Visible and near-infrared organic photosensitizers comprising isoindigo derivatives as chromophores: synthesis, optoelectronic properties and factors limiting their efficiency in dye solar cells

The development of ruthenium-free organic photosensitizers showing panchromatic absorption up to the near-infrared (NIR) region for application in dye-sensitized solar cells (DSSCs) is still scarce. Among the sensitizers with absorption beyond 700 nm and developed for DSSCs, only zinc-phthalocyanine and boron-dibenzopyrromethene-based dyes have been able to reach efficiencies as high as 6%. Here we report metal-free organic dyes based on isoindigo, thieno-isoindigo or benzo-thieno-isoindigo chromophores that absorb in the UV-visible and NIR spectral range up to 900 nm. These molecules, that exhibit purple, blue, or green hues, were used to sensitize TiO2 mesoporous electrodes in order to fabricate DSSCs with an iodide/triiodide-based electrolyte. Advanced photophysical characterizations, including charge extraction, transient photovoltage, and laser transient absorption spectroscopy experiments, combined with density functional theory modeling and computational investigations allow us to fully unravel the interfacial processes at the origin of the solar cell performances and to identify the limiting factors. A power conversion efficiency as high as 7% associated with a Jsc close to 19 mA cm−2 was obtained with one of the dyes, which is comparable to those of the best panchromatic organic dyes reported so far. We also demonstrate in this work that the Voc of the solar cells is linearly correlated to the dipolar moments of the oxidized dyes, the molecules possessing larger dipoles leading to the highest Voc value

Assessment on power systems non-deterministic state estimation algorithms

Publisher Copyright: © 2022 Elsevier B.V.Power systems are operated in a deterministic way. However, the increase in uncertainties (caused by measurement and communication errors or the absence of complete knowledge of the measured quantity) requires algorithms capable of assessing randomness in real-time monitoring and operation of energy management systems. Among them, state estimation is a fundamental element that provides complete and reliable information about the current network state. This paper offers a review of non-deterministic algorithms, used to assess the randomness caused by the uncertainties in power system state estimation. Depending on the uncertainty modeling method, different static and dynamic non-deterministic state estimation algorithms for transmission and distribution systems are reviewed. Also, four of the most relevant algorithms are implemented and results are compared for distribution networks. The relevance of such models, as well as their motivation, are addressed.The authors would like to thank HUBBELL INC., USA, TECNALIA, Basque Research and Technology Alliance (BRTA), Spain and University of the Basque Country (UPV/EHU), Spain for their valuable contributions.Peer reviewe

LINEAR STATE ESTIMATION IN DISTRIBUTION SYSTEMS USING SMART METER DATA

Publisher Copyright: © The Institution of Engineering and Technology 2023.The new generation of smart meters can provide valuable information. “New generation” smart meters provide voltage magnitude and apparent power measurements. In addition, voltage angle measurements referenced to the substation can be added. The aim of this paper is to formulate a state estimation algorithm for power distribution system, using apparent power, voltage angle and voltage magnitude measurements at low voltage residential customers. The research is focused on the American distribution system, which ranges from medium-voltage substations to low-voltage consumers. The objective is to determine the state of a distribution network, using only measurements provided by smart meters. Simulations performed on an EPRI test network section show that the voltages in MV can be estimated from smart meter measurements.Peer reviewe

Adaptive Reclosing Technique Using Variational Mode Decomposition Algorithm in BESS-Based Microgrid

This study introduces a novel adaptive technique to accelerate the process of reclosing in a Battery Energy Storage System (BESS)-based microgrid system to provide uninterrupted power supply (UPS). Two different methodologies, Fault Current Contribution Ratio (FCCR) and Variational Mode Decomposition (VMD) are used to implement the proposed technique. First, the FCCR between the healthy and faulty phases is estimated in the relay after the occurrence of the transient. In the next stage, exact fault occurrences and clearance instances are detected using the VMD technique. The exact detection of fault clearance time will help reduce the conventional outage time. This will reduce the unwanted burden on the BESS as it can be used adaptively during the fault only. The comparative assessment is done to show the efficacy of the proposed reclosing method. The proposed technique will also help distinguish faults from switching operations. The performance of the proposed method is validated through a modified IEEE 13-bus BESS-based microgrid architecture. The EMTDC/PSCAD software is used for simulation. The algorithms are developed on the MATLAB platform. Real-time test results are also provided for the signals obtained from the Smart Grid Technology Laboratory (SGTL) lab setup. The results prove the efficacy of the proposed technique

Minimization of Carrier Losses for Efficient Perovskite Solar Cells through Structural Modification of Triphenylamine Derivatives

Three hole transport materials (HTMs) based on a substituted triphenylamine moiety have been synthesized and successfully employed in triple-cation mixed-halide PSCs, reaching efficiencies of 19.4 %. The efficiencies, comparable to those obtained using spiro-OMeTAD, point them out as promising candidates for easily attainable and cost-effective alternatives for PSCs, given their facile synthesis from commercially available materials. Interestingly, although all these HTMs show similar chemical and physical properties, they provide different carrier recombination kinetics. Our results demonstrate that is feasible through the molecular design of the HTM to minimize carrier losses and, thus, increase the solar cell efficiencies

Visible and near-infrared organic photosensitizers comprising isoindigo derivatives as chromophores: synthesis, optoelectronic properties and factors limiting their efficiency in dye solar cells

The development of ruthenium-free organic photosensitizers showing panchromatic absorption up to the near-infrared (NIR) region for application in dye-sensitized solar cells (DSSCs) is still scarce. Among the sensitizers with absorption beyond 700 nm and developed for DSSCs, only zinc-phthalocyanine and boron-dibenzopyrromethene-based dyes have been able to reach efficiencies as high as 6%. Here we report metal-free organic dyes based on isoindigo, thieno-isoindigo or benzo-thieno-isoindigo chromophores that absorb in the UV-visible and NIR spectral range up to 900 nm. These molecules, that exhibit purple, blue, or green hues, were used to sensitize TiO2 mesoporous electrodes in order to fabricate DSSCs with an iodide/triiodide-based electrolyte. Advanced photophysical characterizations, including charge extraction, transient photovoltage, and laser transient absorption spectroscopy experiments, combined with density functional theory modeling and computational investigations allow us to fully unravel the interfacial processes at the origin of the solar cell performances and to identify the limiting factors. A power conversion efficiency as high as 7% associated with a Jsc close to 19 mA cm−2 was obtained with one of the dyes, which is comparable to those of the best panchromatic organic dyes reported so far. We also demonstrate in this work that the Voc of the solar cells is linearly correlated to the dipolar moments of the oxidized dyes, the molecules possessing larger dipoles leading to the highest Voc value

Towards Holistic Power Distribution System Validation and Testing – An Overview and Discussion of Different Possibilities

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