Dieses Forschungsprojekt wird von Australian Research Council durch die Verknüpfung mit Zuschuss CSG Solar Pty Ltd Rao Jing unterstützt erkennt ihr University of NSW Vizekanzler Postdoc-Stipendium. REM-Aufnahmen wurden von Jongsung Park der Verwendung des Geräts durch die Elektronenmikroskopie Unit der University of NSW gefasst hat.

1. Herstellung von polykristallinen Silizium-Solarzellen (Animation 3) <ol><li> Silicon Filmabscheidung <ol class="lalpha"><li> Bereiten Sie die Elektronenstrahlverdampfung Werkzeug gebacken wird bei ~ 100 ° C über Nacht, um die Basis Druck von &lt;3E-8 Torr erreichen. Speichern Sie die Probe auf die Heizung 150 ° C Standby-Temperatur. </li><li> Verwendung eines Substrats aus 5x5 cm 2 (oder 10 x 10 cm 2) Substratspezifität Borosilikatglas (Schott Borofloat33), 1,1 oder 3,3 mm dick, beschichtet mit ~ 80 nm Siliziumnitrid (hergestellt durch PECVD aus N 2 und SiH 4-Gemisch) hergestellt. </li><li> Blasen Sie die Oberfläche des Substrats mit trockenem Stickstoff, um Staub zu entfernen und ihn in einen Probenhalter. Entlüften Sie die Schleusen, laden Sie die Probe, pumpen die Schleuse bis auf den Druck &lt;1E5 Torr, und übertragen Sie die Probe in die Hauptkammer. Starten Sie die Heizung auf den Sollwert von 250 ° C Pumpe für etwa 20 min, wenn der Druck 8E-8 Torr oder weniger. </li><li> Überprüfen Sie, dass die DotierungQuelle und das Siliciumquellengas Verschlüsse davon geschlossen sind. Preset Dotierstoffquelle Temperaturen in den Standby-Temperaturen, dh die Phosphorquelle bei 700 ° C und Borquelle Temperatur bei 1250 ° C Sie E-Pistole und Schmelze Silizium in einem Tiegel durch langsames Erhöhen der E-Pistolenstrom. </li><li> Wenn die gewünschte Stromstärke erreicht (der letzten Kalibrierung: dieser Strom abhängig von der E-Pistole und die Si-Quelle variieren) zu verdampfen Siliziumschichten mit der erforderlichen Konzentration von P und B dotiert: 35 nm Emitter an 1E20 cm -3 P ; 2 ~ 3 um Absorber bei 5E15 cm -3 der B; 100 nm Back-Surface-Field (BSF) am 4E19 cm -3 von B. Die genauen Dotierstoffkonzentrationen werden durch die Zusammenführung bestimmter Si Abscheideraten erzielt werden, wie von Quartz Crystal-Monitor gemessen (QCM), die mit bestimmten Dotierstoffquelle Temperaturen, unter Verwendung von SIMS Kalibrierung Beziehungen etabliert. </li><li> Nach dem Verdunsten geschieht das Heizgerät ausschalten, abkühlen lassen die Probe für ~ 10 min. Transfer der Probe auf den Beladungsschleusenkammer, schließt das Gate-Ventil hat, den Ladesperre und Entladen der Probe mit dem Siliziumfilm. </li></ol></li><li> Kristallisation von Silizium Wenn die Probe 10x10 cm 2, kann es in vier 5x5 cm 2 Zellgröße Stücke geschnitten werden, bevor die Kristallisation. Legen Sie eine abgeschiedene Silizium auf Glas (Si-Film oben) auf einem Halter von aufgerauten und Siliziumnitrid beschichtet Schott Glas Robax (zu kleben) gemacht. Laden in einen mit Stickstoff gespülten Ofen vorgewärmt auf 200-300 ° C Rampe auf die Temperatur bis zu 600 ° C bei 3 bis 5 ° C / min und 30 h Tempern. Drehen des Ofens Heizung und Ofen abkühlen lassen natürlich auf ~ 200 ° C (2 ~ 3 Stunden) vor der Entlastung der Probe. Die Probe kann eine konkave Form durch das Silicium Schrumpfung während der Kristallisation. Es wird während der folgenden Rapid Thermal Processing zu glätten. </li><li> Dotandenaktivierung