Name: development of efficient oleds from solution deposition
Uploaded: 2022-11-04T12:30:00
Description: Watch this Scientific Journal Video about Development of Efficient OLEDs from Solution Deposition at JoVE.com

Forfatterne vil gerne anerkende "EXCILIGHT"-projektet fra EU's Horizon 2020-forsknings- og innovationsprogram under Marie Sklodowska-Curie-tilskudsaftale nr. 674990. Dette arbejde blev også udviklet inden for rammerne af projektet i3N, UIDB/50025/2020 & UIDP/50025/2020, finansieret af nationale midler gennem FCT/MEC.

FORSIGTIG: Følgende trin involverer brug af forskellige opløsningsmidler og organiske materialer, så der skal udvises passende forsigtighed ved håndtering. Brug røghætten og beskyttelsesudstyr såsom laboratoriebriller, ansigtsmasker, handsker og laboratoriefrakker. Vejning af materialerne skal ske præcist ved hjælp af en højpræcisionsvægtmaskine. For at sikre renhed af substraterne, opløsningsaflejring af tynde film og fordampning anbefales det, at alle procedurer udføres i et kontrolleret miljø eller hand...

Protokollen, der bruges her til at fremstille en effektiv OLED i en simpel enhedsstruktur, er relativt enkel. Den elektriske mobilitet moduleres ikke kun af materialesammensætningen af et enhedslag, men afhænger også kritisk af filmmorfologi. Fremstilling af opløsningerne og et passende valg af opløsningsmiddel og koncentration er vigtige. Ingen materialeaggregering kan forekomme, hvilket indebærer fuldstændig opløselighed på nanometrisk skala. Det er også vigtigt at observere opløsningens viskositet. En høj ...

