Este proyecto de investigación es apoyada por el Consejo Australiano de Investigación mediante la concesión vinculación con CSG Solar Pty. Ltd. Jing Rao reconoce su Universidad de NSW Vicerrector de becas posdoctorales. Las imágenes SEM fueron tomadas por Jongsung Parque de utilizar el equipo proporcionado por la Unidad de Microscopía Electrónica de la Universidad de NSW.

1. Fabricación de células solares de silicio policristalino (Animación 3) <ol><li> Silicio deposición de película <ol class="lalpha"><li> Preparar la herramienta evaporación por haz de electrones por hornearlo a cabo a ~ 100 ° C durante la noche para llegar a la presión de base de &lt;3E-8 Torr. Preajuste de la muestra del calentador a la temperatura de 150 ° C en espera. </li><li> Utilizar un sustrato hecho de 5x5 cm 2 (o 10 x 10 cm 2) substrato de vidrio de borosilicato (Schott Borofloat33), 1,1 o 3,3 mm de espesor, revestidas con ~ 80 nm de nitruro de silicio (preparado por PECVD a partir de N 2 y la mezcla de SiH 4). </li><li> Restos de la superficie del sustrato con nitrógeno seco para quitar el polvo, ponerlo en un soporte de la muestra. Ventile el bloqueo de carga, la carga de la muestra, la bomba de la carga, bloquear a la presión &lt;Torr 1E5, y transferir la muestra a la cámara principal. Inicie el calentador para la puesta a punto de 250 ° C. La bomba durante aproximadamente 20 minutos cuando la presión alcanza 8E-8 Torr o inferior. </li><li> Compruebe que el dopantepersianas de origen y la fuente de silicio están cerrados. Prefijados temperaturas fuente dopantes a temperaturas de espera, es decir, la temperatura de la fuente de fósforo a 700 ° C y temperatura de la fuente de boro a 1250 ° C. Empezar electrónico pistola y se funden en un crisol de silicio aumentando lentamente la corriente de e-pistola. </li><li> Cuando la corriente requerida se alcanza (a partir de calibración previa: esta corriente puede variar dependiendo de la dirección de la pistola y las condiciones de origen silicio) se evaporan con capas de silicio dopado con las concentraciones requeridas de P y B: 35 nm en el emisor 1E20 cm -3 de P ; 2 ~ 3 micras, con absorbedor 5E15 -3 cm de B; 100 nm superficie trasera campo (FBS) al 4E19 -3 cm de B. Las concentraciones exactas de dopado se logran haciendo coincidir ciertas velocidades de deposición de Si, medida por cristal de cuarzo monitor (QCM), con ciertas temperaturas de origen dopantes, con relaciones que se establecen a partir de calibración SIMS. </li><li> Después de la evaporación se hace cambiar el calentador, enfríe la muestra durante ~ 10 minutos. Transfer la muestra a la carga de bloqueo, cierre la puerta de válvula, purgar el bloqueo de carga y descarga de la muestra con la película de silicio. </li></ol></li><li> Silicio cristalización Si la muestra es de 10x10 cm 2, se puede cortar en cuatro 5x5 cm 2 piezas de tamaño de células antes de la cristalización. Colocar una película de silicio depositadas sobre vidrio (película de Si arriba) sobre un soporte hecho de rugosa y de nitruro de silicio recubierto de vidrio Schott Robax (para evitar la adherencia). Cargar en un horno purgado con nitrógeno precalentado a 200-300 ° C. Rampa hasta la temperatura hasta 600 ° C a 3 ~ 5 ° C / min y recocido durante 30 horas. Gire a la del calentador de horno y deje enfriar el horno de forma natural a ~ 200 ° C (2 ~ 3 horas) antes de descargar la muestra. La muestra puede tener una forma cóncava debido a la contracción de silicio durante la cristalización. Se aplanan durante el siguiente proceso de cocción rápida. </li><li> Activación del dopante y el defecto de recocido (RTA) Colocar la muestra con la película cristalizó en un soporte de grafito pirolítico y load a un procesador térmico rápido se purgó con argón. Rampa la temperatura hasta 600 ° C a 1 ° C / s, a continuación, hasta 1000 ° C a 20 ° C / s, mantener durante 1 min y después enfriar naturalmente a ~ 100 ° C y descarga. </li><li> Superficie eliminación de óxido Inmediatamente antes de la hidrogenación del óxido de la superficie formada en una película de silicio durante la cristalización y RTA debe ser eliminado para garantizar que la superficie de silicio de película queden expuestos al hidrógeno. Sumergir la muestra recocida en 5% de solución de HF hasta que la superficie de silicio se convierte hidrófobo (30 ~ 100 s). Enjuague con agua desionizada y seque con una pistola de nitrógeno. </li><li> Defecto de pasivación Cargar la muestra en una cámara de vacío equipado con la fuente de plasma de hidrógeno a distancia. De la bomba hasta &lt;1E-4 Torr, calentar la muestra hasta ~ 620 ° C, encender el argón / flujo de la mezcla de hidrógeno (50:150 SCCM), ajustar la presión de 50-100 mTorr, inicie la