Questo progetto di ricerca è sostenuta dal Consiglio di ricerca australiani grazie alla concessione legame con CSG Solar Pty. Ltd. Jing Rao riconosce la sua University of NSW Vice-Cancelliere Postdoctoral Fellowship. Immagini SEM sono state prese da Jongsung Park utilizza l&#39;apparecchiatura fornita dall&#39;Unità Microscopia Elettronica dell&#39;Università degli Studi di NSW.

1. Fabbricazione di celle solari in silicio policristallino (animazione 3) <ol><li> Silicon deposizione di film <ol class="lalpha"><li> Preparare la e-beam strumento evaporazione dalla cottura di fuori a ~ 100 ° C per una notte a raggiungere la pressione di base &lt;3E-8 Torr. Preset il riscaldatore campione alla temperatura di 150 ° C standby. </li><li> Utilizzare un substrato fatto di 5x5 cm 2 (o 10 x10 cm 2) del substrato di vetro borosilicato (Schott Borofloat33), 1,1 o 3,3 mm di spessore, rivestite con ~ 80 nm di nitruro di silicio (preparato PECVD da N 2 e SiH 4 miscela). </li><li> Suonate la superficie del substrato con azoto secco per rimuovere la polvere, metterla in un porta-campioni. Sfiatare il blocco di carico, caricare il campione, pompare il carico bloccare alla pressione &lt;Torr 1E5, e trasferire il campione alla camera principale. Avviare il riscaldatore al set-point di 250 ° C. Pompa per circa 20 minuti quando la pressione raggiunge 8E-8 Torr o inferiore. </li><li> Controllare che il drogantepersiane sorgente di origine e il silicio sono chiuse. Preimpostati sorgenti di temperatura a temperature droganti standby, cioè la temperatura sorgente fosforo a 700 ° C e temperatura boro sorgente a 1250 ° C. Avviare e-gun e si fondono in un crogiolo di silicio aumentando lentamente l&#39;e-gun corrente. </li><li> Quando la corrente desiderata (da calibrazione precedente: questa corrente può variare a seconda delle e-gun e le condizioni della sorgente di Si) evaporare strati di silicio drogato con le concentrazioni richieste di P e B: 35 nm emettitore a 1E20 cm -3 di P ; 2 ~ 3 assorbitore um a 5E15 -3 cm di B; 100 nm back-superficie di campo (BSF) a 4E19 -3 cm di B. Le concentrazioni esatte droganti vengono raggiunti da alcuni corrispondenti velocità di deposizione silicio, come misurato da Quarzo Monitor (QCM), con determinate temperature sorgente drogante, usando le relazioni stabilite dalla calibrazione SIMS. </li><li> Dopo l&#39;evaporazione è fatto spegnere il riscaldatore, raffreddare il campione per ~ 10 min. Transfer il campione al carico-blocco, chiudere il cancello-valvola, sfiatare il blocco di carico e scarico del campione con il film di silicio. </li></ol></li><li> Silicon cristallizzazione Se il campione è 10x10 cm 2, può essere tagliato in quattro pezzi di 5x5 cm 2 cellulari dimensioni prima cristallizzazione. Posizionare un film di silicio depositato su vetro (film Si up) su un supporto fatto di ruvida e rivestito di nitruro di silicio Schott ROBAX vetro (per evitare di attaccare). Carica in un forno preriscaldato a azoto purificato 200-300 ° C. Di salita della temperatura fino a 600 ° C a 3 ~ 5 ° C / min e ricottura per 30 h. Girare del riscaldatore forno e lasciate raffreddare naturalmente forno a ~ 200 ° C (2 ~ 3 ore) prima di scaricare il campione. Il campione può avere una forma concava a causa di restringimento silicio durante la cristallizzazione. Esso appiattire durante il seguente trattamento rapido termico. </li><li> Attivazione del drogante e difetto di ricottura (RTA) Porre il campione con il film cristallizzato su un supporto realizzato di grafite pirolitica e load ad un processore rapido termica lavata con argo. La rampa di temperatura fino a 600 ° C a 1 ° C / s, quindi fino a 1000 ° C a 20 ° C / s, premuto per 1 minuto quindi raffreddare naturalmente a ~ 100 ° C e scarico. </li><li> Superficie di ossido di rimozione Immediatamente prima idrogenazione l&#39;ossido formata sulla superficie del film di silicio durante la cristallizzazione e RTA devono essere rimossi per garantire che la nuda superficie della pellicola di silicio è esposto a idrogeno. Immergere il campione ricotto in soluzione al 5% HF fino a quando la superficie del silicio diventa idrorepellente (30 ~ 100 s). Risciacquare con acqua deionizzata e asciugare con una pistola di azoto. </li><li> Difetto passivazione Caricare il campione in una camera a vuoto dotato di sorgente remota plasma di idrogeno. Pompa al di sotto &lt;1E-4 Torr, riscalda il campione fino a ~ 620 ° C, accendere il argon / miscela flusso di idrogeno (50:150 sccm), impostare la pressione 50-100 mTorr, avviare la sorgente del plasma