Stigningen i organisk elektronik, der anvendes i dagligdagen, er blevet en uovertruffen virkelighed. Blandt flere organiske elektroniske applikationer er OLED'er måske de mest attraktive. Deres billedkvalitet, opløsning og farverenhed har gjort OLED'er til et primært valg til skærme. Desuden har muligheden for at opnå stor arealemission i ekstremt tynde, fleksible, lette og nemme farveindstillelige OLED'er anvendelser inden for belysning. Imidlertid har nogle teknologiske problemer i forbindelse med fremstillingsprocessen i store områdeudledere udskudt yderligere anvendelse.
Med den første OLED, der arbejder ved lave påførte spændinger1, er der designet nye paradigmer til solid state-belysning, dog med lav ekstern kvanteeffektivitet (EQE). OLED EQE opnås ved forholdet mellem udsendte fotoner (lys) og injicerede elektriske bærere (elektrisk strøm). Et simpelt teoretisk skøn for den maksimale forventede EQE er lig med ηud x ηint 2. Den interne effektivitet (ηint) kan tilnærmes ved ηint = γ x <img alt="Equation 1" src="/files/ftp_upload/61071/61071eq01.jpg" style="margin: auto;"> x Φ PL, hvor γ svarer til ladningsbalancefaktoren, ΦPL er fotoluminescenskvanteudbyttet (PLQY) og <img alt="Equation 1" src="/files/ftp_upload/61071/61071eq01.jpg" style="margin: auto;"> er effektiviteten af emissiv exciton (elektronhulspar) generation. Endelig er ηud afkoblingseffektiviteten2. Hvis afkobling ikke overvejes, er opmærksomheden fokuseret på tre emner: (1) hvor effektivt materialet er til at skabe excitoner, der radiativt rekombinerer, (2) hvor effektive de emissive lag er, og (3) hvor effektiv enhedsstrukturen er til at fremme et velafbalanceret elektrisk system3.
En rent fluorescerende organisk emitter har kun 25% intern kvanteeffektivitet (IQE). Ifølge spin-reglerne er den strålende overgang fra en triplet til en singlet (T→S) forbudt4. Derfor bidrager 75% af de ophidsede elektriske bærere ikke til emissionen af fotoner5. Dette problem blev først overvundet ved hjælp af overgangsmetaller i organiske emitterfosforescens OLED'er 6,7,8,9,10, hvor IQE angiveligt var tæt på 100%11,12,13,14,15,16 . Dette skyldes spin-orbit-koblingen mellem den organiske forbindelse og det tunge overgangsmetal. Ulempen ved sådanne emittere er deres høje omkostninger og dårlige stabilitet. For nylig har rapporter om den kemiske syntese af en ren organisk forbindelse med lav energiseparation mellem de ophidsede triplet- og singlettilstande (∆EST) af Adachi17,18 givet anledning til en ny ramme. Selv om TADF-processen ikke er ny19, har den vellykkede anvendelse af TADF-processen i OLED'er gjort det muligt at opnå høj effektivitet uden at anvende overgangsmetalkomplekser.
I sådanne metalfrie organiske emittere er der stor sandsynlighed for, at de ophidsede bærere i en triplettilstand befolker til singlet-tilstanden; derfor kan IQE opnå en teoretisk grænse på 100%5,20,21,22. Disse TADF-materialer giver excitoner, der kan rekombinere stråling. Disse emittere kræver imidlertid spredning i en matrixvært for at undgå emissionsdæmpning 3,20,21,23,24 i et værts-gæstekoncept. Derudover afhænger dens effektivitet af, hvordan værten (organisk matrix) tilegnes gæstens (TADF) materiale25. Det er også nødvendigt at idealisere enhedens struktur (dvs. tynde lag, materialer og tykkelse) for at opnå en elektrisk afbalanceret enhed (ligevægt mellem huller og elektroner for at undgå tab)26. At opnå det bedste værts-gæstesystem til en elektrisk afbalanceret enhed er grundlæggende for at øge EQE. I TADF-baserede systemer er dette ikke enkelt på grund af ændringerne i de elektriske bærermobiliteter i EML, der ikke let kan indstilles.
Med TADF-emittere er EQE-værdier større end 20% nemme at opnå26,27,28,29. Enhedsstrukturen består dog typisk af tre til fem organiske lag (hultransport / blokering og elektrontransport / blokeringslag, henholdsvis HTL / HBL og ETL / EBL). Derudover fremstilles den ved hjælp af en termisk fordampningsproces, der er høj i omkostninger, teknologisk kompleks og næsten kun til displayapplikationer. Afhængigt af HOMO -niveauerne (højeste besatte molekylære orbital) og LUMO (laveste ubesatte molekylære orbitale) niveauer, elektrisk mobilitet af bærere og tykkelse kan hvert lag injicere, transportere og blokere elektriske bærere og garantere rekombination i det emissive lag (EML).
Reduktion af enhedens kompleksitet (f.eks. en simpel tolagsstruktur) resulterer normalt i et mærkbart fald i EQE, nogle gange til mindre end 5%. Dette sker på grund af den forskellige elektron- og hulmobilitet i EML, og enheden bliver elektrisk ubalanceret. I stedet for den høje effektivitet af excitonoprettelse bliver effektiviteten af emission i EML således lav. Desuden sker der en mærkbar afrulning med et kraftigt fald i EQE, når lysstyrken øges på grund af den høje koncentration af excitoner ved en høj påført spænding og lange spændte levetider 24,30,31. At overvinde sådanne problemer kræver en stærk evne til at manipulere elektriske egenskaber hos det emissive lag. For en simpel OLED-arkitektur ved hjælp af opløsningsdeponerede metoder kan EML's elektriske egenskaber indstilles af opløsningsforberedelses- og aflejringsparametrene32.
Løsningsaflejringsmetoder til organisk baserede enheder er tidligere blevet anvendt31. OLED-fabrikation sammenlignet med den termiske fordampningsproces er af stor interesse på grund af deres forenklede struktur, lave omkostninger og produktion af store områder. Med stor succes i overgangsmetalkomplekser OLED'er er hovedmålet at øge emitteringsområdet, men holde enhedsstrukturen så enkel som muligt33. Metoder som roll-to-roll (R2R)34,35,36, inkjetudskrivning 37,38,39 og slot-die 40 er med succes blevet anvendt i flerlagsfremstilling af OLED'er, hvilket er en mulig industriel tilgang.
På trods af opløsningsaflejringsmetoder til organiske lag, der tjener som et godt valg til forenkling af enhedsarkitektur, kan ikke alle ønskede materialer let deponeres. Der anvendes to typer materialer: små molekyler og polymerer. I opløsningsaflejringsmetoder har små molekyler nogle ulemper, såsom dårlig tyndfilmsuniformitet, krystallisation og stabilitet. Således anvendes polymerer mest på grund af evnen til at danne ensartede tynde film med lav overfladeruhed og på store, fleksible substrater. Desuden skal materialerne have god opløselighed i det passende opløsningsmiddel (hovedsageligt organiske som chloroform, chlorbenzen, dichlorbenzen osv.), Vand eller alkoholderivater.
Ud over opløselighedsproblemet er det nødvendigt at garantere, at et opløsningsmiddel, der anvendes i et lag, ikke bør fungere som et for det foregående lag. Dette tillader en flerlagsstruktur deponeret af den våde proces; Der er dog begrænsninger41. Den mest typiske enhedsstruktur bruger nogle opløsningsaflejrede lag (dvs. det emissive) og et termisk fordampet lag (ETL). Derudover afhænger tyndfilmhomogenitet og morfologi stærkt af aflejringsmetoderne og parametrene. Elektrisk ladningstransport gennem disse lag styres fuldstændigt af en sådan morfologi. Ikke desto mindre bør der med omtanke etableres en afvejning mellem den ønskede endelige anordning og kompatibiliteten af fremstillingsprocessen. Justering af deponeringsparametrene er en nøgle til succes, på trods af at det er tidskrævende arbejde. For eksempel er spinbelægningen ikke en ligetil teknik. Selvom det virker simpelt, er der flere aspekter af tyndfilmdannelse fra en opløsning oven på et roterende substrat, der kræver opmærksomhed.
Udover filmtykkelsesoptimering, manipulation af spindehastighed og tid (tykkelse er et eksponentielt henfald af begge parametre), skal eksperimentatorens handlinger også justeres for at opnå gode resultater. Korrekte parametre afhænger også af opløsningens viskositet, aflejringsområde og opløsningens befugtningsevne/kontaktvinkel på substratet. Der er ingen unikke sæt parametre. Kun grundlæggende antagelser med specifikke justeringer af opløsningen/substratet giver de ønskede resultater. Desuden kan de elektriske egenskaber, der afhænger af lagets molekylære konformation og morfologi, optimeres til ønskede resultater efter protokollen beskrevet her. Når den er afsluttet, er processen enkel og gennemførlig.
Ikke desto mindre fører reduktion af enhedens struktur kompleksitet til et maksimalt EQE-fald; Selvom der kan opnås et kompromis med hensyn til effektivitet vs. lysstyrke. Da et sådant kompromis tillader praktiske anvendelser, kan overskuddet af en enkel, stor områdekompatibel og billig proces blive en realitet. Denne artikel beskriver disse krav, og hvordan du udvikler en opskrift til at håndtere de nødvendige problemer.
Protokollen fokuserer på en grøn TADF-emitter 2PXZ-OXD [2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazol]42 som gæst i en værtsmatrix sammensat af PVK [poly(N-vinylcarbazol)] og OXD-7 [1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzen], hvilket svarer til EML. Der anvendes et elektrontransportlag (ETL) af TmPyPb [1,3,5-Tri(m-pyridin-3-ylphenyl)benzen]. Både anodens og katodens arbejdsfunktioner er optimeret. Anoden består af ITO (indiumtinoxid) med en højledende polymer PEDOT: PSS [poly (3,4-ethylendioxythiophen)-poly (styrenesulfonat)], og katoden består af et dobbelt lag aluminium og LiF (lithiumfluorid).
Endelig deponeres både PEDOT: PSS og EML (PVK: OXD-7: 2PXZ-OXD) ved spinbelægning, mens TmPyPb, LiF og Al er termisk fordampet. I betragtning af den ledende metallignende karakter af PEDOT: PSS er enheden et typisk "to organisk lag" i den enkleste struktur muligt. I EML er TADF-gæst (10% wt.) spredt i værten (90% wt.) sammensat af PVK0,6 + OXD-70,4.