fuente de plasma de 3,5 kW de la potencia de microondas y continuar el proceso de ~ 10 min. Apague el calentador cuando maintanando el plasma para otro 10-15 minutos hasta que la temperatura cae por debajo de 350 ° C antes de encender el plasma fuera y detener el flujo de gas. Descargue la muestra cuando la temperatura está por debajo de 200 ° C. </li><li> Metalización de la célula Metalización de la célula se lleva a cabo en una serie de patrones consecutivo fotolitográfico, la deposición de película de Al y el grabado pasos que se describen en detalle en 11. El final de células parece se muestra en la última diapositiva de animación en 3. Una vista en primer plano de la celda metalizada se muestra en la figura 1. </li><li> Medir EQE de la célula metalizado. </li></ol> 2. La fabricación de la plasmónica nanopartículas de Ag (Animación 4) <ol><li> Blow la superficie celular metalizado con nitrógeno seco para eliminar el polvo y cargar la muestra en un evaporador de cocción que contienen un barco W llena con gránulos de Ag (0.3-0.5 g). La bomba abajo de la cámara del evaporador a la presión de base de 2 ~ 3E-5 Torr. Programa QCM con parámetros para Ag: Densidad 10,50y Z proporción 0,529. </li><li> Asegúrese de que el obturador de la muestra está cerrada, apague el calentador barco de W y el aumento de la corriente lo suficientemente lento para evitar que suba la presión por encima de 8E-5 Torr hasta que los gránulos Ag fusión (como se observa a través de un punto de vista de un puerto). Después de la presión se estabiliza ajustar la corriente al punto de referencia que corresponde la tasa de deposición de Ag de 0,1-0,2 Å / s (de calibración) y abrir el obturador para iniciar el proceso de deposición. </li><li> Vigilar la creciente espesor Ag película usando QCM y cerrar el obturador cuando el espesor de 14 nm se alcanza. Deje que el barco de W se enfríe durante unos 15 minutos, descargar la muestra. La película debe ser recocido para formar nanopartículas tan pronto como sea posible después de la deposición para evitar la oxidación de Ag. </li><li> Una célula con un recién depositado película de Ag se coloca en un horno purgado con nitrógeno precalentado a 230 ° C 0.1 hasta 0.2, recocido durante 50 minutos, y luego descargado. Tenga en cuenta el cambio en la apariencia de la superficie debido a las nanopartículas. Escaneado de imágenes de microscopía electrónica de las nanopartículas de Ag es shown en la figura. 2. </li><li> Mida EQE de la célula con la matriz de las nanopartículas. </li></ol> 3. La fabricación del reflector trasero El reflector trasero consta de ~ 300 nm de espesor MgF2 (IR 1,38) revestimiento con una capa dieléctrica de una pintura del techo blanco comercial (Dulux). <ol><li> Antes de fabricar la parte trasera del reflector los contactos de células tienen que ser protegidos mediante la aplicación de una tinta marcador negro sobre ellos, que permite la exposición de los contactos de bajo el dieléctrico por un proceso de despegue. </li><li> Use una pistola de nitrógeno para hacer estallar la muestra con la matriz NP y contactos pintadas para quitar el polvo. Use una presión de nitrógeno modesto y tenga cuidado de no soplar las nanopartículas de distancia. Colocar la muestra en el evaporador de cocción que contienen un bote lleno de W MgF2 piezas. La bomba abajo del evaporador a presión de 2 ~ 3E-5 Torr. Establezca los parámetros de QCM para MgF 2: Densidad de 3,05 y la relación de Z 0,637. </li><li> Asegúrese de que la muestra de Shutter está cerrado, encender el calefactor del barco y poco a poco aumentar la intensidad para evitar que suba la presión excesiva hasta que se derrita MgF2 como se ve a través de un puerto de vista. Después de que la presión se estabilice establecer el actual en el punto de consigna correspondiente al MgF2 tasa de deposición de 0.3 nm / s, y abrir el obturador de la muestra. </li><li> Controlar el espesor depositado con QCM y cerrar el obturador cuando se llega a 300 nm. </li><li> Apague el calentador. Deje que el barco de W se enfríe durante unos 15 minutos, descargar la muestra. Nótese el cambio en el aspecto de células con el MgF 2 revestimiento. </li><li> Para retirar la máscara de tinta desde los contactos de células sumerja la celda con el dieléctrico revestimientos en acetona. Espere hasta que el dieléctrico por encima de la tinta comienza a agrietarse y levantándola. Mantener la celda en acetona hasta que toda la tinta con el dieléctrico se retira y los contactos metálicos están expuestos completamente. Retire la muestra a partir de acetona, enjuagar con acetona fresca y secar con una pistola de nitrógeno. </li><li> Aplique una capa de unpintura blanca (Dulux Una Capa de pintura del techo) con un