und Defektausheilung (RTA) Die Proben mit der kristallisierte Film auf einem Halter aus pyrolytischem Graphit und I aufoad einem schnellen thermischen Prozessor mit Argon gespült. Rampe die Temperatur bis 600 ° C bei 1 ° C / s, dann bis zu 1000 ° C bei 20 ° C / s, 1 min dann kühl halten Sie natürlich auf ~ 100 ° C und entladen. </li><li> Oberflächenoxid Entfernung Unmittelbar vor der Hydrierung das Oberflächenoxid auf Siliziumfilm bei der Kristallisation und RTA ausgebildet entfernt werden, um sicherzustellen, dass die blanken Silizium Folienoberfläche Wasserstoff ausgesetzt werden. Tauchen Sie den geglühten Probe in 5% HF-Lösung, bis der Silizium-Oberfläche verwandelt hydrophoben (30 ~ 100 s). Spülen mit VE-Wasser und trocknen Sie mit einem Stickstoff-Pistole. </li><li> Defect Passivierung Laden der Probe in eine Vakuumkammer mit dem Remote-Wasserstoff-Plasma-Quelle ausgestattet. Pumpe bis &lt;1E-4 Torr, erwärmen sich die Probe bis zu ~ 620 ° C, auf der Argon / Wasserstoff-Gemisch fließen drehen (50:150 sccm), Ansprechdruck 50-100 mTorr, starten Sie den Plasma-Quelle bei 3,5 kW die Mikrowellenleistung und den Prozess für ~ 10 min. Drehen Sie die Heizung aus, während maintaligt ist, das Plasma für weitere 10-15 min, bis die Temperatur fällt unter 350 ° C, bevor das Plasma aus und Stoppen der Gasströmung. Entlasten Sie die Probe, wenn die Temperatur unter 200 ° C </li><li> Zell-Metallisierung Handy Metallisierung in einer Reihe von aufeinanderfolgenden photolithographische Strukturierung, Al-Film Deposition und Ätzschritte, die im Detail in 11 beschrieben durchgeführt. Der letzte Zelle sieht aus wie in der letzten Folie of Animation 3 dargestellt. Eine Nahaufnahme des metallisierten Zelle ist in Abb. 1 dargestellt. </li><li> Messen Sie EQE der metallisierte Zelle. </li></ol> 2. Die Herstellung der Nanopartikel Plasmonische Ag (Animation 4) <ol><li> Brennen der metallisierte Zelloberfläche mit trockenem Stickstoff zur Entfernung von Staub und Laden der Probe in einem thermischen Verdampfer mit einem W Boot mit Ag Granulat (0,3-0,5 g) gefüllt. Abpumpen der Verdampferkammer mit der Basis Druck von 2 ~ 3E-5 Torr. QCM Programm mit Parametern für Ag: Dichte 10,50und Z-Verhältnis 0,529. </li><li> Stellen Sie sicher, dass die Probe Shutter geschlossen ist, drehen Sie das W Heizung für Boote auf und erhöhen den Strom langsam genug, um Druckanstieg über 8E-5 Torr zu vermeiden, bis Ag Granulat schmelzen (wie über eine Sicht-Port beobachtet). Nach dem Druck stabilisiert den Strom auf den eingestellten Punkt entsprechend der Ag Abscheidungsrate von 0,1-0,2 Å / s (ab Kalibrierung) eingestellt und öffnen Sie den Auslöser, um die Abscheidung zu starten. </li><li> Überwachen Sie den wachsenden Ag Schichtdicke mittels QCM und schließen Sie den Auslöser, wenn die Dicke von 14 nm erreicht wird. Lassen Sie das Boot W abkühlen für ca. 15 min, entlasten Sie die Probe. Der Film sollte geglüht werden, um Nanopartikel, sobald nach der Abscheidung zu bilden, wie möglich, Ag Oxidation zu vermeiden. </li><li> Eine Zelle mit einer frisch abgeschiedenen Ag-Film wird in einen mit Stickstoff gespülten Ofen vorgewärmt auf 230 ° C von 0,1 bis 0,2, für 50 Minuten geglüht platziert und dann entladen. Beachten Sie die Änderung im Aussehen der Oberfläche durch Nanopartikel. Rasterelektronenmikroskopie Bild von