Floating sensor platform for the monitoring of water quality in urban and white-water environments

In the present paper the project of an embeddedsolution for the realization of a floating sensor platform for themonitoring of the water and ambient quality in a flowing waterenvironment is described. First results regarding the monitoringof the water conductivity and the ambient noise level underharsh environmental conditions in a karstic river and in the finalpart of a river going towards the Mediterranean Sea arepresented. It is further discussed how this kind of system can bemodified in order to serve as urban waterway multisensoryplatform, adding important features like connectivity, energyharvesting and determination of the platform position.

Photovoltaic Behavior of V 2 O 5 /4H-SiC Schottky Diodes for Cryogenic Applications

The photovoltaic behavior of (divanadioum pentoxide)/(4H polytype silicon carbide) Schottky diodes under ultraviolet illumination and down to 28K is investigated. In addition to their high stability, by using the thermionic model the analysis allows to confirm the predictability of performances at cryogenic temperatures, such as the high light/dark current ratio and the dependence of the photocurrent and open circuit voltage on material parameters. Because of the low-annealing temperature, this structure is shown to be a good candidate for solar-blind photodetectors in the UV spectral range of spatial and terrestrial cryogenic applications

evidence of bipolar resistive switching memory in perovskite solar cell

In hybrid inorganic-organic perovskite solar cells a very stable bipolar resistive switching behavior in the dark current-voltage characteristics at low-voltages has been observed. The possible use of the solar cell as an electrical memory with a moderate on-off contrast but very good stability over a prolonged time has been suggested. The reversible behavior and the long dynamics during the write/erase processes indicate that the physical mechanism behind the switching is related to polarization effects. A detailed analysis of the charge carrier trapping/detrapping, transport, and recombination mechanisms has been performed by taking the ion migration and the consequent charge carrier accumulation within the device into account. The charge transport during the write operation can be described by space-charge-limited conduction process. The formation and subsequent interruption of conducting pathways due to ion migration have been identified as the main cause of the resistive switching within the perovskite material. The strong interaction between the ion movement and the electron transport enables the operation of the perovskite solar cell also as a non-volatile memory

Proton‐Radiation Tolerant All‐Perovskite Multijunction Solar Cells

Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781Funder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266Funder: European Union's Horizon 2020Abstract: Radiation‐resistant but cost‐efficient, flexible, and ultralight solar sheets with high specific power (W g−1) are the “holy grail” of the new space revolution, powering private space exploration, low‐cost missions, and future habitats on Moon and Mars. Herein, this study investigates an all‐perovskite tandem photovoltaic (PV) technology that uses an ultrathin active layer (1.56 µm) but offers high power conversion efficiency, and discusses its potential for high‐specific‐power applications. This study demonstrates that all‐perovskite tandems possess a high tolerance to the harsh radiation environment in space. The tests under 68 MeV proton irradiation show negligible degradation (22%. Using high spatial resolution photoluminescence (PL) microscopy, it is revealed that defect clusters in GaAs are responsible for the degradation of current space‐PV. By contrast, negligible reduction in PL of the individual perovskite subcells even after the highest dose studied is observed. Studying the intensity‐dependent PL of bare low‐gap and high‐gap perovskite absorbers, it is shown that the VOC, fill factor, and efficiency potentials remain identically high after irradiation. Radiation damage of all‐perovskite tandems thus has a fundamentally different origin to traditional space PV

Proton Radiation Hardness of Perovskite Tandem Photovoltaics.

Monolithic [Cs0.05(MA0. 17FA0. 83)0.95]Pb(I0.83Br0.17)3/Cu(In,Ga)Se2 (perovskite/CIGS) tandem solar cells promise high performance and can be processed on flexible substrates, enabling cost-efficient and ultra-lightweight space photovoltaics with power-to-weight and power-to-cost ratios surpassing those of state-of-the-art III-V semiconductor-based multijunctions. However, to become a viable space technology, the full tandem stack must withstand the harsh radiation environments in space. Here, we design tailored operando and ex situ measurements to show that perovskite/CIGS cells retain over 85% of their initial efficiency even after 68 MeV proton irradiation at a dose of 2 × 1012 p+/cm2. We use photoluminescence microscopy to show that the local quasi-Fermi-level splitting of the perovskite top cell is unaffected. We identify that the efficiency losses arise primarily from increased recombination in the CIGS bottom cell and the nickel-oxide-based recombination contact. These results are corroborated by measurements of monolithic perovskite/silicon-heterojunction cells, which severely degrade to 1% of their initial efficiency due to radiation-induced recombination centers in silicon.F.L. acknowledges financial support from the Alexander von Humboldt Foundation via the Feodor Lynen program and thanks Prof. Sir R. Friend for supporting his Fellowship at the Cavendish Laboratory. This work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (HYPERION, grant agreement number 756962). M.J, A.A.A., E.K., and S.A. acknowledge financial support from the German Federal Ministry of Education and Research (BMBF) via program “Materialforschung für die Energiewende” (grant no. 03SF0540), by the German Federal Ministry for Economic Affairs and Energy (BMWi) through the ‘PersiST’ project (Grant No. 0324037C). T.B. C.A.K. and R.S. acknowledge funding by BMWi through the speedCIGS (grant no. 0324095E) and EFFCIS project (grant no. 0324076D). D.K. and M.C. acknowledge financial support from the Dutch Ministry of Economic Affairs, via The Top-consortia Knowledge and Innovation (TKI) Program ‘‘Photovoltaic modules based on a p-i-n stack, manufactured on a roll-to-roll line featuring high efficiency, stability and strong market perspective’’ (PVPRESS) (TEUE118010) and “Bridging the voltage gap” (BRIGHT) (1721101). K. F. acknowledges the George and Lilian Schiff Fund, the Engineering and Physical Sciences Research Council (EPSRC), the Winton Sustainability Fellowship, and the Cambridge Trust for funding. S.D.S. acknowledges the Royal Society and Tata Group (UF150033). The authors acknowledge the EPSRC for funding (EP/R023980/1). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 841265. A.R.B. acknowledges funding from a Winton Studentship, Oppenheimer Studentship, and funding from the Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Centre in Photovoltaics (CDT-PV). K.G. acknowledges the Polish Ministry of Science and Higher Education within the Mobilnosc Plus program (Grant No. 1603/MOB/V/2017/0)