a 3,5 kW di la potenza delle microonde e continuare il processo per ~ 10 min. Spegnere il riscaldatore, mentre maintaesaminando la plasma per un altro 10-15 min fino a quando la temperatura scende al di sotto 350 ° C prima di girare il plasma spento e arrestare il flusso di gas. Scaricare il campione quando la temperatura è inferiore a 200 ° C. </li><li> Cella metallizzazione Metallizzazione cella viene condotta in una serie consecutiva di patterning fotolitografica, deposizione di film di Al e incisione fasi che sono descritti in dettaglio in 11. La cella finale si presenta come mostrato in l&#39;ultima diapositiva di animazione 3. Una vista ravvicinata della cella metallizzato viene mostrato nella figura 1. </li><li> Misurare EQE della cella metallizzato. </li></ol> 2. Realizzazione della nanoparticelle plasmoniche Ag (Animazione 4) <ol><li> Suonate la superficie metallizzata cella con azoto secco per rimuovere la polvere e caricare il campione in un evaporatore termico, contenenti una barca W riempito con granuli di Ag (0,3-0,5 g). Pump la camera di evaporatore alla pressione di base 2 ~ 3E-5 Torr. QCM di programma con i parametri per Ag: Densità 10,50e Z rapporto di 0,529. </li><li> Assicurarsi che l&#39;otturatore campione è chiuso, accendere il riscaldamento della barca W e aumentare lentamente la corrente sufficiente per evitare l&#39;aumento della pressione al di sopra 8E-5 Torr fino granuli Ag sciogliersi (come osservate attraverso una visione-port). Dopo la pressione si stabilizza impostare la corrente fino al punto corrispondente set la velocità di deposizione Ag di 0,1-0,2 Å / s (da calibrazione) e aprire l&#39;otturatore per avviare il processo di deposizione. </li><li> Monitorare la crescita spessore della pellicola di Ag usando QCM e chiudere l&#39;otturatore quando lo spessore di 14 nm viene raggiunto. Lasciare la barca W raffreddare per circa 15 min, scaricare il campione. Il film deve essere ricotto per formare nanoparticelle appena dopo la deposizione possibile per evitare l&#39;ossidazione Ag. </li><li> Una cella con una pellicola di Ag appena depositato viene posto in un forno preriscaldato spurgato con azoto gassoso a 230 0,1-0,2 ° C, ricotto per 50 min, e quindi scaricato. Notare la variazione di aspetto superficiale a causa di nanoparticelle. Microscopia a scansione elettronica dell&#39;immagine, di nanoparticelle di Ag è shown in Fig. 2. </li><li> Misurare EQE della cellula con la matrice delle nanoparticelle. </li></ol> 3. Realizzazione della riflettore posteriore Il riflettore posteriore è composta da ~ 300 nm di spessore MgF 2 (RI 1.38) rivestimento dielettrico con una mano di vernice commerciale soffitto bianco (Dulux). <ol><li> Prima di fabbricazione del riflettore posteriore i contatti cellule devono essere protetti applicando un inchiostro nero marcatore su di essi, che permette di esporre i contatti da sotto il dielettrico da un lift-off processo. </li><li> Utilizzare la pistola di azoto a soffiare il campione con array di NP e contatti dipinte per rimuovere la polvere. Utilizzare modesta pressione di azoto e fare attenzione a non soffiare via le nanoparticelle. Porre il campione nell&#39;evaporatore termico contenente una barca W riempito con MgF 2 pezzi. Svuotare il evaporatore a pressione di 2 ~ 3E-5 Torr. Impostare i parametri per QCM MgF 2: densità 3,05 e il rapporto Z 0,637. </li><li> Assicurarsi che il campione shutter è chiuso, accendere il riscaldamento barca e aumentare lentamente la corrente per evitare un eccessivo aumento della pressione fino MgF 2 si scioglie come si è visto attraverso una visione-port. Dopo la pressione si stabilizza impostare la corrente al set point che corrispondono a 2 velocità di deposizione MgF di 0,3 nm / s ed aprire l&#39;otturatore campione. </li><li> Monitorare lo spessore depositato utilizzando QCM e chiudere l&#39;otturatore quando 300 nm viene raggiunto. </li><li> Spegnere il riscaldatore. Lasciare la barca W raffreddare per circa 15 minuti, scaricare il campione. Notare il cambiamento nell&#39;aspetto cella con la MgF 2 rivestimento. </li><li> Per rimuovere la maschera di inchiostro dai contatti cella immergere la cella con il rivestimento dielettrico in acetone. Attendere il dielettrico sopra l&#39;inchiostro inizia cracking e sollevando il piede. Mantenere la cella in acetone finché tutto l&#39;inchiostro con il dielettrico viene rimosso e le contatti metallici sono completamente esposti. Rimuovere il campione dal acetone, risciacquare con acetone fresco e secco con la pistola di azoto. </li><li> Applicare