Ag-Nanopartikeln ist shown in Abb. 2. </li><li> Messen EEP der Zelle mit der Nanopartikel-Array. </li></ol> 3. Die Herstellung der Rückreflektor Der hintere Reflektor besteht aus ~ 300 nm dicken MgF 2 (RI 1,38) dielektrische Verkleidung mit einem Mantel von einem kommerziellen weißen Deckenfarbe (Dulux). <ol><li> Vor Herstellung der Rückreflektor die Zell-Kontakte sind durch Aufbringen einer schwarzen Marker-Tinte auf sie zu schützen, die es erlaubt Aussetzen der Kontakte unter dem dielektrischen mit einem Lift-Off-Prozess. </li><li> Verwenden Sie Stickstoff-Pistole, die Probe mit NP-Array und bemalt Kontakte zum Entfernen von Staub zu blasen. Verwenden Sie bescheiden Stickstoffdruck und Bewegung achten, dass die Nanopartikel wegblasen. Legen Sie die Probe in die thermische Verdampfer mit einer W Boot mit MgF 2 Stück gefüllt. Abpumpen des Verdampfers auf Druck von 2 ~ 3E-5 Torr. Stellen Sie QCM Parameter für MgF 2: Dichte 3,05 und Z-Verhältnis 0,637. </li><li> Stellen Sie sicher, dass die Probe Shutter geschlossen ist, auf dem Boot Heizung ein und erhöhen Sie langsam den Strom auf übermäßigen Druckanstieg zu vermeiden, bis MgF 2 schmilzt wie über eine Sicht-Port gesehen. Nachdem der Druck stabilisiert den Strom auf den eingestellten Punkt entsprechend den MgF 2 Abscheiderate von 0,3 nm / s eingestellt und öffnen Sie die Beispieldatenbank Verschlusszeit. </li><li> Überwachen Sie die abgeschiedene Dicke mit QCM und schließen Sie den Auslöser, wenn 300 nm erreicht wird. </li><li> Schalten Sie die Heizung ab. Lassen Sie das Boot W abkühlen lassen für ca. 15 min, entlasten Sie die Probe. Beachten Sie die Änderung in der Zelle mit dem Erscheinungsbild MgF 2 Mantel. </li><li> Um die Farbe Maske aus den Zell-Kontakte entfernen Tauchen Sie die Zelle mit dem dielektrischen Verkleidung in Aceton. Warten Sie, bis das Dielektrikum über der Tinte beginnt Rissbildung und Abheben. Halten der Zelle in Aceton, bis die gesamte Tinte mit der dielektrischen wird entfernt und die Metallkontakte vollständig aufgedeckt. Entfernen Sie die Probe aus Aceton, mit frischem Aceton spülen und trocknen mit Stickstoff Pistole. </li><li> Tragen Sie eine Schicht einweiße Farbe (Dulux One-Coat Deckenfarbe) mit einem feinen Pinsel auf die gesamte Zelloberfläche sorgfältig vermeidet die Metallkontakte. Der Anstrich muss dick genug sein, um völlig undurchsichtig (~&gt; 0,5 mm) sein, so dass kein Licht zu sehen ist, wenn man durch die bemalte Zelle an der hellen Lichtquelle werden. Lassen Sie malen trocken für einen Tag. </li><li> Messen Sie EQE der Zelle mit der weißen Farbe Rückstrahler. </li></ol> 4. Repräsentative Ergebnisse Die Solarzelle Kurzschluss-Strom wird durch Integration der EQE Kurve über den globalen Standard-Sonnenspektrum (Luftmasse 1,5) berechnet. Sowohl der Zelle und ihrer Erweiterung durch lichtabschirmenden auf die Zelle Absorberschicht Dicke ab: der Strom selbst höher ist für dickere Zellen, aber die aktuelle Verstärkung ist höher für schmalere Geräte, siehe Tabelle 1 für die jeweiligen Daten und Animation 5 für EEP Kurven. Die ursprünglichen 2 um dicke Zellen, ohne Licht-Trapping, hAll Jsc bei Schritt 1.7 gemessen.) von ~ 15 mA / cm 2. Nach der Herstellung eines Nanopartikels Array erhöht Jsc bis zu etwa 20 mA / cm 2, was 32% Verbesserung ist. Es ist etwas besser als die verbessernde Wirkung von 