A European proficiency test on thin film tandem photovoltaic devices

A round robin proficiency test RR PT on thin film multi junction MJ photovoltaic PV cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions STC . Three cells were a Si amp; 956;c Si tandem PV devices, each of which had a different short circuit current ratio between the top junction and the bottom one; the remaining two cells were single junction PV devices made with material representative of the individual junctions in the MJ cells. The RR PT s main purpose was to assess the capability of the participating laboratories, in terms of employed facilities and procedures, to test MJ PV devices. Therefore, participant

Effects of thyme and rosemary essential oils on the growth of two aflatoxigenic Aspergillus flavus strains

In this study, antifungal effects of thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) essential oils (EOs) on two aflatoxigenic Aspergillus flavus strains (MAM-200682 and MAM-2006113) previously isolated from hazelnut were investigated. Five different concentration of the EOs (500, 250, 125,62 and 31 µL/mL) were prepared in methanol. Minimal inhibitory concentration (MIC) values of the thyme and rosemary EOs against two cultures were determined as 31 and 125 µL/mL, respectively. 250 µL/mL of thyme EO on A. flavus MAM-200682, and 125 µL/mL of thyme EO and 500 µL/mL of rosemary EO on A. flavus MAM-2006113 had fungicidal effect. Fungal growth was almost completely inhibited after 90 min application of thyme EO concentrations (250 and 125 µL/mL). Rosemary EO caused slight growth inhibition. Thyme EO has the most fungistatic and fungicidal effect against aflatoxigenic A. flavus strains. These results indicated that the thyme and rosemary EOs could be used as natural antimicrobial agents against aflatoxigenic A. flavus in the food preservation practices

Structural characterization of intrinsic a-Si:H thin films for silicon heterojunction solar cells

We have utilized ex-situ spectroscopic ellipsometry and HRTEM to characterize the optical and structural properties of intrinsic a-Si:H thin layer that plays a key role for the improvement of the open circuit voltage in silicon heterojunction solar cells. Intrinsic a-Si:H films were deposited on (100) p-type CZ silicon wafers by using Plasma Enhanced Chemical Vapor Deposition (PECVD) technique at 225 degrees C substrate temperature and deposition time ranges from 15 s to 1800 s. Observed changes in the imaginary part of pseudo dielectric constant, epsilon(2), of c-Si spectrum with two peaks centered in 3.4 eV and 4.2 eV to a-Si:H which has an intermediate spectrum with a soft peak at about 4.2 eV has been analyzed with using effective medium approximation model

Study of the a-Si:H/c-Si Heterointerface by Ex-Situ Spectroscopic Ellipsometry, Infrared Spectroscopy, and Solar Cell Modeling

The interface formation between plasma-enhanced chemical vapor-deposited (PECVD) silicon thin films and H-terminated, p-type c-Si was investigated. The formation of hydrogenated amorphous silicon (a-Si:H), epitaxial Si, and mixed phase Si was detected through spectroscopic ellipsometry (SE) and high-resolution transmission electron microscopy (HRTEM). The evolution of the hydrogen content and hydrogen bonding configurations in the films were monitored by attenuated total reflection infrared spectroscopy (FTIR-ATR). The dependence of the hydrogen binding configuration on the film morphology was observed. Even with an observed epitaxial layer in the structure of the intrinsic a-Si:H, a silicon heterojunction (SHJ) solar cell with 9.2% efficiency was obtained, which is the largest-active-area (72 cm(2)) SHJ cell on p-type c-Si. The numerical simulation tool AFORS-HET was used to model the layers and interface properties of the cell. The simulation results were consistent with the experimental results, demonstrating the importance of interface defect passivation in SHJ solar cells

Structural and Interfacial Properties of Large Area n-a-Si:H/i-a-Si:H/p-c-Si Heterojunction Solar Cells