uno strato di unavernice bianca (Dulux One-Coat vernice soffitto) con un pennello morbido sulla superficie della cellula intera evitando accuratamente i contatti metallici. Lo strato di vernice deve essere sufficientemente spesso per essere completamente opaca (~&gt; 0,5 mm), così che nessuna luce può essere visto guardando attraverso la cella dipinta alla sorgente luminosa. Lasciate asciugare per dipingere un giorno. </li><li> Misurare EQE della cella con il riflettore posteriore vernice bianca. </li></ol> 4. Risultati rappresentativi La cella solare corrente di corto circuito si calcola integrando la curva EQE rispetto allo standard dello spettro solare globale (massa d&#39;aria 1,5). Sia la cella corrente e la valorizzazione dovuto alla luce-trapping dipendono dallo spessore dello strato assorbente cella: la stessa corrente è maggiore per le cellule ma più spessi il miglioramento corrente è maggiore per i dispositivi più sottili, vedi Tabella 1 per i rispettivi dati e animazione 5 per EQE curve. Le cellule originali 2 micron di spessore, senza luce-trapping, hAve Jsc misurata a passo 1,7.) di ~ 15 mA / cm 2. Dopo la fabbricazione di una matrice di nanoparticelle, Jsc aumenta fino a circa 20 mA / cm 2, che è 32% miglioramento. E &#39;leggermente migliore rispetto all&#39;effetto miglioramento del 25-30% entro il riflettore posteriore diffusa solo. Dopo aver aggiunto il riflettore posteriore diffusa sul MgF 2 rivestimento alla cella con la matrice nanoparticelle plasmoniche, il Jsc è ulteriormente aumentato a 22,3 mA / cm 2, o circa il 45% miglioramento. Si noti che per la cella di 3 micron di spessore tutte le correnti sono più alti, fino a 25,7 mA / cm 2, mentre il miglioramento relativo è leggermente inferiore, 42%: luce-trapping ha un effetto relativamente maggiore in dispositivi più sottili. <table border="1"><tbody><tr><td> Cella spessore: </td><td colspan="2"> 2 um </td><td colspan="2"> 3 pm </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> cella originale </td><td> 15,4 </td><td></td><td> 18,1 </td><td></td></tr><tr><td> Diffusa riflettore posteriore (R) </td><td> 20,1 </td><td> 30,5 </td><td> 21,5 </td><td> 18,8 </td></tr><tr><td> Nanoparticelle (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> Tabella 1. Plasmonici cellula corrente di corto circuito e la sua miglioramento rispetto alla cella originale. <img alt="Figura 1" src="/files/ftp_upload/4092/4092fig1.jpg" /> Figura 1. Close-up vista di poli-Si celle solari a film sottile con griglia metallizzazione. / Ftp_upload/4092/4092fig2.jpg &quot;/&gt; Figura 2. La microscopia elettronica dell&#39;immagine di nanoparticelle Ag sulla superficie del silicio. <img alt="Figura 3" src="/files/ftp_upload/4092/4092fig3.jpg" /> Figura 3. Una vista schematica di un plasmoniche silicio cristallino film sottile cella solare (non in scala). <img alt="Figura 4" src="/files/ftp_upload/4092/4092fig4.jpg" /> Figura 4 esterni efficienza quantica e la corrente di corto circuito per il silicio policristallino celle a film sottile con riflettore diffusa e nanoparticelle plasmoniche: tratteggiata-black - originali 2 micron di spessore cella senza luce-trapping, Jsc 15,36 mA / cm 2; blu - cell. con riflettore vernice diffusa, Jsc 20,08 mA / cm 2; rosso - cellulare con plasmoniche nanoparticelle Ag, Jsc 20,31 mA / cm 2; verde - cellulare con nanoparticelle, MgF 2, e riflettore vernice diffusa, Jsc </em&gt; 22,32 mA / cm 2. Viola - 3 celle micron di spessore (il 3 mm di vetro di spessore) con nanoparticelle, MgF 2, e riflettore diffusa, Jsc 25,7 mA / cm 2 (nota più bassa la risposta blu a causa delle differenze non intenzionali negli strati AR e lo spessore emettitore). Solido bianco - 2 cellula um di spessore testurizzati preparato mediante deposizione di vapore chimico maggiore plasma (il vetro 3 mm di spessore), Jsc 26,4 mA / cm 2, mostrata per comparazione. Animazione 1. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation1.pptx" target="_blank">Clicca qui per vedere Animation</a> . Animation 2. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation2.pptx" target="_blank">Clicca qui per vedere Animation</a> . Animazione 3. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation3.pptx" target="_blank">Clicca qui per vedere Animation</a>. Animazione 4. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation4.pptx" target="_blank">Clicca qui per vedere Animation</a> . Animazione 5. <a href="http://www.jove.com/files/ftp_upload/4092/4092animation5.pptx" target="_blank">Clicca qui per vedere Animation</a> .