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			<td height="21" style="height:21px;width:507px;">2PXZ-OXD (2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazole)</td>
			<td style="width:207px;">Lumtec ltd</td>
			<td style="width:119px;">1447998-13-1</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">Aluminum (99.999%)</td>
			<td style="width:207px;">Alfa Aesar</td>
			<td style="width:119px;">7429-90-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">Acetone (99.9%)</td>
			<td style="width:207px;">Sigma Aldrich</td>
			<td style="width:119px;">67-64-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">Hellmanex</td>
			<td style="width:207px;">Ossila</td>
			<td style="width:119px;">7778-53-2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">Isopropyl alcohol</td>
			<td style="width:207px;">Sigma Aldrich</td>
			<td style="width:119px;">67-63-0</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">ITO patterned substrates</td>
			<td style="width:207px;">Ossila</td>
			<td style="width:119px;">65997-17-3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">Lithium Fluoride (99.99%)</td>
			<td style="width:207px;">Sigma Aldrich</td>
			<td style="width:119px;">7789-24-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">OXD-7 (1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene)</td>
			<td style="width:207px;">Ossila</td>
			<td style="width:119px;">138372-67-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PEDOT: PSS (Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate)</td>
			<td style="width:207px;">Ossila</td>
			<td style="width:119px;">155090-83-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">PVK (Polyvinlycarbazole) (average Mn 25,000-50,000)</td>
			<td style="width:207px;">Sigma Aldrich</td>
			<td style="width:119px;">25067-59-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:507px;">TmPyPb (1,3,5-Tri(m-pyridin-3-ylphenyl)benzene)</td>
			<td style="width:207px;">Ossila</td>
			<td style="width:119px;">138372-67-5</td>
			<td></td>
		</tr>
	</tbody>
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development of efficient oleds from solution deposition