cepillo fino y suave en la superficie de células enteras evitando cuidadosamente los contactos metálicos. La capa de pintura tiene que ser lo suficientemente gruesa como para ser totalmente opaco (~&gt; 0,5 mm), de modo que la luz no puede verse cuando se mira a través del celular pintado en la fuente de luz brillante. Deje secar la pintura por un día. </li><li> Medir EQE de la celda con el reflector posterior pintura blanca. </li></ol> 4. Los resultados representativos La célula solar corriente de cortocircuito se calcula mediante la integración de la curva EQE sobre el estándar espectro solar global (masa de aire 1,5). Tanto la célula actual y su mejora debido a la luz que atrapa dependen del espesor de la celda capa absorbente: la propia corriente es mayor para las más gruesas células, pero la mejora actual es mayor para las más delgadas dispositivos, véase la Tabla 1 para los datos respectivos y Animación 5 para EQE curvas. Los originales de 2 m de espesor células, sin la luz que atrapa, hAve Jsc medido en el paso 1.7.) de ~ 15 mA / cm 2. Después de la fabricación de una matriz de nanopartículas, JSC aumenta hasta aproximadamente 20 mA / cm 2, que es 32% de mejora. Es ligeramente mejor que el efecto de la mejora del 25-30% por el reflector trasero difusa solamente. Después de añadir el reflector trasero difusa en el MgF2 revestimiento a la célula con la matriz de nanopartículas plasmónica, la Comisión Mixta se incrementó a 22,3 mA / cm 2, o aproximadamente el 45% de mejora. Tenga en cuenta que para la celda de 3 m de espesor de todas las corrientes son más altos, hasta 25,7 mA / cm 2, mientras que el aumento relativo es ligeramente inferior, 42%: la luz que atrapa tiene un efecto relativamente grande en dispositivos más delgados. <table border="1"><tbody><tr><td> Grosor: </td><td colspan="2"> 2 micras </td><td colspan="2"> 3 micras </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> célula original </td><td> 15,4 </td><td></td><td> 18,1 </td><td></td></tr><tr><td> Reflector difuso trasero (R) </td><td> 20,1 </td><td> 30,5 </td><td> 21,5 </td><td> 18,8 </td></tr><tr><td> Las nanopartículas (NP) </td><td> 20,3 </td><td> 31,8 </td><td> 21,9 </td><td> 21,0 </td></tr><tr><td> NP / MgF2 / R </td><td> 22,3 </td><td> 45,3 </td><td> 25,7 </td><td> 42,0 </td></tr></tbody></table> Tabla 1. Célula plasmónica corriente de cortocircuito y su mejora en comparación con célula original. <img alt="Figura 1" src="/files/ftp_upload/4092/4092fig1.jpg" /> Figura 1. Vista cercana de poli-silicio de células solares de película delgada con rejilla de metalización. / Ftp_upload/4092/4092fig2.jpg &quot;/&gt; Figura 2. Escaneo de imágenes de microscopía electrónica de las nanopartículas de Ag en la superficie de silicio. <img alt="Figura 3" src="/files/ftp_upload/4092/4092fig3.jpg" /> Figura 3. Una vista esquemática de un plasmónica silicio cristalino de película delgada de células solares (no a escala). <img alt="Figura 4" src="/files/ftp_upload/4092/4092fig4.jpg" /> Figura 4 y la eficiencia cuántica externa de corto circuito de corriente para los de silicio policristalino de película delgada de células con reflector difuso y nanopartículas plasmónica: trazos de color negro - originales 2 m de espesor celda sin luz que atrapa, JSC 15,36 mA / cm 2; azul - celular. con reflector de pintura difusa, JSC 20,08 mA / cm 2; roja - celular con plasmónica nanopartículas de Ag, JSC 20,31 mA / cm 2; verde - celular con nanopartículas, MgF2, la pintura y el reflector difuso, Jsc </em&gt; 22,32 mA / cm 2. Púrpura - 3 m de espesor de células (el 3 de vidrio mm de espesor) con nanopartículas, MgF2, y el reflector difuso, Jsc 25,7 mA / cm 2 (tenga en cuenta la menor respuesta azul debido a las diferencias no intencionales en las capas de AR y el espesor emisor). Sólido negro - 2 m de espesor celular texturizado preparado por el plasma de deposición de vapor químico mejorada (en el vidrio de 3 mm de espesor), JSC 26,4 mA / cm 2, que se muestra para comparación. Animación 1. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation1.pptx" target="_blank">Haga clic aquí para ver la animación</a> . Animación 2. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation2.pptx" target="_blank">Haga clic aquí para ver la animación</a> . Animación 3. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation3.pptx" target="_blank">Haga clic aquí para ver la animación</a>. 4 Animación. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation4.pptx" target="_blank">Haga clic aquí para ver la animación</a> . Animación 5. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation5.pptx" target="_blank">Haga clic aquí para ver la animación</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>