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Evaporati celle solari in silicio policristallino e le light-scattering di nanoparticelle plasmoniche sono partner ideali per la luce-trapping. Tali cellule sono planari, quindi non può contare su light-scattering da superfici strutturate, né può essere facilmente nanoparticelle plasmoniche formato su superfici strutturate. Le cellule hanno una sola, superficie posteriore con il silicio esposto direttamente, il che avviene anche per essere la posizione migliore per la maggior parte delle nanoparticelle plasmoniche ef...

<table border="1"><tbody><tr><td> Nome del reattivo </td><td> Azienda </td><td> Numero di catalogo </td><td> Comments </td></tr><tr><td> Granulare Argento </td><td> Sigma-Aldrich </td><td> 303372 </td><td> 99,99% </td></tr><tr><td> MgF 2, cristalli casuali, grado ottico </td><td> Sigma-Aldrich </td><td> 378836 </td><td> &gt; = 99,99% </td></tr><tr><td> Dulux uno-coat soffitto vernice </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

In silicio policristallino a film sottile celle solari su vetro sono fabbricati dalla deposizione di strati di silicio drogati con boro e fosforo, seguita da cristallizzazione, passivazione difetto e metallizzazione. Plasmonici luce trapping viene introdotto formando nanoparticelle Ag sulla superficie cellulare di silicio ricoperto con un riflettore diffuso conseguente miglioramento fotocorrente ~ 45%.

Celle in silicio policristallino solari a film sottile con plasmoniche-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 ...

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Research

JoVE Journal

Engineering

18.7K Views.  University of New South Wales. In silicio policristallino a film sottile celle solari su vetro sono fabbricati dalla deposizione di strati di silicio drogati con boro e fosforo, seguita da cristallizzazione, passivazione difetto e metallizzazione. Plasmonici luce trapping viene introdotto formando nanoparticelle Ag sulla superficie cellulare di silicio ricoperto con un riflettore diffuso conseguente miglioramento fotocorrente ~ 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 di materiali funzionali, un modello versatile complementare replica Metodo di nanoimprinting

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

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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.

Sintesi e caratterizzazione di alta c-asse ZnO film sottile da potenziato a plasma Chemical Vapor Deposition del sistema e la sua applicazione Rilevatori 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.

Integrazione di luce Trapping Argento Nanostrutture in silicio microcristallino idrogenato celle solari tramite bonifico stampa

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.

Grafene ossido nanoibrido film sottile elettrodi serigrafati Iridium ossido-riduzione modificato come usa e getta di carta elettrochimica microfluidici pH Sensori

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%.

La stampa digitale di biossido di titanio per le celle solari dye sensibilizzato

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 ricombinazione Dynamics nel fotovoltaici a film sottile Materiali tramite risolta nel tempo Microonde Conducibilità

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.

Cationi monovalenti doping di CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PBI<sub&gt; 3</sub&gt; Per efficienti celle solari Perovskite

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.

Elettrospinning degli elettrodi fotocatalitici per le celle solari sensibilizzate a 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 Monitoraggio del degrado prestazioni accelerate di celle e moduli solari: un caso di studio per le celle solari di 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.

Massa e sintesi di Film sottile di ossidi compositivamente varianti entropia-stabilizzato

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 ...