Brugen af højeffektive organiske emittere baseret på det termisk aktiverede forsinkede fluorescenskoncept (TADF) er interessant på grund af deres 100% interne kvanteeffektivitet. Præsenteret her er en løsningsaflejringsmetode til fremstilling af effektive organiske lysemitterende dioder (OLED'er) baseret på en TADF-emitter i en simpel enhedsstruktur. Denne hurtige, billige og effektive proces kan bruges til alle OLED-emissive lag, der følger værts-gæstekonceptet. De grundlæggende trin beskrives sammen med nødvendige oplysninger til yderligere reproduktion. Målet er at etablere en generel protokol, der let kan tilpasses til de vigtigste organiske udledere, der i øjeblikket undersøges og udvikles.

Figur 5 viser de vigtigste resultater for den fremstillede enhed. Tændingsspændingen var ekstremt lav (~ 3 V), hvilket er et interessant resultat for en to-organisk lags enhed. Den maksimale lysstyrke var omkring 8.000 cd/m2 uden brug af en integrerende kugle. De maksimale værdier for ηc, ηp og EQE var henholdsvis ca. 16 cd/A, 10 lm/W og 8 %. Selvom resultaterne ikke er de bedste tal for fordele for denne TADF-emitter, var de de bedste, der blev fundet i...

Watch this Scientific Journal Video about Development of Efficient OLEDs from Solution Deposition at JoVE.com

Development of Efficient OLEDs from Solution Deposition

Her præsenteres en protokol til fremstilling af effektive, enkle, opløsningsaflejrede organiske lysemitterende dioder med lav afgang.

Udvikling af effektive OLED'er fra løsningsaflejring

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% ...