No hay conflictos de interés declarado.

Mezclas en las células de silicio policristalino de solares y las nanopartículas plasmónica dispersión de la luz son los socios ideales para la luz que atrapa. Estas células son planas, por lo que no puede confiar en la luz de dispersión de las superficies con textura, ni las nanopartículas plasmónica formarse fácilmente en las superficies texturadas. Las células tienen sólo uno, con la superficie posterior de silicio expuesto directamente, que también pasa a ser la mejor ubicación para la mayoría de las n...

<table border="1"><tbody><tr><td> Nombre del reactivo </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios </td></tr><tr><td> Granular de Plata </td><td> Sigma-Aldrich </td><td> 303372 </td><td> 99,99% </td></tr><tr><td> MgF 2, los cristales al azar, de grado óptico </td><td> Sigma-Aldrich </td><td> 378836 </td><td> &gt; = 99,99% </td></tr><tr><td> Dulux una capa de pintura del techo </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

Policristalinos de silicio de película delgada de células solares sobre vidrio se fabrican por la deposición de capas de boro y fósforo de silicio dopadas seguido por pasivación defecto de cristalización, y metalización. Plasmónica luz que atrapa se introduce mediante la formación de nanopartículas de Ag en la superficie celular de silicio tapado con un reflector difuso que resulta en la mejora ~ fotocorriente 45%.

De silicio policristalino película delgada de células solares con plasmónica mejorada luz que atrapa

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 vistas.  University of New South Wales. Policristalinos de silicio de película delgada de células solares sobre vidrio se fabrican por la deposición de capas de boro y fósforo de silicio dopadas seguido por pasivación defecto de cristalización, y metalización. Plasmónica luz que atrapa se introduce mediante la formación de nanopartículas de Ag en la superficie celular de silicio tapado con un reflector difuso que resulta en la mejora ~ fotocorriente 45%.

Video: 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 de Functional Materials, un versátil método complementario para la replicación de patrones para nanoimpresión

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

Investigación

Ingeniería

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.

Síntesis y Caracterización de alta eje c ZnO Thin Film por Plasma Enhanced Chemical Vapor Deposition System y su Fotodetector Aplicación UV

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.

Integración de luz de captura de plata de nanoestructuras en células solares de silicio hidrogenado microcristalina por transferencia Impresión

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 grafeno óxido nanohíbrido Thin Film Modificados electrodos serigrafiados reducida de óxido-como Papel desechable de microfluidos electroquímico de pH Sensores

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%.

Impresión digital de dióxido de titanio para células solares sensibilizadas Tinte

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.

La recombinación Dinámica de capa fina en materiales fotovoltaicos a través de conductividad de microondas resuelta en el tiempo

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.

Dopaje de cationes monovalentes de CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PBI<sub&gt; 3</sub&gt; Para células solares eficientes perovskita

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.

Electrospinning de electrodos fotocatalíticos para células solares sensibilizadas por tinte

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 Monitoreo de la degradación de rendimiento acelerado de células solares y módulos: un estudio de caso para celdas solares de Cu (In, Ga) Se2

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.

A granel y síntesis de la película fina de composición variantes óxidos entropía estabilizada

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 ...