25-30% durch die hintere diffusen Reflektor nur. Nach dem Hinzufügen des hinteren diffuser Reflektor auf der MgF 2 Mantel auf die Zelle mit der Plasmonen Nanopartikel Arrays, wird der weitere Jsc auf 22,3 mA / cm 2 erhöht, oder ungefähr 45% Verbesserung. Beachten Sie, dass für die 3 um dicke Zelle alle Ströme höher, bis zu 25,7 mA / cm 2 sind während der relative Verbesserung ist etwas geringer, 42%: Licht-Trapping hat eine relativ größere Wirkung in dünneren Geräten. <table border="1"><tbody><tr><td> Schichtdicke der Zelle: </td><td colspan="2"> 2 um </td><td colspan="2"> 3 um </td></tr><tr><td></td><td> JSC, mA / cm 2 </td><td><s<html> Trong&gt; +% </td><td> JSC, mA / cm 2 </td><td> +% </td></tr><tr><td> Original-Zelle </td><td> 15,4 </td><td></td><td> 18,1 </td><td></td></tr><tr><td> Hintere diffuser Reflektor (R) </td><td> 20,1 </td><td> 30,5 </td><td> 21,5 </td><td> 18,8 </td></tr><tr><td> Nanopartikel (NP) </td><td> 20,3 </td><td> 31,8 </td><td> 21,9 </td><td> 21,0 </td></tr><tr><td> NP / MgF 2 / R </td><td> 22,3 </td><td> 45,3 </td><td> 25,7 </td><td> 42,0 </td></tr></tbody></table> Tabelle 1. Plasmonische Zelle Kurzschluss-Strom und seine Steigerung im Vergleich zur ursprünglichen Zelle. <img alt="1" src="/files/ftp_upload/4092/4092fig1.jpg" /> Abbildung 1. Nahaufnahme von Poly-Si-Dünnschicht-Solarzelle mit Metallisierung Gitter. / Ftp_upload/4092/4092fig2.jpg &quot;/&gt; Abbildung 2. Rasterelektronenmikroskopie Bild von Ag-Nanopartikeln auf dem Silizium-Oberfläche. <img alt="Abbildung 3" src="/files/ftp_upload/4092/4092fig3.jpg" /> Abbildung 3. Eine schematische Darstellung eines plasmonischen kristallinen Silizium-Dünnschicht-Solarzelle (nicht maßstabsgetreu). <img alt="Abbildung 4" src="/files/ftp_upload/4092/4092fig4.jpg" /> Abbildung 4 Externe Quanteneffizienz und Kurzschluss-Strom für die polykristallinen Silizium-Dünnschicht-Zellen mit diffusem Reflektor und plasmonischen Nanopartikel: gestrichelten schwarz - original 2 um dicke Zelle ohne Licht-Trapping, Jsc 15,36 mA / cm 2; blau - Zelle. mit diffuser Lack Reflektor, Jsc 20,08 mA / cm 2; rot - Zelle mit Plasmonen Ag-Nanopartikel, Jsc 20,31 mA / cm 2; grün - Zelle mit Nanopartikeln, MgF 2, Farbe und diffuse Reflektor, Jsc </em&gt; 22,32 mA / cm 2. Lila - 3 um dicke Zelle (auf 3 mm dickem Glas) mit Nanopartikeln, MgF 2, und diffusen Reflektor, Jsc 25,7 mA / cm 2 (beachten Sie, untere blaue Reaktion durch unbeabsichtigte Unterschiede in den AR-Schichten und den Emitter Dicke). Solid black - 2 um dicke texturierte Zelle durch Plasma Enhanced Chemical Vapor Deposition (über 3 mm dickem Glas), JSC 26,4 mA / cm 2, zum Vergleich gezeigt vorbereitet. Animation 1. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation1.pptx" target="_blank">Klicken Sie hier um Animation zu sehen</a> . Animation 2. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation2.pptx" target="_blank">Klicken Sie hier um Animation zu sehen</a> . Animation 3. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation3.pptx" target="_blank">Klicken Sie hier um Animation zu sehen</a>. Animation 4. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation4.pptx" target="_blank">Klicken Sie hier um Animation zu sehen</a> . Animation 5. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation5.pptx" target="_blank">Klicken Sie hier um Animation zu sehen</a> .