Noise spectroscopy of perovskites

Hybrid perovskite solar cells with different crystalline grain size have been characterized by conventional techniques and additionally by low-frequency electrical noise spectroscopy. A clear correlation between the morphological structure of the perovskite grains, the energy disorder of the defect states, and the device performance has been demonstrated. In addition, the analysis of the temperature dependence of the noise amplitude has been also used to clearly identify the low-temperature transition between the orthorhombic and the tetragonal phases in perovskite solar cells and to extract important electronic parameters for both crystalline configurations

Very simple and sensitive low-cost PEDOT:PSS temperature and breathing sensor

During COVID-19 lock-down and consequently difficult access to research and teaching laboratories a very simple temperature sensor has been fabricated at home in the kitchen, demonstrating to the students the simplicity of basic organic electronic device preparation. To our great surprise the extremely simple fabricated flexible temperature sensor, with a PEDOT: PSS thin film deposited between coplanar contacts, realized just by a graphite pencil writing on commercial copy machine paper, exhibited a very high sensitivity, exceeding so far reported literature values and after a burn-in procedure also a very stable and perfectly ohmic electrical characteristics has been obtained. It could be shown that the PEDOT: PSS based sensors is about 5 times more sensitive with respect to temperature changes as compared to the drawn graphite based contacts alone. Reproducibility of the simple fabrication technique has been demonstrated with a second sensor of the same type. In this case a temperature calibration has been done and a possible application as sensitive breathing sensor has been demonstrated

Influence of the Contact Metallization on the Characteristics of Resistive Temperature Sensors Based on EPOXY/MWCNT Composites

The influence of different contact metallization materials and geometries on stability, sensitivity and linearity of epoxy/carbon nanotube based temperature sensors has been investigated. In our experiments, we found a perfect linear current-voltage characteristic and a stable conductance-temperature characteristics in the case of the sensor structures with the evaporated niobium contacts and a non-linear and noisy current-voltage characteristic with hysteresis in the case of the copper wire contacts. After a burn-in procedure, however, we could partially stabilize the electrical characteristics of the copper-wire contact based devices. However, in the latter case, even if a higher sensor sensitivity has been measured, the temperature sensing characteristics remained rather noisy a and an acceptable long-term stability could not be achieved

Application of a Bio-Nanocomposite Tissue as an NIR Optical Receiver and a Temperature Sensor

The application of a type of bio-nano tissue, consisting of tobacco cells and multiwalled carbon nanotubes, as a sensitive near-infrared region (NIR) bolometer operating at room temperature was investigated. An electrical resistor-type sensor was fabricated by the evaporation of lateral gold contacts. A very low dark conductivity was achieved by a high-voltage treatment of a strongly conducting nanotube network. Although before the treatment the electrical transport was dominated by the percolative transport in the nanotube network, after the voltage stress the electronic transport in the low-conductivity tissue was controlled only by the intrinsic electrical properties of the biological matrix. In this latter case, the conductivity was extremely temperature and humidity dependent. However, on operating the sensor tissue in a small temperature window around room temperature, the change in humidity could be neglected. Under these conditions, the multifunctional device functioned as a very high sensitivity temperature sensor with a temperature coefficient of resistance of more than −20%/K. Sensitive bolometer operation with a very good signal-to-noise ratio was demonstrated by irradiation of the tissue with low-power LEDs in the near-infrared range between 780 and 1720 nm

New biodegradable nano-composites for transient electronics devices

A comparison between transient energy storage systems based on a gelatin composite with graphene flakes and graphene oxide layers has been done. Energy storage devices, based on the proposed new materials have higher values of the surface capacitance than those measured for energy storage devices based on activated carbon. As evidenced, both the composites enable the realization of energy sources that can supply a stable bias voltage in time. The biopolymer acts both as solid electrolyte and as binder for holding together the filler and the water-glycerol molecules. In addition, the use of the graphene oxide as filler within the gelatin matrix leads to a major increase of the mechanical stability of the prepared blends