Support for this work was provided by DOE STTR grant DE-SC0003664 on Parallel Tandem Organic Solar Cells with Carbon Nanotube Sheet Interlayers and Welch Foundation grant AT-1617. The authors thank J. Bykova for providing CNT forests and A. R. Howard, K. Meilczarek, and J. Velten for technical assistance and useful discussions.

1. Indium Tin Oxide (ITO) Patterning e pulizia NOTA: Utilizzare 15Ω / □ vetro ITO, e l&#39;acquisto o tagliare il vetro ITO in dimensioni adatte per spin coating e fotolitografia. È più efficiente per eseguire i passaggi 1,1-1,7 su un pezzo di vetro più grande possibile, e poi tagliato in piccoli dispositivi. Si noti inoltre che i passaggi 1,1-1,7 richiedono il vetro ITO essere orientato con l&#39;ITO rivolta verso l&#39;alto. Questo può essere controllato facilmente con livello di resistenza di un multimetro. <ol><li> Cappotto Spin 1 ml di S1813 photoresist positivo sul ITO-lato del vetro ITO ad una velocità di 3.000 rpm per 1 min. Utilizzare più resistere per i più grandi pezzi di vetro, assicurarsi che l&#39;intero vetro è rivestito, ed eliminare eventuali bolle prima di iniziare la verniciatura di spin. </li><li> Ricottura resist vetro rivestito, su una piastra calda, a 115 ° C per 1 min. </li><li> Caricare il campione e la fotomaschera sul allineatore contatto. </li><li> Esporre il photoresist rivestito di vetro ITO per un approtempo dei casi. Il tempo di esposizione è di circa 10 secondi, ma variano questa volta sulla base dell&#39;intensità della lampada UV, tipo di photoresist, e spessore. </li><li> Sviluppare i substrati-UV esposti in Developer MF311. Processo automatico di un processore centrifuga produce migliori e più ripetibili risultati, ma lo sviluppo può essere fatto manualmente come seguito. <ol><li> Immergere il substrato-UV esposto per 1 min nello sviluppatore, seguita da risciacquo in acqua deionizzata (DI) e asciugatura con una pistola azoto. Perché lo sviluppatore perde forza in fretta, sostituire lo sviluppatore tra i campioni, o in alternativa aumentare il tempo di sviluppo in cui il riutilizzo di sviluppo. </li></ol></li><li> Etch i substrati ITO in acido cloridrico concentrato (HCl). Questo richiede tra 5-10 min in funzione della concentrazione di HCl. Sciacquare in acqua deionizzata, asciugare, e verificare la resistività delle parti incise con un multimetro. Se una conducibilità rimane, etch per un tempo più lungo. </li><li> Dopo l&#39;attacco, rimuovere il photoresist con acetone. Si noti che pronta rimozione del photoresist residuo impedisce HCl da over-incisione del ITO fantasia. </li><li> Se necessario, tagliare i incise ITO substrati di vetro in dimensioni del dispositivo. </li><li> Pulire i substrati ITO in un ultrasonicatore bagno in una sequenza di solventi - acqua distillata, acetone, toluene, metanolo, ed infine alcool isopropilico. </li></ol> 2. OPV Fabrication Sub-cell <ol><li> Preparare P3HT: PC 61 soluzione BM. NOTA: Per i risultati più consistenti, preparare le soluzioni in un ambiente di azoto. E &#39;possibile seguire questa procedura in condizioni ambientali. <ol><li> Trova e annotare la massa di due pulita, ~ 4 fiala di vetro ml e il berretto, e segnarli con un pennarello indelebile per distinguerli da un altro. </li><li> In un vano portaoggetti azoto o argon, trasferire circa 10 mg di poli (3-hexylthiophene-2,5-diil) (P3HT) per una fiala e circa 10 mg di fenil-C 61 -butyric acido metil estere (PC 61 BM) all&#39;altro. </li><li> Pesare nuovamente le fiale per trovare la massa del P3HT e PC 61 BM. </li><li> Trasferire i flaconcini con P3HT e PC 61 BM in un vano portaoggetti per il resto del processo di fabbricazione soluzione. </li><li> Aggiungi un ancoretta magnetica in ciascuna provetta e aggiungere abbastanza clorobenzene per ogni per creare 45 mg / ml soluzione. </li><li> Collocare