Article
Chemistry, Physical
Manjot Kaur, Kulwinder Singh, Ram K. Sharma, Akshay Kumar
Summary: This study investigates the electrical transport and photoconductivity properties of WSe2-FeS2 nanocomposite thin films. The analysis reveals multiple carrier transport mechanisms and the influence of trap states. The effect of light on photocurrent is found to be insignificant at low temperatures but increases significantly at higher temperatures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Condensed Matter
C. Figueroa, M. Villafuerte, B. Straube, J. Ferreyra, C. Navarro, V. Runco Leal, G. Bridoux
Summary: Time-dependent photoconductivity and PC spectra were investigated in oxygen deficient BaSnO3 thin films grown on different substrates. The films were epitaxially grown on MgO and SrTiO3 substrates, with the latter being compressively strained in the plane. The electrical conductivity in dark increased by one order of magnitude for the films on SrTiO3 compared to MgO, leading to a significant increase in PC. PC spectra revealed a direct band gap of E-G = 3.9, while the film on SrTiO3 exhibited more defects due to strain, which could explain the differential transition values obtained for both films.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Engineering, Electrical & Electronic
Lars Thole, Asem Ben Kalefa, Christopher Belke, Sonja Locmelis, Lina Bockhorn, Peter Behrens, Rolf J. Haug
Summary: In this study, researchers discovered a persistent photoconductivity phenomenon in TMTC zirconium trisulfide that can last for several hours under illumination. The phenomenon can be described by a stretched exponential function and the sum of three exponential functions with different relaxation times. Additionally, the three observed processes can be differentiated based on the thickness of the thin layers.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Physics, Applied
Patrick Barfield, Vinh Tran, Vikram Nagarajan, Maya Martinez, Amirari Diego, Derek Bergner, Alessandra Lanzara, James G. Analytis, Claudia Ojeda-Aristizabal
Summary: In this work, nanoflake of alpha-RuCl3 was studied through high impedance measurements. The results showed a significant change in transport mechanism at low temperatures and the observation of excitations predicted by the Kitaev-Heisenberg model. This work demonstrated the possibility of realizing the predicted excitations in alpha-RuCl3 at low temperatures and provided information about the transport mechanisms in this material in a wide temperature range.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Fan-Ying Chuang, Denny Pratama Hasibuan, Clara Sinta Saragih, Ranjit A. Patil, Chih-Hung Tsai, Yung Liou, Yuan-Ron Ma
Summary: This study demonstrates how the electron hopping transport in NiO thin films and nanorods is influenced by the length and dimensionality of electron transmission-paths as well as temperature. The electron conduction mechanisms include nearest-neighbor hopping and variable range hopping.
SURFACES AND INTERFACES
(2022)
Article
Physics, Applied
Manjot Kaur, Kulwinder Singh, Akshay Kumar
Summary: The study analyzed the temperature-dependent electrical transport and photoconductivity of WSe 2 / MoS 2 nanocomposite thin films. The results show that chalcogenide vacancies play a crucial role in forming localized states, with the electrical conductivity conforming to Mott's variable range hopping model and higher temperatures showing nearest-neighbor hopping and thermally activated conduction mechanisms.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Hamdi Sukur Kilic, Yasemin Gundogdu, Sumeyye Kilic, Serap Yigit Gezgin
Summary: In this study, Cu2ZnSnS4 nanocrystal and its constituents' copper, zinc and tin were grown separately as thin films using pulsed laser deposition technique. Their linear optical properties were analyzed with UV-Vis absorption spectra, while their nonlinear optical properties were investigated using femtosecond laser pulses. The nonlinear refractive indexes and absorption coefficients of the films were calculated to be around 10(-13) cm(2)/W and 10(-12) cm/W, respectively, with third-order susceptibilities of 10(-11) esu.