<ol>
	<li>Henley, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kerf-free+wafering.">Kerf-free wafering.</a> , 1184-1192 (2010).</li><li>Kunz, O., Wong, J., Janssens, J., Bauer, J., Breitenstein, O., Aberle, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shunting+problems+due+to+sub-micron+pinholes+in+evaporated+solid-phase+crystallised+poly-Si+thin-film+solar+cells+on+glass.">Shunting problems due to sub-micron pinholes in evaporated solid-phase crystallised poly-Si thin-film solar cells on glass.</a> Progress Photovoilt.: Res. Appl. 17, 35-46 (2009).</li><li>Kunz, O., Ouyang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5%+Efficient+evaporated+solid-phase+crystallised+polycrystalline+silicon+solar+cells.">5% Efficient evaporated solid-phase crystallised polycrystalline silicon solar cells.</a> Progress Photovolt.: Res. Appl. 17, 567-573 (2009).</li><li>Van Nieuwenhuysen, K., Payo, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epitaxially+grown+emitters+for+thin+film+silicon+solar+cells+result+in+16%+efficiency.">Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency.</a> Thin Solid Films. 518, S80-S82 (2008).</li><li>Lee, B. G., Stradin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-trapping+by+a+dielectric+nanoparticle+back+reflector+in+film+silicon+solar+cells.">Light-trapping by a dielectric nanoparticle back reflector in film silicon solar cells.</a> Appl. Phys. Lett. 99, 064101 (2011).</li><li>Catchpole, K. R., Polman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+solar+cells.">Plasmonic solar cells.</a> Optics Express. 16, 21793-21800 (2008).</li><li>Ouyang, Z., Zhao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+enhanced+light-trapping+in+thin-film+silicon+solar+cells.">Nanoparticle enhanced light-trapping in thin-film silicon solar cells.</a> Progress Photovolt.: Res. Appl. 19, 917-926 (2011).</li><li>Catchpole, K. R., Polman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+principle+for+particle+plasmon+enhanced+solar+cells.">Design principle for particle plasmon enhanced solar cells.</a> Appl. Phys. Lett. 93, 191113 (2008).</li><li>Beck, F. J., Mokkapati, S., Polman, A., Catchpole, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Asymmetry+in+photocurrent+enhancement+by+plasmonic+nanoparticle+arrays+located+on+the+front+or+on+the+rear+of+solar+cells.">Asymmetry in photocurrent enhancement by plasmonic nanoparticle arrays located on the front or on the rear of solar cells.</a> Appl. Phys. Lett. 96, 033113 (2008).</li><li>Beck, F. J., Verhagen, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resonant+SPP+modes+supported+bt+discrete+metal+nanoparticles+on+high+index+substrates.">Resonant SPP modes supported bt discrete metal nanoparticles on high index substrates.</a> Optics Express. 19, 146-156 (2010).</li><li>Kunz, O., Ouyang, Z., al, a. t. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5%+Efficient+evaporated+solid-phase+crystallised+polycrystalline+silicon+thin-film+solar+cells.">5% Efficient evaporated solid-phase crystallised polycrystalline silicon thin-film solar cells.</a> Progress Photovolt. 17, 567-573 (2009).</li><li>Keevers, M. J., Young, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=10%+Efficient+CSG+minimodules.">10% Efficient CSG minimodules.</a> , 1783-1790 (2007).</li></ol>