Large area (72 cm(2)) doping inversed HIT solar cells (n-a-Si:H/i-a-Si:H/p-c-Si) were investigated by High Resolution Transmission Electron Microscopy (HR-TEM), Spectroscopic Ellipsometry (SE), Fourier Transform Infrared Attenuated Total Reflection spectroscopy (FTIR-ATR) and current-voltage (I-V) measurement. Mixture of microcrystalline and amorphous phase was identified via HR-TEM picture at the interface of i-a-Si:H/p-c-Si heterojunction. Using multilayer and Effective Medium Approximation (EMA) to the SE data, excellent fit was obtained, describing the evolution of microstructure of a-Si: H deposited at 225 degrees C on p-c-Si. Cody energy gap with combination of FTIR-ATR analyses were consistent with HRTEM and SE results in terms of mixture of microcrystalline and amorphous phase. Presence of such hetero-interface resulted poor open circuit voltage, V-oc, of the fabricated solar cell devices, determined by I-V measurement under 1 sun. Moreover, V-oc was also estimated from dark I-V analysis, revealing consistent V-oc values. Efficiencies of fabricated cells over complete c-Si wafer (72 cm2) were calculated as 4.7 and 9.2 %. Improvement in efficiency was interpreted due to the back surface cleaning and selecting aluminum/silver alloy as front contact

A European proficiency test on thin-film tandem photovoltaic devices

A round-robin proficiency test (RR PT) on thin-film multi-junction (MJ) photovoltaic (PV) cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions (STC). Three cells were a-Si/μc-Si tandem PV devices, each of which had a different short-circuit current ratio between the top junction and the bottom one; the remaining two cells were single-junction PV devices made with material representative of the individual junctions in the MJ cells. The RR PT’s main purpose was to assess the capability of the participating laboratories, in terms of employed facilities and procedures, to test MJ PV devices. Therefore, participants were requested to perform STC measurements of all cells according to their own procedure, which might not include external quantum efficiency measurements. The European Solar Test Installation (ESTI) of the Joint Research Centre (JRC) provided the reference calibrations against which the participants’ results are compared. ESTI made also a verification of the cells performance at STC at the end of the RR PT, in order to allow a comparison between the initial stable state at which the cells were calibrated (just before circulation) and the one they had reached at the end of the RR PT. The overall results of the RR PT are here presented and discussed together with some aspects of MJ PV testing that emerged as not adequately applied or largely missing. Their full implementation is expected to improve the consistency of future results.JRC.C.2-Energy Efficiency and Renewable

Cover Image

The cover image is based on the Research Article A European proficiency test on thin‐film tandem photovoltaic devices by Elena Salis et al., https://doi.org/10.1002/pip.3322. The cover image has been prepared in response to an invitation by the journal to compete for the cover of the issue that includes the paper.JRC.C.2-Energy Efficiency and Renewable

European thin film tandem device proficiency test practical outcomes and preliminary results

Within the European FP7 project CHEETAH, a thin film tandem solar cell round robin proficiency test was conducted between 13 testing laboratories, plus the European Solar Test Installation ESTI of the European Commission s Joint Research Centre as reference laboratory. The purpose of this RR was to compare testing facilities and procedures of the involved partners against the reference measurement by ESTI. In total, five cells were measured. Three tandem devices a Si H c Si and a single junction device representing the top a Si H and the bottom c Si cells, respectively, were provided by one partner. All cells with active area of 1 cm2 were mounted in a standardised housing with connection sockets for I V measurements and a Pt 100 temperature sensor. The cells were initially stabilised and calibrated at ESTI and afterwards circulated. The characterisation was done by I V measurements at Standard Test Conditions and EQE measurements. ESTI checked and re calibrated the cells at the end of the RR before and after further stabilization. Here we report on some preliminary I V measurement results. A number of acquired or conversely still necessary improvements are discussed for the organisational point of view along with some measurement requirements that are still missing or that are not sufficient at many participating laboratorie