le soluzioni su una piastra calda agitazione magnetica a 55 ° C per circa 2 ore o fino a quando i soluti completa dissoluzione. </li><li> Miscelare volumi uguali della P3HT e PC 61 BM soluzioni insieme, e lasciare che il mescolare soluzione mista per un&#39;altra ora prima dell&#39;uso. </li></ol></li><li> Preparare PTB7: PC 71 soluzione BM. <ol><li> Ripetere i punti da 2.1.1 a 2.1.4 con poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) e fenil-7,1-butirrico estere metilico (PC 71 BM) invece di P3HT e PC61 BM. </li><li> Fare una miscela del 3% in volume 1,8-diiodooctane (DIO) in clorobenzene. Questo mix si chiama DIO-CB. </li><li> Aggiungere una ancoretta magnetica in ciascuna provetta e aggiungere abbastanza DIO-CB nella fiala PTB7 avere una soluzione 12 mg / ml e abbastanza DIO-CB al PC 71 BM flaconcino di avere un / ml soluzione 40 mg. </li><li> Lasciate che queste soluzioni muovono su una piastra riscaldante a 70 ° C per due giorni. </li><li> Mescolare le soluzioni in rapporto in peso di PTB7 a PC 71 BM di 1 a 1,5. </li><li> Lasciare agitare soluzione mista per un&#39;altra ora a 70 ° C prima dell&#39;uso. </li></ol></li><li> Poli del filtro (3,4-ethylenedioxythiophene): poli (styrenesulfonate) (PEDOT: PSS) attraverso un filtro dimensioni di nylon 0,45 micron pori. Nota: questa procedura utilizza P VP AI4083. </li><li> Spin Coat strati attivi. <ol><li> Inserite il substrato ITO puliti, ITO rivolta verso l&#39;alto, in un pulitore UV-Ozono per 5 min. </li><li> Spin-coat 120 ml di PEDOT filtrato: PSS sul UV-ozono trattati, fantasia ITO- substrato di vetros a 3.000 rpm per 1 min. Questo dovrebbe produrre uno strato spesso 30 nm. </li><li> Ricottura il PEDOT: substrati ITO PSS rivestiti per 5 minuti a 180 ° C. </li><li> Spin-coat 70 ml di P3HT misto: PC 61 BM soluzione su PEDOT: PSS rivestito ITO substrati a circa 1000 rpm per 1 min. Variare la velocità come necessario per depositare uno strato attivo di spessore 200 nm. </li><li> Ricottura il P3HT: substrati PC 61 BM rivestito a 170 ° C per 5 min. I risultati possono variare dalla temperatura di ricottura ottimale. </li><li> Spin-coat 70 ml di PTB7 misto: PC 71 BM soluzione su PEDOT: PSS rivestito ITO substrati a circa 700 rpm per 1 min. Variare la velocità come necessario per depositare uno strato attivo di spessore 100 nm. </li><li> Caricare il PTB7: PC 71 BM substrati rivestiti in alto vuoto (&lt;2 x 10 -6 Torr) camera per rimuovere DIO residuo. In genere, lasciare i campioni nella camera di O / N. </li></ol></li></ol> 3. Realizzare il dispositivo Tandem &lt;ol&gt; <li> Elettrodi in laminato CNT. <ol><li> Tagliare i substrati PTB7 e P3HT a metà per creare un dispositivo in tandem. Un modello ITO specializzata non richiederebbe questo passaggio. Il modello ITO dovrebbe avere almeno due parallele ITO Elettrodi estende da un bordo ad un mm dalla altra. </li><li> Innanzitutto preparare il PTB7 e substrati rivestiti P3HT pulendo via polimero e PEDOT dai bordi del vetro, ed esporre la striscia ITO che verrà utilizzato come elettrodo comune come visto nel primo pannello di figura 1. </li><li> Laminato l&#39;elettrodo comune CNT sulla parte superiore degli elettrodi PTB7 e P3HT. Applicare un film SWCNT posizionando il lato CNT della carta da filtro sul dispositivo, premendo leggermente, quindi peeling la carta da filtro di distanza. Ciò è mostrato nel secondo pannello di figura 1. </li><li> Densificare l&#39;elettrodo CNT sulla superficie applicando metossi-nonafluorobutane (C 4 F 9 OCH 3) (HFE) e rivestendo CNT con una piccola amount del liquido e poi lasciare asciugare le superfici. </li><li> Eliminare il polimero e CNT sopra l&#39;ITO e vetro che avrà l&#39;elettrodo di gate, come mostrato nel terzo pannello di figura 1. Rimuovere tutto il polimero dal vetro per evitare perdite