ORCID Profile
0000-0002-9877-2097
Current Organisations
Albert-Ludwigs-Universität Freiburg
,
Fraunhofer-Institut für Solare Energiesysteme
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: IEEE
Date: 05-2008
Publisher: IEEE
Date: 05-2008
Publisher: IOP Publishing
Date: 10-2012
Abstract: Modelling of solar cells today is general practice in research and widely-used in industry. Established modelling software is typically limited to one dimension and/or to small scales. Additionally, novel effects, like, e.g., the use of diffractive structures or luminescent materials, are not established. In this paper we discuss how the combination of different modelling techniques can be used to overcome these limitations. In this context two ex les are presented. The first ex le concerns the combination of the open source simulation software PC1D with circuit modelling to investigate the effect of local shunts on the global characteristics of a silicon wafer solar cell. For the investigated ex le (4.5 cm 2 cell area) we find that a local point shunt reduces the solar cell efficiency by 4% relative. The second ex le concerns the modelling of diffractive gratings for thin silicon wafer solar cells. For this purpose, we use the rigorous coupled wave analysis to simulate Sentaurus technical computer-aided design (TCAD) is combined with the rigorous coupled wave analysis, a method to solve Maxwell's equations for periodic structures. Here we show that a grating can be used to improve the absorption in a thin silicon wafer solar cell considerably.
Publisher: Authorea, Inc.
Date: 02-08-2023
DOI: 10.22541/AU.169099390.02971297/V1
Abstract: As the efficiency of perovskite silicon tandem solar cells is increasing, the upscaling for industrial production is coming into focus. Spatially resolved, quantitative, fast, and reliable contactless measurement techniques are demanded for quality assurance and to pinpoint the cause of performance losses in perovskite silicon tandem solar cells. In this publication we present a measurement method based on spectrally integrated photoluminescence (PL) imaging to extract subcell-selective implied open-circuit ( i V oc ) images from monolithic perovskite silicon tandem solar cells. We validate the approach using spectrally resolved absolute PL measurements based on an integrating sphere for the perovskite top cell and PL-calibrated carrier lifetime images for the silicon bottom cell. Additionally, V oc measurements of solar cells with low contact losses are used to validate the new measurement technique. We find a good agreement of the i V oc images with the validating measurements with a maximum deviation of well below 1 % compared to the validation measurements.
Publisher: AIP Publishing
Date: 23-06-2008
DOI: 10.1063/1.2945287
Abstract: In order to utilize the full potential of solar cells fabricated on n-type silicon, it is necessary to achieve an excellent passivation on B-doped emitters. Experimental studies on test structures and theoretical considerations have shown that a negatively charged dielectric layer would be ideally suited for this purpose. Thus, in this work the negative-charge dielectric Al2O3 was applied as surface passivation layer on high-efficiency n-type silicon solar cells. With this front surface passivation layer, a confirmed conversion efficiency of 23.2% was achieved. For the open-circuit voltage Voc of 703.6mV, the upper limit for the emitter saturation current density J0e, including the metalized area, has been evaluated to be 29fA∕cm2. This clearly shows that an excellent passivation of highly doped p-type c-Si can be obtained at the device level by applying Al2O3.
Publisher: Research Square Platform LLC
Date: 21-06-2022
DOI: 10.21203/RS.3.RS-1767937/V1
Abstract: While perovskite photovoltaic (PV) devices are on the verge of their commercialization, promising methods to recycle or remanufacture fully-encapsulated perovskite solar cells (PSCs) and modules are still missing. Through detailed life-cycle assessment shown in this work, we identify that the majority of the greenhouse gas emissions can be reduced by re-using the glass substrate and parts of the PV cells. Based on these analytical findings, we develop a novel thermally-assisted mechanochemical approach to remove the encapsulants, the electrode and the perovskite absorber, allowing to re-use most of the device constituents for remanufacturing PSCs, which recovered nearly 90% of their initial performance. This remanufacturing strategy allows to save up to 33% of the module’s global warming potential. Finally, we demonstrate that the CO 2 -footprint of these remanufactured devices can become less than 30g/kWh, which is the value for state-of-the-art c-Si PV modules and can even reach 15g/kWh assuming a similar lifetime
Publisher: AIP Publishing
Date: 15-11-2007
DOI: 10.1063/1.2812698
Abstract: Boron-doped silicon wafers implanted with low doses of manganese have been analyzed by means of deep-level transient spectroscopy (DLTS), injection-dependent lifetime spectroscopy, and temperature-dependent lifetime spectroscopy. While DLTS measurements allow the defect levels and majority carrier capture cross sections to be determined, the lifetime spectroscopy techniques allow analysis of the dominant recombination levels and the corresponding ratios of the capture cross sections. Interstitial manganese and manganese-boron pairs were found to coexist, and their defect parameters have been investigated. In good agreement with the literature, this study identifies the defect level of manganese-boron pairs to be located in the lower half of the band gap at an energy level of Ev+0.55 eV with a majority carrier capture cross section of σp=3.5×10−13 cm2. The capture cross-section ratio was found to be k=σn∕σp=6.0. This implies that the previously unknown minority carrier capture cross section is σn=2.1×1012 cm2. Concerning the defect related to interstitial manganese, this study identifies the most recombination-active level to be located in the upper half of the band gap at EC−0.45 eV with a corresponding ratio of the capture cross sections of k=9.4. In addition, the temperature-dependent association time constant of manganese-boron pairs is determined to be τassoc,Mn=8.3×105 K−1 cm−3(T∕Ndop)exp(0.67 eV∕kBT) and found to differ from that for iron by a factor of 3 at room temperature, allowing this association time constant to be used as a fingerprint for a possible contamination with manganese. Also, the diffusion coefficient of interstitial manganese in silicon is determined from these experiments in a temperature range from 70 to 120 °C. It can be represented by the expression DMn=6.9×10−4 cm2 s−1 exp(−0.67 eV∕kBT).
No related grants have been discovered for Stefan W. Glunz.