OPTICAL AND QUANTUM ELECTRONICS
(2021)
Article
Nanoscience & Nanotechnology
Woo-Jin Lee, Sang-Seok Lee, Sang-Hyun Sohn, Yuna Choi, Il-Kyu Park
Summary: This study reports the effective control of persistent photoconductivity in Zn-doped SnO2 thin films and the enhancement of the performance of solar-blind UV photodetectors. Zn doping plays a critical role in reducing dark current and persistent photoconductivity, thereby increasing photosensitivity and shortening response times.
Article
Physics, Applied
Rohit Saraf, Cecile Saguy, Vivek Maheshwari, Hemaprabha Elangovan, Yachin Ivry
Summary: This study demonstrates that intrinsic polarization conductivity governs photoconductivity in hybrid halide perovskite films, with directional photocurrent flow along the long crystallographic axis and suppression at the tetragonal-to-cubic transformation. Nonvolatile memory behavior of polarization domains leads to photoconductive memristive behavior. Understanding the origin of photoelectric activity in HHPs allows for designing devices with enhanced functionality.
APPLIED PHYSICS LETTERS
(2021)
Article
Energy & Fuels
N. Akcay, V Gremenok, V. A. Ivanov, E. Zaretskaya, S. Ozcelik
Summary: The effect of a thin Al2O3 barrier layer on the performance of CZTS films was investigated. The crystalline qualities of the films did not change significantly with the addition of the Al2O3 layer. Raman spectra and XPS analysis revealed the formation of secondary phases and compounds on the film surfaces. The presence of the Al2O3 layer resulted in changes in surface morphology and Na diffusion rate.
Article
Materials Science, Multidisciplinary
Giorgio Colombi, Bart Boshuizen, Diana Chaykina, Leyi Hsu, Herman Schreuders, Tom J. Savenije, Bernard Dam
Summary: Rare-earth oxyhydride thin films exhibit reversible photochromism and photoconductivity at ambient conditions, but the underlying mechanism and relationship are not clear. In this study, in situ time-resolved measurements of optical and transport properties were performed on Gd-based oxyhydride thin films to investigate this question. It was found that the initial mechanism of charge transport is p-type large polaron conduction; however, upon photo-darkening, a 10(4)-fold increase in conductivity occurs, and n-type carriers dominate. Furthermore, both photochromism and photoconductivity were shown to originate from a single process, as the photoconductivity is exponentially proportional to the increase in optical absorption. This exponential relationship suggests that the formation of optically absorbing species responsible for photochromism is accompanied by a concerted increase in negative charge carriers in the Gd oxyhydride films.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Multidisciplinary Sciences
Ahmad A. Ahmad, A. B. Migdadi, Ahmad M. Alsaad, I. A. Qattan, Qais M. Al-Bataineh, Ahmad Telfah
Summary: This study synthesized and characterized Cu2ZnSnS4 (CZTS) thin films using the sol-gel method and analyzed the effects of different annealing temperatures on the structural and optical properties. The results indicate that annealed CZTS thin films show stable structure and enhanced optical parameters, making them potential candidates for high-efficiency solar cell applications.