cancello con una lama di rasoio. </li><li> Laminato l&#39;elettrodo di gate CNT sulla zona pulita dei substrati PTB7 e P3HT rivestiti. Laminato la MWCNT tirando dal bordo della foresta MWCNT con una lametta e lasciare che il foglio di stare liberamente tra alcuni tubi capillari. Passare il dispositivo attraverso il foglio indipendente di laminare il CNT sul dispositivo. L&#39;elettrodo di gate deve avere 2-3 volte il numero di strati di cui sull&#39;elettrodo comune. </li><li> Densificare l&#39;elettrodo di gate con HFE. </li></ol></li><li> Inserite una piccola goccia (≈10 ml) di liquido ionico, N, N -Diethyl- N -methyl- N - (2-metossietil) tetrafluoroborato ammonio, DEME BF-4, in cima a entrambi i CNT elettrodi di unadei substrati. </li><li> Posizionare con cura il substrato senza liquido ionico sulla parte superiore del substrato con liquido ionico con gli elettrodi comuni e porta uno sopra l&#39;altro,. Questo è mostrato in ultimo pannello di figura 1. </li><li> Inserire un fotomaschera con una dimensione di apertura inferiore alla dimensione elettrodo sopra l&#39;area attiva. Utilizzare piccole clip per tenere la fotomaschera in posizione e tenere il dispositivo insieme durante il test. </li></ol> 4. Misurare il dispositivo <ol><li> Trasferire il dispositivo nel vano portaoggetti di misura. </li><li> Effettuare i collegamenti elettrici. <ol><li> Collegare la tensione di gate di alimentazione tra l&#39;elettrodo comune e l&#39;elettrodo di gate con il comune terreno. </li><li> Collegare i due anodi ITO ai fili che sono collegati ad un interruttore che permette la selezione di uno o di entrambi gli anodi anodo. </li><li> Collegare l&#39;uscita del sensore all&#39;ingresso dell&#39;unità di misura di origine. </li><li> Collegare la massa dei meas di origineUnità ure all&#39;elettrodo comune. </li></ol></li><li> Misurare le caratteristiche del dispositivo IV ripetendo le seguenti operazioni per ascendente V Gate. <ol><li> Impostare V Cancello al valore successivo, a partire dal V Porta = 0 V a V gate = 2 V con incrementi di 0,25 V. </li><li> Attendere 5 minuti o fino a quando la corrente di gate è stabilizzata. Idealmente, la corrente di gate dovrebbe stabilizzarsi intorno 10s di nanoampere. </li><li> Impostare l&#39;interruttore di entrambe le sotto-cellule. </li><li> Aprire l&#39;otturatore della lampada. </li><li> Eseguire una scansione di tensione sull&#39;unità misura fonte da volt -1 a +1 volt a circa 100 incrementi o più. </li><li> Eseguire una scansione di tensione da +1 a -1 volt volt. </li><li> Chiudere l&#39;otturatore della lampada. </li><li> Eseguire di nuovo le spazzate di tensione. </li><li> Impostare l&#39;interruttore al sub-cellulare di fronte. </li><li> Ripetere i passaggi da 4.3.4 a 4.3.8. </li><li> Impostare l&#39;interruttore al sub-cellulare di nuovo. </li><li> Ripetere i passaggi da 4.3.4 a 4.3.8. </li></ol></li><li> Calcolare i parametri del dispositivo. &lt;ol&gt; <li> Trova la corrente di corto circuito (J SC) di ogni sub-cellulare a ciascun V gate trovando la corrente prodotta dal dispositivo quando la tensione ai capi del sub-cellula è 0 V. </li><li> Trova la tensione a circuito aperto (V OC) di ogni sub-cellulare a ciascun V gate trovando la tensione prodotta dal dispositivo quando la corrente attraverso il sub-cellula è 0 A. </li><li> Trova la potenza massima della cella solare moltiplicando ogni valore di tensione con ciascun valore di corrente e selezionando il valore massimo (più negativo). Ciò presuppone che si misura Corrente negativo fotografico generati. </li><li> Trova l&#39;efficienza di conversione di potenza (η) dividendo la potenza massima per la potenza della luce di ingresso. </li><li> Trova il fattore di riempimento (FF) dividendo la potenza massima dal prodotto di J SC e V OC. </li></ol></li></ol>

