Author
Francesca Ferrazza
Bio: Francesca Ferrazza is an academic researcher. The author has contributed to research in topics: Carrier lifetime & Silicon. The author has an hindex of 6, co-authored 6 publications receiving 1162 citations.
Papers
More filters
TL;DR: In this paper, a hexagonally symmetric honeycomb surface texture was used to reduce reflection loss in multicrystalline silicon solar cells and increase the cell's effective optical thickness.
Abstract: Multicrystalline silicon wafers, widely used in commercial photovoltaic cell production, traditionally give much poorer cell performance than monocrystalline wafers (the previously highest performance laboratory devices have solar energy conversion efficiencies of 186% and 240%, respectively) A substantially improved efficiency for a multicrystalline silicon solar cell of 198% is reported together with an incremental improvement in monocrystalline cell efficiency to 244% The improved multicrystalline cell performance results from enshrouding cell surfaces in thermally grown oxide to reduce their detrimental electronic activity and from isotropic etching to form an hexagonally symmetric “honeycomb” surface texture This texture reduces reflection loss as well as substantially increasing the cell’s effective optical thickness by causing light to be trapped within the cell by total internal reflection
977 citations
TL;DR: In this article, the carrier lifetimes of n-type multicrystalline silicon (mc-Si) grown by directional solidification and subjected to phosphorus gettering were measured for relatively lowly doped, 2-3 cm, wafers.
Abstract: Exceptionally high minority carrier lifetimes have been measured in n-type multicrystalline silicon (mc-Si) grown by directional solidification and subjected to phosphorus gettering. The highest effective lifetimes, up to 1.6 ms averaged over several grains and 2.8 ms within some of them, were measured for relatively lowly doped, 2–3 Ωcm, wafers. The lifetime was found to decrease for lower resistivities, still reaching 500 μs for 0.9 Ωcm and 100 μs for 0.36 Ωcm. Several important findings are reported here: (i) achievement of carrier lifetimes in the millisecond range for mc-Si, (ii) effectiveness of phosphorus gettering in n-type mc-Si, and (iii) demonstration of good stability under illumination for n-type mc-Si.
93 citations
TL;DR: In this paper, the electronic quality of multicrystalline material produced by directional solidification has been evaluated by means of photoconductance techniques, and very high minority carrier lifetimes, in the vicinity of 200 μs, have been measured in p-type 1.5 Ω cm material that had received a phosphorus diffusion gettering treatment.
Abstract: The electronic quality of multicrystalline material produced by directional solidification has been evaluated by means of photoconductance techniques. Very high minority carrier lifetimes, in the vicinity of 200 μs, have been measured in p-type 1.5 Ω cm material that had received a phosphorus diffusion gettering treatment. The measurements correspond to an effective lifetime averaged over an area of 3 cm2 that includes several grain boundaries and reflects the combined bulk, grain boundary and surface recombination mechanisms. The high lifetime (15 μs) also obtained in low resistivity 0.2 Ω cm wafers has allowed the fabrication of solar cells with an open-circuit voltage of 657 mV (AM1.5 G, 100 mW/cm2, 25 °C), probably the highest ever reported for multicrystalline silicon.
52 citations
TL;DR: In this article, the effect of phosphorus gettering on cast multicrystalline silicon solar cell substrates from central and end regions of two different ingots was measured to determine the minority carrier lifetimes.
Abstract: Minority carrier lifetimes were measured to determine the effect of phosphorus gettering on cast multicrystalline silicon solar cell substrates from central and end regions of two different ingots. One ingot exhibited visibly inferior crystallographic structure and, correspondingly, showed lower lifetimes. Wafers from the bottom region of both ingots improved significantly after gettering, whilst those from the top experienced no lifetime increase. Defect etching revealed that the wafers from the top had very high dislocation densities (>106 cm−2), whereas wafers from the bottom had low dislocation densities (104 cm−2). Novel cross-contamination experiments showed that all top and bottom wafers contained high concentrations of mobile (and hence getterable) impurities in comparison to central regions, irrespective of dislocation density. For the case of the highly dislocated samples, a sufficient number of recombination centers remains to prevent an increase in the lifetime, even after the mobile impurities have been extracted through gettering. Wafers from central regions had both moderate dislocation densities and low concentrations of out-diffusible impurities. Their lifetimes increased after gettering up to a more evenly distributed limit imposed by the crystallography, which was found to be ingot and region dependent.
50 citations
18 May 2003
TL;DR: In this article, an investigation of n-type multicrystalline silicon grown by directional solidification has produced several important findings: i) demonstration of effective phosphorus gettering; ii) achievement of minority carrier lifetimes above one millisecond; iii) verification of good stability under illumination.
Abstract: An investigation of n-type multicrystalline silicon grown by directional solidification has produced several important findings: i) demonstration of effective phosphorus gettering; ii) achievement of minority carrier lifetimes above one millisecond; iii) verification of good stability under illumination. The lifetimes after gettering show a strong dependence on doping: 1.6 ms for 2.3 /spl Omega/cm, 500 /spl mu/s for 0.9 /spl Omega/cm and 100 /spl mu/s for 0.36 /spl Omega/cm, respectively. Lifetime mapping by infrared carrier density imaging has revealed a large surface variability of this parameter, which is detrimental for large area devices. A minor degradation of the lifetime after light exposure has been observed for the highest lifetime regions, while other wafers and regions remained essentially stable.
14 citations
Cited by
More filters
TL;DR: Green et al. as mentioned in this paper presented consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules, and guidelines for inclusion of results into these tables are outlined and new entries since July 2014 are reviewed.
Abstract: Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2014 are reviewed. URI: http://onlinelibrary.wiley.com/doi/10.1002/pip.2573/pdf [1] Authors: GREEN Martin A. EMERY Keith HISHIKAWA Y. WARTA W. DUNLOP Ewan Publication Year: 2015 Type: Articles in Journals
2,511 citations
TL;DR: A comprehensively and systematically review the leading candidate materials, present the limitations of each system, and analyze how these limitations can be overcome and overall cell performance improved.
Abstract: Recent developments in photovoltaic materials have led to continual improvements in their efficiency. We review the electrical characteristics of 16 widely studied geometries of photovoltaic materials with efficiencies of 10 to 29%. Comparison of these characteristics to the fundamental limits based on the Shockley-Queisser detailed-balance model provides a basis for identifying the key limiting factors, related to efficient light management and charge carrier collection, for these materials. Prospects for practical application and large-area fabrication are discussed for each material.
1,537 citations
TL;DR: In this article, the authors presented flexible organic solar cells that are less than 2 μm thick, have very low specific weight and maintain their photovoltaic performance under repeated mechanical deformation.
Abstract: Organic solar cells are promising for technological applications, as they are lightweight and mechanically robust. This study presents flexible organic solar cells that are less than 2 μm thick, have very low specific weight and maintain their photovoltaic performance under repeated mechanical deformation.
1,451 citations
1,210 citations
TL;DR: The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits, and recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photov electricity generation.
Abstract: The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.
1,177 citations