Fokus på en effektiv måde, det nye vigtige felt inden for printelektronik, specielt til OS, åbner muligheder for virkelig Processen er optimeret til boltmaskinekonceptet. Enkelheden ved OS-smøring i en god afvejning mellem simpel enhedsarkitektur og nyttige effektivitetsgevinster, der er, og nu, et stort teknologisk problem. Hovedproblemerne ud over det korrekte valg af værtsgrebsmålinger, sammensætning, koncentration, opløsningsmiddel og så videre kan fokuseres i tre aspekter, spinkodning af positionen, opløsningsmiddelforberedelse og den elektriske balance i den elektriske ladning.Smøring, via løsning vedvarende proces, synes at være enkel, fordi den er høj i enhedsfibre af fortjeneste. Nogle kritiske aspekter under fabrikation skal være 35. Begynd med at forberede værtsmatrixen.Tilsæt 15 milligram OXD7 til et lille hætteglas. Tilsæt derefter fem milligram PVK. Tilsæt derefter 10 milligram 2PXZOXDTADF-emitter til et andet lille hætteglas.Tilsæt to milliliter chlorbenzen til hætteglasset med værtsmatrixen og en milliliter til hætteglasset med TADF-materialet. Den endelige koncentration af chlorbenzen i begge hætteglas skal være 10 milligram pr. Milliliter. Rør opløsningerne med små rensede magnetiske rørestænger i mindst tre timer, indtil materialerne er helt opløst.Sørg for, at hætteglassene er sikkert dækket med respektive hætter og tæt forseglet med organisk kemikaliesikker film for at undgå fordampning af opløsningsmidler. Rengør sekventielt præmønstrede indiske tinoxid- eller ITO-substrater i et ultralydbad indeholdende 1% hellmanex-opløsning i vand ved 95 grader Celsius, derefter acetone ved stuetemperatur og derefter til propanol ved stuetemperatur i 15 minutter pr. Bad. Håndter underlagene med pincet, der kun rører dem i hjørnet.Prøv substratet med nitrogenflux for at fjerne eventuelle rester af rengøringsopløsningsmiddel. Udsæt derefter substraterne for UV-ozonbehandling i fem minutter med ITO-filmen opad. PEDOT:PSS filtreres med et 0,45 mikrometer polyvinylidenfluoridfilter, og der fyldes en mikropipette med 100 mikroliter af opløsningen.Placer forsigtigt underlaget på spin-koderbilen, og aktiver vakuumsystemet for at fastgøre det. Drej ITO med forsiden opad, og centrer substratområdet så meget som muligt. Indstil parametrene for spinbelægningen til 3.000 o / min i 30 sekunder.Indstil et indledende trin på to til tre sekunder ved lav rotation. Hold mikropipetten vinkelret på substratet, slip PEDOT:PSS i midten af substratet, og start spinkoderen. Når spin-kodningen er afsluttet, skal du slukke for vakuumet og fjerne substratet med en pincet.Brug den lille vatpind gennemblødt i vand til at fjerne den overskydende aflejrede film omkring katoden og hjørneområderne af substratet, der holder det centrale pixelerede område uberørt. Inkuber substratet i en ovn eller på en kogeplade ved 120 grader Celsius i 15 minutter for at fjerne PEDOT: PSS-opløsningsmidlet, overfør det derefter til et handskerum og lad det køle af ved stuetemperatur. For at forberede opløsningen til det nedsænkende lag kombineres 1,8 ml værtsopløsning og 0,2 ml TADF-opløsning i et rent hætteglas.Opløsningen filtreres med et 0,1 mikrometer PTFE-filter, og lad det derefter omrøre i 15 minutter ved stuetemperatur. Følg den tidligere beskrevne procedure for at deponere den anden opløsning med spinkoderen, der spinder ved 2.000 o / min i 60 sekunder. Brug en vatpind gennemblødt i chlorbenzen for at fjerne overskydende af den anden film.Lad underlaget stå på en kogeplade inde i handskerummet ved 70 grader Celsius i 30 minutter for helt at fjerne overskydende chlorbenzen. Lad det derefter køle af ved stuetemperatur. Underlaget indsættes i prøveholderen med den ønskede fordampningsmaske, og sørg for, at filmene vender nedad.Medtag de nødvendige digler og fyld dem med de relevante materialer. Substratholderen anbringes sammen med prøverne i fordamperens prøveholder. Luk kammeret, og pump det ned, og sørg for at følge producentens anvisninger for det specifikke fordampersystem.Fordamp en 40 nanometer film af TNPYPB, derefter en to nanometer film af lithiumfluorid og endelig en 100 nanometer film af aluminium. Karakteristika for de fremstillede lysdioder er vist her. Tændingsspændingen var ekstremt lav, omkring 3 volt, et interessant resultat for en to-organisk lagenhed.Den maksimale lysstyrke var omkring 8.000 candelas pr. Kvadratmeter uden at bruge en integrerende kugle. De maksimale værdier for strømeffektivitet, energieffektivitet og ekstern kvanteeffektivitet var omkring 16 candelaer pr. ampere, 10 lumen pr. watt og 8% henholdsvis. Den gode afvejning mellem enhedsstruktur enkelhed og pålidelighed effektiv bør hævdes den bedst mulige information uden defekter i alle Særligt vigtigt kan metalkonceptet udvides til forskellige slags parametre, for eksempel organiske og uorganiske materialer.Selvom vi særlige specificiteter, er hovedideen