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Verdampft polykristallinen Silizium-Solarzellen und die lichtstreuenden plasmonischen Nanopartikel sind ideale Partner für Licht-Trapping. Solche Zellen sind planar und können daher nicht auf lichtstreuenden verlassen aus texturierten Oberflächen, noch kann plasmonischen Nanopartikel leicht auf strukturierten Oberflächen gebildet werden. Die Zellen haben nur einen, hinteren Oberfläche mit Silizium direkt ausgesetzt, der zufällig auch der beste Standort für Nanopartikel effektivste Plasmonen Licht streuenden sein....

<table border="1"><tbody><tr><td> Name des Reagenzes </td><td> Firma </td><td> Katalog-Nummer </td><td> Kommentare </td></tr><tr><td> Silber granulare </td><td> Sigma-Aldrich </td><td> 303372 </td><td> 99,99% </td></tr><tr><td> MgF 2, Random Kristalle, optischer Güte </td><td> Sigma-Aldrich </td><td> 378836 </td><td> &gt; = 99,99% </td></tr><tr><td> Dulux Ein-Schicht-Deckenfarbe </td><td> Dulux </td><td></td><td> R&gt; 90% (500-1100 nm) </td></tr></tbody></table>

polycrystalline silicon thin-film solar cells with plasmonic-enhanced light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Watch this Scientific Journal Video about Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping at JoVE.com

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

Polykristalline Silizium-Dünnschicht-Solarzellen auf Glas werden durch Ablagerung von Bor und Phosphor dotierten Silizium-Schichten durch Kristallisation, Defekt Passivierung und Metallisierung gefolgt hergestellt. Plasmonische Licht-Trapping wird durch Bildung Ag-Nanopartikel auf dem Silizium-Zelloberfläche mit einer diffusen Reflektor was zu ~ 45% Fotostrom Enhancement begrenzt eingeführt.

Polykristalline Silizium-Dünnschicht-Solarzellen mit Plasmonische-enhanced Light-Trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

polycrystalline-silicon-thin-film-solar-cells-with-plasmonic-enhanced

Research

JoVE Journal

Engineering

18.7K Aufrufe.  University of New South Wales. Polykristalline Silizium-Dünnschicht-Solarzellen auf Glas werden durch Ablagerung von Bor und Phosphor dotierten Silizium-Schichten durch Kristallisation, Defekt Passivierung und Metallisierung gefolgt hergestellt. Plasmonische Licht-Trapping wird durch Bildung Ag-Nanopartikel auf dem Silizium-Zelloberfläche mit einer diffusen Reflektor was zu ~ 45% Fotostrom Enhancement begrenzt eingeführt.

Serie: Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

Nanomoulding of Functional Materials, a Versatile Complementary Pattern Replication Method to Nanoimprinting

We describe a nanomoulding technique which allows low-cost nanoscale patterning of functional materials, materials stacks and full devices. Nanomoulding combined with layer transfer enables the replication of arbitrary surface patterns from a master structure onto the functional material. Nanomoulding can be performed on any nanoimprinting setup and can be applied to a wide range of materials and deposition processes. In particular we demonstrate the fabrication of patterned transparent zinc oxide electrodes for light trapping applications in solar cells.

We describe a nanomoulding technique which allows low-cost nanoscale patterning of functional materials, materials stacks and full devices. Nanomoulding can be performed on any nanoimprinting setup and can be applied to a wide range of materials and deposition processes.

Nanomoulding von Functional Materials, ein vielseitiges Complementary Pattern Replication Methode zur Nanoimprinting

We describe a nanomoulding technique which  allows low-cost nanoscale patterning of functional materials, materials stacks  and full devices. Nanomoulding ...

Forschung

Ingenieurwesen

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.
For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.

We offered a method to directly synthesize high c-axis (0002) ZnO thin film by plasma enhanced chemical vapor deposition. The as-synthesized ZnO thin film combined with Pt interdigitated electrode was used as sensing layer for ultraviolet photodetector, showing a high performance through a combination of its good responsivity and reliability.

Synthese und Charakterisierung von Hoch c-Achsen-ZnO-Dünnfilm durch Plasma Enhanced Chemical Vapor Deposition-System und seine UV-Photodetektor Anwendungs

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto ...