Letter
Chemistry, Physical
Guodong Zhang, Yanzhen Li, Yun Liu, Leisheng Su, Yingmin Luo, Yiming Yang, Jijun Qiu
Summary: The vapor phase deposition (VPD) method is demonstrated to successfully deposit uniform PbSe thin films, enabling the industrialization of uncooled lead-salt midinfrared (MIR) detectors. The MIR response of the thin film detector is triggered by the self-assembled rodlike microstructures, controlled by the I2/PbSe flux ratio in the VPD process. This method provides promising optoelectronic performance for MIR detectors.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Physics, Condensed Matter
Y. Jayasree, Y. B. Kishore Kumar, G. Suresh Babu, P. Uday Bhaskar
Summary: In this study, CZTS thin films were successfully prepared using a hybrid chemical method, with a process involving sequential growth of SnS and ZnS layers followed by conversion to CuxS and then CZTS. XRD analysis and Raman spectra confirmed the formation of CZTS phase with a band gap of 1.42 eV and p-type nature of the films.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Chemistry, Physical
Ana Luiza Costa Silva, Ariano De Giovanni Rodrigues, Renato Goulart Jasinevicius, Marcio Peron Franco de Godoy
Summary: In this study, we systematically investigated the room temperature photoconductivity of polycrystalline Co3O4 thin films grown by spray pyrolysis. By using different excitation wavelengths, we were able to access the optical absorption edges related to Co2+ or Co3+. The density of oxygen vacancies in the films could be modified by annealing, and the reduction of Co3+ to Co2+ on the film surfaces was observed.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
P. Kannappan, B. P. Falcao, K. Asokan, J. P. Leitao, R. Dhanasekaran
Summary: Native defects and unintentional contaminations can impact the optical properties of semiconductors. This study explores the effect of defects on a ZnSe crystal grown by chemical vapour transport. The researchers observed four near-band edge transitions and three deeper defect-related transitions. They also proposed a model involving a Zn vacancy for a specific radiative transition.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Juan Carlos Gonzalez, Henrique Limborco, Rodrigo Ribeiro-Andrade, Bruno Cordeiro Silva, Klaus Krambrock
Summary: The study on nanocrystalline selenium poor Sb2Se3 reveals that electrical transport is dominated by a shallow acceptor at low temperature and a deep donor at high temperature. Experimental techniques confirm the existence of a contradictory shallow acceptor and suggest the presence of an unreported shallow defect.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Mariana Bras, Julia Zanoni, Bruno P. Falcao, Joaquim P. Leitao, Florinda M. Costa, Teresa Monteiro, Sonia O. Pereira, Joana Rodrigues
Summary: Antibiotic pollution is a global concern, so it is important to develop cost-effective and reliable devices for detecting these contaminants. In this study, zinc oxide nanostructures were used as transducers in a fluorescent immunosensor to detect tetracycline. The nanostructures had a high surface area and could interact with antibodies and tetracycline molecules, providing a sensing mechanism. The sensor could quantitatively detect tetracycline in the range of 0.001 to 1 μg/L with a low limit of detection, indicating its advanced performance in this field.
ACS APPLIED NANO MATERIALS
(2022)
Article
Energy & Fuels
Andre F. Violas, Antonio J. N. Oliveira, Jennifer P. Teixeira, Tomas S. Lopes, Joao R. S. Barbosa, Paulo A. Fernandes, Pedro M. P. Salome
Summary: Cu(In,Ga)Se2 (CIGS) solar cells are high-performance thin-film technologies that can benefit from post-deposition treatments (PDT) and ultrathin absorbers. However, electrical and optical limitations hinder their widespread implementation. In this study, an updated and experimentally based baseline model for electrical simulations in SCAPS software is developed, incorporating PDT effects and improved optical accuracy. The model is validated with champion solar cells and applied to ultrathin CIGS devices, paving the way for an ultrathin baseline model. Simulation results show that addressing inherent limitations can achieve ultrathin solar cells with high power conversion efficiency.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Energy & Fuels
Kevin Oliveira, Jennifer P. Teixeira, Wei-Chao Chen, Jackson Lontchi Jioleo, Antonio J. N. Oliveira, Ihsan Caha, Leonard Deepak Francis, Denis Flandre, Marika Edoff, Paulo A. Fernandes, Pedro M. P. Salome
Summary: In this study, SiO$_x$ passivation based substrates were developed and integrated into ultrathin Cu(In,Ga)Se$_2$ (CIGS) solar cells to investigate the impact of SiO$_x$ layer thickness on the device performance. Experimental study and optical/electrical simulations were conducted to decouple the optical and electronic gains of the SiO$_x$ layer, allowing for a detailed analysis of its effect on the CIGS solar cell performance. The results showed that an increase in passivation layer thickness led to a rise in parasitic losses, indicating the importance of finding a balance between beneficial passivation and optical effects with harmful architectural constraints to achieve optimal solar cell performance.
