman spectroscopy of CaSb2O7 and the β-phase of CaSiO3, as well as the Raman spectra features of the glass matrix corresponding to the blue glass, indicated maximum firing tem- peratures below 1100 °C.

2024-01-01T00:00:00Z Amezúa Arranz, Clara Oliveira Salmazo, Leandra López Gil, Alberto Rodríguez Pérez, Miguel Ángel https://uvadoc.uva.es/handle/10324/75175 2025-02-27T20:01:09Z 2024-01-01T00:00:00Z

The global plastic consumption, as one of the paramount concerns of our society, opens new paths of investigation in green materials. This study presents contribution to the field with the obtention of natural rubber latex foams (NRLF using egg white powder (EW) as the biostabilizing agent. The route followed to develop these samples is based on a two-step process, a previous aeration, followed by microwave dehydration. This synthesis route is greener and ecofriendlier than conventional ones due to the use of bio-based bulk materials, the utilization of microwave radiation which reduces the energy consumption in comparison with conventional heating methods, and the elimination of the vulcanization process typically used when producing latex foams. Herein, a deep study of the effect of EW on NRLF obtained at three water content levels (i.e., 40, 70, 90 phr) is carried out. The density and cellular structure parameters are measured for the formulations of liquid and solid foams to comprehend the stabilization mechanisms due to the presence of the EW and the effect of water content. It has been possible to produce open-cell natural rubber latex foams with densities as low as 53 kg m−3 and cell sizes as low as 114 μm.

2024-01-01T00:00:00Z Hurtado García, Violeta Pinto Sanz, Javier Barroso Solares, Suset https://uvadoc.uva.es/handle/10324/75100 2025-02-24T07:24:52Z 2024-01-01T00:00:00Z

Electrospun polymeric membranes, crucial in industries like water treatment, biomedical engineering, and gas separation, rely on their mechanical properties, including tensile strength, elasticity, and durability, for effectiveness and longevity. Optimal mechanical properties enable those membranes to withstand pressure fluctuations, aggressive chemicals, and various usage cycles, enhancing operational efficiency and sustainability. The tunability of these properties is key to customizing membranes for specific applications. In this regard, Atomic Force Microscopy (AFM) has proven its efficacy in the nanomechanical characterization of soft materials over the past two decades. This work reviews recent literature on AFM methods to measure mechanical properties in electrospun materials, discussing their potentialities and current applications.

2024-01-01T00:00:00Z Torre Ordás, Jorge Barroso Solares, Suset Rodríguez Pérez, Miguel Ángel Pinto Sanz, Javier https://uvadoc.uva.es/handle/10324/75099 2025-02-24T07:22:12Z 2024-01-01T00:00:00Z

Understanding how polymer chains are altered by confinement or physical constraints not only is a fundamental question in polymer physics but also holds significant relevance across various fields, as it can elucidate diverse properties of the macroscopic materials. This phenomenon takes places in a wide variety of nanomaterials with different geometries. In the last decade, fabricating and researching polymeric nanomaterials has raised interest as their properties can overcome those of the starting polymer. It is thought that molecular confinement could help tailor mechanical, thermal, rheological, or chemical properties. Therefore, this review aims to present an overview of the recent advancements in the study of the dynamics of polymeric chains within different polymeric nanomaterials, putting emphasis on nanoporous ones. The review includes (i) a description of diverse polymeric nanomaterials and the origin of molecular confinement and its influence on their properties, (ii) an overview of the advancements on molecular confinement and its effects on polymeric nanoporous materials, and (iii) a summary of well-stablished facts and knowledge gaps.

2024-01-01T00:00:00Z