development-of-efficient-oleds-from-solution-deposition

Research

JoVE Journal

Engineering

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

Fremstilling af Nano-manipuleret ledende gennemsigtige Oxider af Impuls Laser Deposition

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Mechanical Expansion of Steel Tubing as a Solution to Leaky Wellbores

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe (casing), and protects metal components from corrosive fluids. These are essential for uncompromised wellbore integrity. Cements can undergo multiple forms of failure, such as debonding at the cement/rock and cement/metal interfaces, fracturing, and defects within the cement matrix. Failures and defects within the cement will ultimately lead to fluid migration, resulting in inter-zonal fluid migration and premature well abandonment. Currently, there are over 1.8 million operating wells worldwide and over one third of these wells have leak related problems defined as Sustained Casing Pressure (SCP)1. 
The focus of this research was to develop an experimental setup at bench-scale to explore the effect of mechanical manipulation of wellbore casing-cement composite samples as a potential technology for the remediation of gas leaks. 
The experimental methodology utilized in this study enabled formation of an impermeable seal at the pipe/cement interface in a simulated wellbore system. Successful nitrogen gas flow-through measurements demonstrated that an existing microannulus was sealed at laboratory experimental conditions and fluid flow prevented by mechanical manipulation of the metal/cement composite sample. Furthermore, this methodology can be applied not only for the remediation of leaky wellbores, but also in plugging and abandonment procedures as well as wellbore completions technology, and potentially preventing negative impacts of wellbores on subsurface and surface environments.

This article reports on a laboratory scale investigation of an existing field procedure and its adaptation for sealing of leaky wellbores. It consists of mechanical expansion of metal pipe, which results in an improved metal/cement bond, ultimate sealing of hydraulic pathways and prevention of gas leaks caused by the presence of a microannular channel.

Mekanisk Udvidelse af Steel Tubing som en løsning på Utætte brøndboringer

Wellbore cement, a procedural component of wellbore completion operations, primarily provides zonal isolation and mechanical support of the metal pipe ...

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

Tin sulfide (SnS) is a candidate material for Earth-abundant, non-toxic solar cells. Here, we demonstrate the fabrication procedure of the SnS solar cells employing atomic layer deposition, which yields 4.36% certified power conversion efficiency, and thermal evaporation which yields 3.88%.

Gør Record-effektivitet SnS Solceller ved Termisk fordampning og Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

Formation of Thick Dense Yttrium Iron Garnet Films Using Aerosol Deposition

Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% of the bulk. The primary advantage of AD is that the deposition takes place entirely at ambient temperature; thereby enabling film growth in material systems with disparate melting temperatures. This report describes in detail the processing steps for preparing the powder and for performing AD using the custom-built system. Representative characterization results are presented from scanning electron microscopy, profilometry, and ferromagnetic resonance for films grown in this system. As a representative overview of the capabilities of the system, focus is given to a sample produced following the described protocol and system setup. Results indicate that this system can successfully deposit 11 &#181;m thick yttrium iron garnet films that are &#160;&#62; 90% of the bulk density during a single 5 min deposition run. A discussion of methods to afford better control of the aerosol and particle selection for improved thickness and roughness variations in the film is provided.