IEEE JOURNAL OF PHOTOVOLTAICS
(2022)
Article
Chemistry, Analytical
Geovani Torezin Mendonca, Mateus Cassaboni Stracke, Bruna de Oliveira Coelho, Heloisa Bruna Soligo Sanchuki, Viviane Klassen de Oliveira, Fabricio Klerynton Marchini, Dalila Luciola Zanette, Mateus Nobrega Aoki, Emilson Ribeiro Viana, Lucas Blanes
Summary: This work presents the development of a portable Lab-on-a-Chip (LOC) instrument for Point-of-Care (POC) diagnosis of SARS-CoV-2 using Reverse-Transcription Loop-mediated isothermal amplification (RT-LAMP). The instrument utilizes a Raspberry Pi computer, a video camera, an Arduino Nano microcontroller, a printed circuit board as a heater, and a 3D printed housing. The chips are made of polymethyl methacrylate (PMMA) and are sealed with a PCR optic plastic film. The chip temperature is precisely controlled using a PID algorithm. The diagnostic process involves color image recognition and achieves an accuracy of 86% when compared to the results obtained by conventional PCR equipment.
MICROCHEMICAL JOURNAL
(2022)
Article
Nanoscience & Nanotechnology
E. R. Viana, N. Cifuentes, J. C. Gonzalez
Summary: The electronic transport properties of Te roll-like nanostructures were investigated in a broad temperature range. The nanostructures exhibited p-type conductivity with enhanced hole mobility at low temperatures, and nearest-neighbor hopping conduction dominated at high temperatures. These results demonstrate the potential applications of these nanostructures in nanodevices.
BEILSTEIN JOURNAL OF NANOTECHNOLOGY
(2022)
Article
Energy & Fuels
Daniel Rocha, Joao Alves, Vitor Lopes, Jennifer P. Teixeira, Paulo A. Fernandes, Mauro Costa, Modesto Morais, Pedro M. P. Salome
Summary: Unmanned aerial vehicles (UAVs) with high-resolution optical and infrared (IR) imaging have been used for fast and cost-effective inspections in solar power plants. However, the analysis of the acquired images is still time-consuming and requires trained professionals. This study compares the performance of mask R-CNN and U-Net for image analysis in a 10-MW solar power plant, achieving high precision and outperforming U-Net in terms of IoU.
IEEE JOURNAL OF PHOTOVOLTAICS
(2023)
Article
Environmental Sciences
Rodrigo de Lazzari, Edgar H. Souza, Susan Y. Zanetti, Emilson R. Viana, Anna L. M. C. Malthez
Summary: In this study, the sensitivity of a newly designed OSL system was compared with two commercial systems by performing OSL readouts of Al2O3:C irradiated with different doses. The newly designed system used a cluster of blue LEDs for optical stimulation in both continuous wave (CW-OSL) and pulsed (POSL) modes, and a bandpass filter was used for detection. The results showed that the developed reader could be used for OSL readouts of detectors exposed to both low doses in POSL mode and high doses in CW-OSL mode.
RADIATION PROTECTION DOSIMETRY
(2023)
Article
Engineering, Electrical & Electronic
T. S. Lopes, J. P. Teixeira, M. A. Curado, B. R. Ferreira, A. J. N. Oliveira, J. M. V. Cunha, M. Monteiro, A. Violas, J. R. S. Barbosa, P. C. Sousa, I. caha, J. Borme, K. Oliveira, J. Ring, W. C. Chen, Y. Zhou, K. Takei, E. Niemi, F. L. Deepak, M. Edoff, G. Brammertz, P. A. Fernandes, B. Vermang, P. M. P. Salome
Summary: The study demonstrates the incorporation of interface passivation structures in ultrathin Cu(In,Ga)Se-2 based solar cells. A scalable lithography technique, nanoimprint lithography (NIL), was used to pattern a 15 x 15 cm(2) dielectric layer. The performance of devices with NIL nanopatterned dielectric layer was similar to that of devices with electron-beam lithography (EBL) patterning. The impact of lithographic processes on solar cell performance was evaluated, with stainless-steel substrates showing slightly lower performance but good mechanical stability.