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The authors have nothing to disclose.

I risultati evidenziano alcune considerazioni durante la progettazione di celle solari tandem parallelo. In particolare, se una delle sotto-cellule ha un rendimento scarso, le prestazioni in tandem influenzato negativamente. I risultati mostrano che ci sono due effetti principali. Se un sub-cellulare è in corto, ad esempio, mostra un comportamento ohmico, la FF T non sarà superiore al FF del sub-cellulare male. J T SC e V T OC saranno interessati in modo ...

Semiconduttori polimerici sono i principali fotovoltaico organico (OPV) materiali a causa di elevato assorbimento, buone proprietà di trasporto, flessibilità e compatibilità con i substrati sensibili alla temperatura. Dispositivi OPV efficienza di conversione di potenza, η, hanno saltato in modo significativo negli ultimi anni, con l&#39;efficienza delle celle singole più in alto del 9,1% 1, che li rende una tecnologia energetica sempre più valida. Nonostante i miglioramenti nella η, i sottili spessori ottimali attivi dei dispositivi limitano l&#39;assorbimento della luce e impediscono la fabbricazione affidabile. Inoltre, la larghezza spettrale di assorbimento della luce di ciascun polimero è limitato rispetto ai materiali inorganici. Abbinamento polimeri di diversa sensibilità spettrale scavalca queste difficoltà, rendendo architetture tandem 2 una innovazione necessaria. Dispositivi tandem della serie sono l&#39;architettura più comune tandem. In questo disegno, un materiale di trasporto degli elettronial, uno strato metallico ricombinazione opzionale, e un livello di trasporto buco collegano due strati fotoattivi indipendenti dette sotto-cellule. Collegamento sub-celle in configurazione serie aumenta la tensione a circuito aperto del dispositivo combinato. Alcuni gruppi hanno avuto successo con livelli di trasporto degenerately drogati 3 - 5, ma più gruppi hanno usato le particelle di oro o argento per favorire la ricombinazione di buche ed elettroni l&#39;intercalare 6,7. Al contrario, tandem paralleli richiedono un elettrodo ad alta conducibilità, sia l&#39;anodo o il catodo, che unisce i due strati attivi. Lo strato intermedio deve essere altamente trasparente, che limita interstrati tandem serie contenenti particelle metalliche, e ancor più per le interstrati tandem parallele composte di sottili elettrodi metallici continui. I nanotubi di carbonio (CNT) fogli mostrano maggiore trasparenza di strati metallici. Così l&#39;Istituto NanoTech, in collaborazione con l&#39;Università di Shimane, ha introduced il concetto di utilizzare come elettrodo intercalare nella monolitici, dispositivi tandem parallele 8. I precedenti tentativi presenti monolitici, tandem, dispositivi OPV paralleli con fogli CNT che fungono da anodi intercalare 8,9. Questi metodi richiedono una particolare attenzione per evitare corto circuito di una o entrambe le cellule o strati precedenti dannosi al momento del deposito strati successivi. Il nuovo metodo descritto in questo documento facilita fabbricazione ponendo l&#39;elettrodo CNT sopra i polimerici strati attivi di due singole cellule, poi laminando insieme i due dispositivi separati come mostrato in Figura 1. Questo metodo è notevole come dispositivo, inclusi un&#39;aria -stable CNT catodo, può essere realizzata esclusivamente in condizioni ambientali impiegando solo lavorazione a secco e soluzione. Fogli CNT non sono intrinsecamente buoni catodi, in quanto richiedono drogaggio di tipo n per diminuire la funzione lavoro per raccogliere gli elettroni dalla regione fotoattivodi una cella solare 10. Doppio strato elettrico carica in un elettrolita, come un liquido ionico, può essere utilizzato per spostare la funzione di lavoro del CNT elettrodi 11 - 14. Come descritto in un articolo precedente 15 e illustrato nella Figura 2, quando la tensione di gate (gate V) è aumenta, la funzione lavoro dell&#39;elettrodo comune CNT viene diminuita, creando asimmetria dell&#39;elettrodo. Questo impedisce la raccolta foro dal donatore OPV a favore della raccolta di elettroni da accettore del OPV, ei dispositivi accende, passando da fotoresistenza inefficiente in fotodiodo 15 comportamento. Va inoltre notato che l&#39;energia utilizzata per caricare il dispositivo e il potere perso a causa di correnti di dispersione cancello è banale rispetto alla potenza generata dalla cella solare 15. Gating ionico di elettrodi CNT ha un grande effetto sulla funzione lavoro a causa della bassa densità di stati e l&#39;altosuperficie in rapporto al volume di elettrodi CNT. Metodi simili sono stati utilizzati per migliorare una barriera Schottky all&#39;interfaccia di CNT con n-Si 16.

