The purpose of the work is to find an appropriate flexible material to replace commonly used transparent conductive oxides (TCO) in photovoltaic (PV) emitter electrode applications. Authors show the alternative, potential possibility of using PEDOT conductive polymer as transparent emitter contacts for thin-film, flexible photovoltaic structures. The vast majority of contacts made of TCO layers, dominantly indium tin oxide ITO, are electrically unstable under the influence of mechanical stresses [1,2,3]. This drawback inhibits their usage in flexible devices, such as solar cells. The need of the development in the field of flexible PV structures induces searching for new materials. Investigated transparent conductive layers (TCL) were made of organic compositions based on PEDOT polymer and their parameters were compared with equally measured parameters of carbon nanotube (CNT) layers, commercial ITO and AgHT ultra-thin silver layers. Transparent conductive layers based on PEDOT:PSS compound were deposited on flexible substrates by screen printing technique. The analysis of achieved results shows the broad spectrum of application possibilities for PEDOT layers.
In this paper, the results of the initial work on determining the photoelectric properties of graphene detector operating in a photoconductive mode are presented. Graphene is considered as a material for uncooled fast detectors. The investigation has been done by electrical and optical characterization. Two values of substrate resistivity have been used in the project – below 1 Ωcm and higher than 1.6 kΩcm. Measurements of detectors response to short, strong light pulses were conducted. Presented studies show that the use of high resistivity substrates is necessary to prevent capacitive shorting of the signal to the substrate, causing signal losses and increasing response time.
In this work, the influence of H2O, NaOH and propanol on properties of graphene layer placed on SiO2 has been investigated. These chemical particles are present during technological steps required for a device fabrication and may lead to significant changes of graphene properties. The investigation has been done by means of ab-initio simulation based on the DFT method. A MedeA-VASP package was used to investigate behavior of graphene layer in the vicinity of chemical compounds. Presented studies show that properties of graphene are significantly modified when particles of H2O and NaOH are captured in-between graphene layer and SiO2. Special attention should be paid to NaOH which, according to simulations, decays and modifies the properties of graphene layer.
KEYWORDS: Transducers, Ferroelectric polymers, Solar energy, Thin films, Capacitance, Thin film devices, Energy harvesting, Energy efficiency, Electronic circuits, Energy conversion efficiency
The paper presents the examination of modern flexible piezoelectric thin films made of PVDF (polyvinylidene
difluoride) in terms of their application in electromechanical transducers, a brief overview of available piezoelectric
materials and energy harvesting devices based on piezoelectric. In order to assess the usefulness of these films from the
perspective of described devices, the energy efficiency coefficient determined under the pulse excitation conditions was
taken into account. Normalized volumetric efficiency ratio allows to evaluate the commercially available flexible
piezoelectric films.
In the paper we report the results of investigation focused on conditions of the ohmic contacts formation on p-type non-implanted
4H-SiC substrates. Aluminum layers were deposited, photolithographically etched and annealed at
temperatures from 700 to 1000°C to obtain electrical contacts to SiC. On substrates annealed at temperatures 900 and
1000C the I-V characteristics confirmed ohmic type contacts formation. Lowest resistivity of fabricated contacts
calculated using Circular Transfer Line Model (CTLM) was 2.64·10-4 Ωcm2. TOF SIMS profiling and RDX analysis
were used to verify the microstructure of the Al/SiC interface. Ohmic contacts are characterized by an increased intensity
of Si2- ion emission, which are characteristic for silicon nanocrystals, with respect to the emission from the pure SiC.
This observation indicates that the ohmic nature of the received contacts can be affected by the presence of
nanocrystalline silicon contact area. Presence of the nanocrystalline silicon has been also confirmed by XRD analysis.
In this paper the specifics of FTTH (Fiber To The Home) networks in terms of requirements for optical fibers has been
presented. Optical fiber samples used in FTTH applications acquired from the worldwide leading manufacturers were
subjected to small diameter mandrel wraps tests. The detailed procedures of performed tests and the measurement results
has been presented.
A 2-D electrothermal model of thyristor structure with emitter shorts is presented. It is formed by three coupled submodels: electrical, heat transfer, and heat dissipation. The heat dissipation submodel takes into account heat generation caused by ohmic losses and recombination, as well as the inner heat transfers caused by thermoelectric effects. The results show how the presence of emitter shorts influences the work conditions inside the considered thyristor.
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