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (&#181;c-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated &#181;c-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.

A viable transfer printing-based methodology to introduce plasmonic metal nanostructures in solar cells is described. Using nanopillar poly(dimethylsiloxane) stamps, an Ag-based ordered nanodisk array was integrated with standard hydrogenated microcrystalline Si solar cells, which led to improved device performances due to plasmonic light trapping.

Integration of Light Trapping Silber-Nanostrukturen in Hydrogenated Microcrystalline Silicon Solar Cells durch Transferdruck

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

Iridium-Oxid-reduziertem Graphenoxid Nanohybrid- Thin Film Modified Siebdruck Elektroden als Einweg-Elektro Papier Mikrofluidik pH-Sensoren

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

Digitaldruck von Titandioxid für farbstoffsensibilisierte Solarzellen

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

Rekombinationsdynamik in Dünnschicht-Photovoltaik-Materialien über zeitaufgelöste Mikrowellenleitfähigkeit

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb2+, including Cu+, Na+, and Ag+. A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures.

Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells

Here, we present a protocol to adjust the properties of solution-processed CH3NH3PbI3 through the incorporation of monovalent cation additives in order to achieve highly efficient perovskite solar cells.

Einwertiges Kation Dotierung von CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PbI<sub&gt; 3</sub&gt; Für effiziente Perowskit-Solarzellen

Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical ...

Electrospinning of Photocatalytic Electrodes for Dye-sensitized Solar Cells

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of electrospun titanium dioxide nanofibers (TiO2-NFs) on top of a blocking layer made of commercially available titanium dioxide nanoparticles (TiO2-NPs). This is achieved by first electrospinning a solution of titanium (IV) butoxide, polyvinylpyrrolidone (PVP), and glacial acetic acid in ethanol to obtain composite PVP/TiO2 nanofibers. These are then calcined at 500 &#176;C to remove the PVP and to obtain pure anatase-phase titania nanofibers. This material is characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The photoanode is prepared by first creating a blocking layer through the deposition of a TiO2-NPs/terpineol slurry on a fluorine-doped tin oxide (FTO) glass slide using doctor blading techniques. A subsequent thermal treatment is performed at 500 &#176;C. Then, the light-scattering layer is formed by depositing a TiO2-NFs/terpineol slurry on the same slide, using the same technique, and calcinating again at 500 &#176;C. The performance of the photoanode is tested by fabricating a dye-sensitized solar cell and measuring its efficiency through J-V curves under a range of incident light densities, from 0.25-1 Sun.

The overall goal of this project was to use electrospinning to fabricate a photoanode with improved performance for dye-sensitized solar cells.

Elektrospinnen von photokatalytischen Elektroden für farbstoffsensibilisierte Solarzellen

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

In Situ Überwachung von der beschleunigten Leistungsabfall von Solarzellen und Modulen: eine Fallstudie für Cu (In, Ga) Se2 Solarzellen

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (Cu variant) entropy-stabilized oxides. Phase pure and chemically homogeneous (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (x = 0.20, 0.27, 0.33) and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O (x = 0.11, 0.27) ceramic pellets are synthesized and used in the deposition of ultra-high quality, phase pure, single crystalline thin films of the target stoichiometry. A detailed methodology for the deposition of smooth, chemically homogeneous, entropy-stabilized oxide thin films by pulsed laser deposition on (001)-oriented MgO substrates is described. The phase and crystallinity of bulk and thin film materials are confirmed using X-ray diffraction. Composition and chemical homogeneity are confirmed by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The surface topography of thin films is measured with scanning probe microscopy. The synthesis of high quality, single crystalline, entropy-stabilized oxide thin films enables the study of interface, size, strain, and disorder effects on the properties in this new class of highly disordered oxide materials.

The synthesis of high quality bulk and thin film (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O and (Mg0.25(1-x)Co0.25(1-x)Ni0.25(1-x)CuxZn0.25(1-x))O entropy-stabilized oxides is presented.

Bulk- und Dünnschicht-Synthese von kompositorisch Variante Entropie-stabilisierten Oxide

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...