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			<td height="21" style="height:21px;width:312px;">Name of Material/ Equipment</td>
			<td style="width:191px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate)</td>
			<td style="width:191px;">Heraeus</td>
			<td colspan="2">Clevios PVP AI 4083</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:312px;">poly(3- hexylthiophene-2,5-diyl)&#160;</td>
			<td style="width:191px;">Rieke Metals&#160; Inc.</td>
			<td style="width:119px;">P3HT:&#160; P200</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">phenyl-C61 -butyric&#160; acid methyl&#160; ester</td>
			<td style="width:191px;">1- Material</td>
			<td style="width:119px;">PC61BM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b&#8242;]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl})&#160;</td>
			<td style="width:191px;">1- Material</td>
			<td style="width:119px;">PTB7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">phenyl-C61 -butyric acid methyl&#160; ester</td>
			<td style="width:191px;">Solenne</td>
			<td style="width:119px;">PC71BM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1,8-Diiodooctane</td>
			<td style="width:191px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">250295</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Chlorobenzene</td>
			<td style="width:191px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">284513</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Indium Tin Oxide Coated Glass 15 Ohm/SQ</td>
			<td style="width:191px;">Lumtec</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">S1813</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MF311</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HCl</td>
			<td style="width:191px;">UTD Cleanroom</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Acetone</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">A18-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Toluene</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">T323-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Methanol</td>
			<td style="width:191px;">BDH</td>
			<td style="width:119px;">BDH1135-19L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Isopropanol</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:119px;">A416-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">CEE Spincoater</td>
			<td style="width:191px;">Brewer Scientific</td>
			<td style="width:119px;"></td>
			<td>http://www.utdallas.edu/research/cleanroom/tools/CEESpinCoater.htm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Contact Printer</td>
			<td style="width:191px;">Quintel</td>
			<td style="width:119px;">Q4000-6</td>
			<td>http://www.utdallas.edu/research/cleanroom/QuintelPrinter.htm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">CPK Spin Processor</td>
			<td style="width:191px;"></td>
			<td style="width:119px;"></td>
			<td>http://www.utdallas.edu/research/cleanroom/tools/CPKsolvent.htm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:312px;">Spin Coater</td>
			<td style="width:191px;">Laurell</td>
			<td style="width:119px;">WS-400-6NPP/LITE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Glove Box</td>
			<td style="width:191px;">M-Braun</td>
			<td style="width:119px;">Lab Master 130</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Solar Simulator</td>
			<td style="width:191px;">Thermo Oriel/Newport</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Keithley 2400 SMU</td>
			<td style="width:191px;">Keithley/Techtronix</td>
			<td align="right" style="width:119px;">2400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Keithley 7002 Multiplexer</td>
			<td style="width:191px;">Keithley/Techtronix</td>
			<td align="right" style="width:119px;">7002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Ultrasonic Cleaner</td>
			<td style="width:191px;">Kendal</td>
			<td style="width:119px;">HB-S-49HDT</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Micropipette</td>
			<td style="width:191px;">Eppendorf</td>
			<td style="width:119px;">200uL</td>
			<td></td>
		</tr>
	</tbody>
</table>

ambient method for the production of an ionically gated carbon nanotube common cathode in tandem organic solar cells

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

Un dispositivo in tandem formato da polimeri, in particolare polimeri di significativamente differenti band gap, diversa è di interesse pratico in quanto questi dispositivi possono assorbire la più vasta gamma spettrale della luce. In questa struttura di dispositivo, il sub-cellulare PTB7 è la cella posteriore e P3HT è il sub-cellulare anteriore. Questo ha lo scopo di assorbire la maggior quantità di luce come sub-cellulare P3HT è in gran parte trasparente alla luce lunghezza d&#39;onda assorbita dalla sub-cellula...