NPJ FLEXIBLE ELECTRONICS
(2023)
Article
Engineering, Mechanical
Joelton Deonei Gotz, Gabriel Carrico Guerrero, Jose Renan Holanda de Queiroz, Emilson Ribeiro Viana, Milton Borsato
Summary: The rapid growth of the electric car industry in recent years is driven by the use of stable lithium-ion batteries (LIBs). Although LIBs are widely used in energy storage systems for electric mobility, laptops, and cell phones, they are still prone to failures that can pose security and performance issues. To identify failures at an early stage, this study applies six classification machine learning models to LIBs, achieving a sensitivity rate of over 94% for mechanical, electrical, and thermal failures. The random forest model performs the best with a sensitivity rate over 97%. This approach can effectively detect failures in LIBs and has the potential to be integrated into vehicles for online abuse classification, reducing security and performance risks.
ENGINEERING FAILURE ANALYSIS
(2023)
Article
Green & Sustainable Science & Technology
Joelton Deonei Gotz, Joao Eustaquio Machado Neto, Jose Rodolfo Galvao, Taysa Millena Banik Marques, Hugo Valadares Siqueira, Emilson Ribeiro Viana, Manoel H. N. Marinho, Mohamed A. Mohamed, Adrian Ilinca, Fernanda Cristina Correa, Milton Borsato
Summary: The increased adoption of electric vehicles has led to a demand for new energy storage systems, with Lithium-ion batteries being the mainstream technology. However, the complex configuration of the batteries complicates the diagnosis of misuse and failure. This study conducted experiments on a mini-packing of four cells to simulate the main abuses found in Lithium-ion batteries. The results showed that current, temperature, and voltage can be used to identify external short-circuit failures, voltage signature can determine Over-Charging, and the combination of temperature and voltage can identify and locate Over-Discharging failures.
Review
Materials Science, Multidisciplinary
Antonio J. N. Oliveira, Jennifer P. Teixeira, Duarte Ramos, Paulo A. Fernandes, Pedro M. P. Salome
Summary: Light management is crucial for the expansion of CIGS technology market, as it can improve conversion efficiency and reduce costs. However, there are fabrication and architecture constraints that hinder the direct transfer of light management strategies from other photovoltaic technologies. This study analyzes the demand for light management in thin and ultrathin CIGS cells and identifies three main pathways to tackle optical losses. The review provides insights into the challenges and developments of light management architectures, presenting a research roadmap for future works in this area.
ADVANCED PHOTONICS RESEARCH
(2022)
Article
Chemistry, Physical
Diogo F. Carvalho, Manuel A. Martins, Paulo A. Fernandes, M. Rosario P. Correia
Summary: Understanding the plasmonic coupling between metallic nanoparticles (NPs) in a 2D array and the effect of a semiconductor substrate is crucial for optimizing optoelectronic structures. This study presents a simple semi-analytical approach based on the discrete dipole approximation (DDA) to simulate the far-field and near-field properties of NP arrays, taking into account particle coupling and the presence of a semiconductor substrate. The method is validated for Ag NP dimers and single Ag NPs on a GaN substrate, and then applied to square and random arrays of Ag NPs. It is found that increasing the NP surface density on a GaN substrate results in a redshift of the dipolar resonance frequency and enhanced near-field properties. The single dipole approach used in this model allows for efficient computational times, making it advantageous for predicting optical properties in large NP arrays on semiconductor substrates for various applications.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