This report describes the use of a custom-built system to perform aerosol deposition of thick films of yttrium iron garnet onto sapphire substrates at RT. The deposited films are characterized using scanning electron microscopy, profilometry, and ferromagnetic resonance to give a representative overview of the capabilities of the technique.

Dannelse af Tykke Tætte Yttrium Iron Garnet Films Brug Aerosol Deposition

Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% ...

Research and Development of High-performance Explosives

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. For newly developed formulations, the process begins with small-scale mixes, thermal testing, and impact and friction sensitivity. Only then do subsequent larger scale formulations proceed to detonation testing, which will be covered in this paper. Recent advances in characterization techniques have led to unparalleled precision in the characterization of early-time evolution of detonations. The new technique of Photonic Doppler Velocimetry (PDV) for the measurement of detonation pressure will be shared and compared with traditional fiber-optic detonation velocity and plate-dent calculation of detonation pressure. In particular, the role of aluminum in explosive formulations will be discussed. Recent developments led to the development of explosive formulations that result in reaction of aluminum very early in the detonation product expansion. This enhanced reaction leads to changes in the detonation velocity and pressure due to reaction of the aluminum with oxygen in the expanding gas products.

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. This paper will share typical development tests associated with the measurement of detonation velocity and detonation pressure.

Forskning og udvikling af højtydende Sprængstoffer

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

Multifunktionel Hybrid Fe<sub&gt; 2</sub&gt; O<sub&gt; 3</sub&gt; Au Nanopartikler for Effektiv plasmoniske Opvarmning

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

Fremstilling af Fully Løsning Forarbejdede Uorganiske nanocrystal fotovoltaiske Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two chalcogenide compositions are demonstrated: Ge23Sb7S70 and As40S60, which have both been studied extensively for planar mid-infrared (mid-IR) microphotonic devices. In this approach, uniform thickness films are fabricated through the use of computer numerical controlled (CNC) motion. Chalcogenide glass (ChG) is written over the substrate by a single nozzle along a serpentine path. Films were subjected to a series of heat treatments between 100 &#176;C and 200 &#176;C under vacuum to drive off residual solvent and densify the films. Based on transmission Fourier transform infrared (FTIR) spectroscopy and surface roughness measurements, both compositions were found to be suitable for the fabrication of planar devices operating in the mid-IR region. Residual solvent removal was found to be much quicker for the As40S60 film as compared to Ge23Sb7S70. Based on the advantages of electrospray, direct printing of a gradient refractive index (GRIN) mid-IR transparent coating is envisioned, given the difference in refractive index of the two compositions in this study.

Electrospray Deposition of Uniform Thickness Ge23Sb7S70 and As40S60 Chalcogenide Glass Films

A method of uniform thickness solution-derived chalcogenide glass film deposition is demonstrated using computer numerical controlled motion of a single-nozzle electrospray.

Elektrospraymassespek Deposition af ensartet tykkelse Ge<sub&gt; 23</sub&gt; Sb<sub&gt; 7</sub&gt; S<sub&gt; 70</sub&gt; Og As<sub&gt; 40</sub&gt; S<sub&gt; 60</sub&gt; chalcogenid Glas Films

Solution-based electrospray film deposition, which is compatible with continuous, roll-to-roll processing, is applied to chalcogenide glasses. Two ...

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.

Monovalent kation doping af CH<sub&gt; 3</sub&gt; NH<sub&gt; 3</sub&gt; PBI<sub&gt; 3</sub&gt; Til Effektive Perovskite solceller

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

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Fabrikation af ultra-tynde farve film med meget absorberende medier bruger skråt Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...