Watch this Scientific Journal Video about Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells at JoVE.com

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

Metodo ambiente per la produzione di un ionicamente Gated Nanotubi di carbonio catodo comune in celle solari tandem Organic

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

ambient-method-for-production-an-ionically-gated-carbon-nanotube

Research

JoVE Journal

Engineering

9.3K Views.  The University of Texas at Dallas. A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

Video: Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

Controllo della dimensione, forma e stabilità dei polimeri supramolecolari in acqua

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

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Ingegneria

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

Molding Fabrication, densificazione e Replica di microstrutture 3D Nanotubi di carbonio

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

Ossidazione a secco e vuoto ricottura Trattamenti per accordare le proprietà di bagnabilità di matrici di nanotubi di carbonio

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

Synthesis and Functionalization of Nitrogen-doped Carbon Nanotube Cups with Gold Nanoparticles as Cork Stoppers

Nitrogen-doped carbon nanotubes consist of many cup-shaped graphitic compartments termed as nitrogen-doped carbon nanotube cups (NCNCs). These as-synthesized graphitic nanocups from chemical vapor deposition (CVD) method were stacked in a head-to-tail fashion held only through noncovalent interactions. Individual NCNCs can be isolated out of their stacking structure through a series of chemical and physical separation processes. First, as-synthesized NCNCs were oxidized in a mixture of strong acids to introduce oxygen-containing defects on the graphitic walls. The oxidized NCNCs were then processed using high-intensity probe-tip sonication which effectively separated the stacked NCNCs into individual graphitic nanocups. Owing to their abundant oxygen and nitrogen surface functionalities, the resulted individual NCNCs are highly hydrophilic and can be effectively functionalized with gold nanoparticles (GNPs), which preferentially fit in the opening of the cups as cork stoppers. These graphitic nanocups corked with GNPs may find promising applications as nanoscale containers and drug carriers.

We discussed the synthesis of individual graphitic nanocups using a series of techniques including chemical vapor deposition, acid oxidation and probe-tip sonication. By citrate reduction of HAuCl4, the graphitic nanocups were effectively corked with gold nanoparticles due to the chemically reactive edges of the cups.

Sintesi e funzionalizzazione di azoto drogati Coppe nanotubi di carbonio con nanoparticelle di oro come tappi di sughero

Nitrogen-doped carbon  nanotubes consist of many cup-shaped graphitic compartments termed as  nitrogen-doped carbon nanotube cups (NCNCs).  These ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

Utilizzo dello scattering di incidenza di pascolo risolto neutroni Spin Echo per indagare i materiali organici delle celle solari

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Fabbricazione di bassa temperatura Nanotubi di carbonio interconnessioni verticali Compatibile con la tecnologia Semiconductor

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

La quantificazione delle concentrazioni di idrogeno in superficie e di interfaccia Livelli e materiale sfuso attraverso profili di profondità con l&#39;analisi reazione nucleare

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

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 ...

Morphology Control for Fully Printable Organic&#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting material. However, fullerene derivatives are air-sensitive; therefore, air-stable material is needed as an alternative. In the present study, we propose and describe the properties of Ti-alkoxide as an alternative electron-accepting material to fullerene derivatives to create highly air-stable BHJ solar cells. It is well-known that controlling the morphology in the photoactive layer, which is constructed with fullerene derivatives as the electron acceptor, is important for obtaining a high overall efficiency through the solvent method. The conventional solvent method is useful for high-solubility materials, such as fullerene derivatives. However, for Ti-alkoxides, the conventional solvent method is insufficient, because they only dissolve in specific solvents. Here, we demonstrate a new approach to morphology control that uses the molecular bulkiness of Ti-alkoxides without the conventional solvent method. That is, this method is one approach to obtain highly efficient, air-stable, organic-inorganic bulk-heterojunction solar cells.

Morphology Control for Fully Printable Organic&amp;#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

A method for fully printable, fullerene-free, highly air-stable, bulk-heterojunction solar cells based on Ti alkoxides as the electron acceptor and the electron-donating polymer fabrication is described here. Moreover, a method for controlling the morphology of the photoactive layer through the molecular bulkiness of the Ti-alkoxide units is reported.

Controllo Morfologia per Bulk-eterogiunzione completamente stampabili celle solari organiche-inorganici a base di un Ti-alcossido e semiconduttore Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting ...

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Low pressure scanning electron microscopy in a water vapor ambient is used to machine nanoscale to microscale features in carbon nanotube forests.

Precisione fresatura di Nanotubi di carbonio delle foreste Utilizzando bassa pressione Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning ...