Ma electrode a graphene owonekera bwino komanso otambasuka

Zipangizo zokhala ndi magawo awiri, monga graphene, zimakopa ma semiconductor odziwika bwino komanso ma electronics osinthika. Komabe, mphamvu yayikulu yolimba ya graphene imapangitsa kuti fracturing iwonongeke pang'onopang'ono, zomwe zimapangitsa kuti zikhale zovuta kugwiritsa ntchito mphamvu zake zapadera zamagetsi mu ma electronics otambasuka. Kuti tithe kugwira ntchito bwino kwambiri ndi ma transparent graphene conductors, tinapanga ma graphene nanoscrolls pakati pa ma stacked graphene layers, otchedwa multilayer graphene/graphene scrolls (MGGs). Pansi pa strain, ma scroll ena adalumikiza ma fragmented domains a graphene kuti asunge percolating network yomwe idathandizira kuti conductivity ikhale yabwino kwambiri pa ma high strain. Ma Trilayer MGGs omwe amathandizidwa ndi elastomers adasunga 65% ya conductance yawo yoyambirira pa 100% strain, yomwe ndi yolunjika ku 100% current flow, pomwe ma trilayer films a graphene opanda nanoscrolls adasunga 25% yokha ya starting conductance yawo. Transistor yotambasuka yokhala ndi mpweya wochuluka wopangidwa pogwiritsa ntchito ma MGG pamene ma electrode anali ndi mphamvu yotumizira yokwana >90% ndipo anasunga 60% ya mphamvu yake yoyambirira pa mphamvu ya 120% (yofanana ndi njira yoyendetsera magetsi). Ma transistor olemera kwambiri komanso owonekera bwino a carbon awa amatha kupangitsa kuti ma optoelectronics otambasuka azitha kutambasuka mosavuta.
Ma electronics owonekera bwino omwe amatambasulidwa ndi gawo lomwe likukula lomwe lili ndi ntchito zofunika kwambiri m'makina apamwamba ophatikizidwa ndi zinthu (1, 2) komanso kuthekera kolumikizana ndi ma optoelectronics owonekera bwino (3, 4) kuti apange ma robotic ndi ma displays ofewa apamwamba. Graphene ili ndi makhalidwe abwino kwambiri a makulidwe a atomiki, kuwonekera bwino kwambiri, komanso kuyendetsa bwino kwambiri, koma kugwiritsidwa ntchito kwake m'magwiritsidwe otseguka kwalepheretsedwa ndi chizolowezi chake chosweka pazigawo zazing'ono. Kugonjetsa zofooka zamakina za graphene kungathandize magwiridwe antchito atsopano m'zida zowonekera bwino zomwe zimatambasulidwa.
Makhalidwe apadera a graphene amawapangitsa kukhala oyenera kwambiri m'badwo wotsatira wa ma electrode owongolera owonekera (5, 6). Poyerekeza ndi kondakitala yowonekera yomwe imagwiritsidwa ntchito kwambiri, indium tin oxide [ITO; 100 ohms/square (sq) pa 90% transparency], monolayer graphene yomwe imakula ndi chemical vapor deposition (CVD) ili ndi kuphatikiza kofanana kwa sheet resistance (125 ohms/sq) ndi transparency (97.4%) (5). Kuphatikiza apo, mafilimu a graphene ali ndi kusinthasintha kwakukulu poyerekeza ndi ITO (7). Mwachitsanzo, pa substrate ya pulasitiki, conductance yake imatha kusungidwa ngakhale pa radius yopindika yaing'ono ngati 0.8 mm (8). Kuti ipititse patsogolo magwiridwe ake amagetsi ngati kondakitala yosinthasintha yowonekera, ntchito zam'mbuyomu zapanga zida za graphene hybrid zokhala ndi ma nanowaya asiliva a one-dimensional (1D) kapena ma nanotubes a carbon (CNTs) (9–11). Komanso, graphene yagwiritsidwa ntchito ngati ma electrode a ma semiconductors osakanikirana a heterostructural (monga 2D bulk Si, 1D nanowires/nanotubes, ndi 0D quantum dots) (12), ma transistors osinthasintha, maselo a dzuwa, ndi ma light-emitting diodes (ma LED) (13–23).
Ngakhale kuti graphene yawonetsa zotsatira zabwino pa zamagetsi osinthasintha, kugwiritsidwa ntchito kwake mu zamagetsi otambasulidwa kwachepetsedwa ndi mphamvu zake zamagetsi (17, 24, 25); graphene ili ndi kuuma kwa 340 N/m ndi modulus ya Young ya 0.5 TPa (26). Netiweki yamphamvu ya kaboni-kaboni sipereka njira zotulutsira mphamvu pa kuuma komwe kwagwiritsidwa ntchito ndipo motero imasweka mosavuta pa kuuma kosakwana 5%. Mwachitsanzo, CVD graphene yomwe imasamutsidwa ku polydimethylsiloxane (PDMS) elastic substrate imatha kusunga conductivity yake pa kuuma kosakwana 6% (8). Mawerengedwe a chiphunzitso akuwonetsa kuti kusweka ndi kuyanjana pakati pa zigawo zosiyanasiyana kuyenera kuchepetsa kwambiri kuuma (26). Mwa kuyika graphene m'zigawo zingapo, akuti graphene iyi ya bi- kapena trilayer imatha kutambasulidwa mpaka kuuma kwa 30%, kuwonetsa kusintha kwa kukana kochepera 13 kuposa kwa monolayer graphene (27). Komabe, kutambasuka kumeneku kudakali kochepa kwambiri poyerekeza ndi ma onductor amakono otambasuka (28, 29).
Ma transistors ndi ofunikira kwambiri pa ntchito zotambasuka chifukwa zimathandiza kuwerenga masensa ndi kusanthula kwa zizindikiro (30, 31). Ma transistors pa PDMS okhala ndi graphene yambiri ngati ma electrode oyambira/kutulutsa ndi zinthu zina zoyendera amatha kusunga ntchito zamagetsi mpaka 5% (32), zomwe zili pansi kwambiri pamtengo wofunikira (~50%) wa masensa owunikira thanzi komanso khungu lamagetsi (33, 34). Posachedwapa, njira ya graphene kirigami yafufuzidwa, ndipo transistor yotsekedwa ndi electrolyte yamadzimadzi imatha kutambasulidwa mpaka 240% (35). Komabe, njira iyi imafuna graphene yopachikidwa, zomwe zimapangitsa kuti ntchito yopangira ikhale yovuta.
Apa, timapeza zida za graphene zotambasuka kwambiri mwa kuphatikiza mipukutu ya graphene (yautali wa ~1 mpaka 20 μm, m'lifupi mwake ~0.1 mpaka 1 μm, ndi kutalika kwa ~10 mpaka 100 nm) pakati pa zigawo za graphene. Tikuganiza kuti mipukutu ya graphene iyi ikhoza kupereka njira zoyendetsera ming'alu m'mapepala a graphene, motero kusunga mphamvu yoyendetsa bwino pansi pa mphamvu. Mipukutu ya graphene sifunikira kapangidwe kapena njira yowonjezera; imapangidwa mwachilengedwe panthawi yosinthira madzi. Pogwiritsa ntchito mipukutu ya G/G (graphene/graphene) (MGGs) ya ma electrode otambasuka a graphene (gwero/kutulutsa ndi chipata) ndi ma semiconducting CNTs, tinatha kuwonetsa ma transistors a carbon omwe amatha kutambasuka kwambiri komanso otambasuka kwambiri, omwe amatha kutambasulidwa mpaka 120% (mofanana ndi komwe magetsi amayendera) ndikusunga 60% ya mphamvu yawo yoyambirira. Iyi ndi transistor yopepuka kwambiri yochokera ku carbon mpaka pano, ndipo imapereka mphamvu yokwanira kuyendetsa LED yopanda organic.
Kuti tithe kugwiritsa ntchito ma electrode a graphene owonekera bwino otambasuka m'dera lalikulu, tinasankha graphene yomera m'dera la Cu. Foil ya Cu inapachikidwa pakati pa chubu cha CVD quartz kuti graphene ikule mbali zonse ziwiri, ndikupanga mapangidwe a G/Cu/G. Kuti graphene isamutse, choyamba tinapanga poly(methyl methacrylate) (PMMA) yopota kuti titeteze mbali imodzi ya graphene, yomwe tinayitcha topside graphene (mosiyana ndi mbali inayo ya graphene), ndipo pambuyo pake, filimu yonse (PMMA/top graphene/Cu/bottom graphene) inanyowetsedwa mu (NH4)2S2O8 solution kuti ichotse Cu foil. Graphene ya pansi yopanda PMMA coating mosakayikira idzakhala ndi ming'alu ndi zolakwika zomwe zimalola etchant kulowa mkati (36, 37). Monga momwe zasonyezedwera mu Chithunzi 1A, pansi pa mphamvu ya pamwamba, madera a graphene otulutsidwa adakulungidwa kukhala mipukutu kenako n'kumangiriridwa pa filimu yotsala ya top-G/PMMA. Mipukutu ya pamwamba ya G/G ikhoza kusamutsidwira ku substrate iliyonse, monga SiO2/Si, galasi, kapena polima yofewa. Kubwereza njira yosamutsirayi kangapo ku substrate yomweyo kumapatsa mapangidwe a MGG.
(A) Chithunzi chojambulidwa cha njira yopangira ma MGG ngati electrode yotambasulidwa. Panthawi yosinthira ma graphene, graphene yakumbuyo pa Cu foil inasweka pamalire ndi zolakwika, inakulungidwa m'mawonekedwe osasinthika, ndikulumikizidwa mwamphamvu pamakanema apamwamba, ndikupanga nanoscrolls. Katuni yachinayi ikuwonetsa kapangidwe ka MGG kolumikizidwa. (B ndi C) Mafotokozedwe a TEM apamwamba a monolayer MGG, akuyang'ana kwambiri graphene ya monolayer (B) ndi dera la scroll (C), motsatana. Chithunzi cha (B) ndi chithunzi chocheperako chomwe chikuwonetsa mawonekedwe onse a monolayer MGGs pa gridi ya TEM. Ma Insets a (C) ndi ma profiles a mphamvu omwe atengedwa m'mabokosi amakona anayi omwe awonetsedwa pachithunzichi, komwe mtunda pakati pa ndege za atomiki ndi 0.34 ndi 0.41 nm. (D) Carbon K-edge EEL spectrum yokhala ndi ma graphite a π* ndi σ* omwe amalembedwa. (E) Chithunzi cha AFM cha monolayer G/G scrolls chokhala ndi profile ya kutalika pamzere wachikasu wokhala ndi madontho. (F mpaka I) Optical microscopy ndi chithunzi cha AFM cha trilayer G yopanda (F ndi H) komanso yokhala ndi mipukutu (G ndi I) pa SiO2/Si substrates ya 300-nm-thick, motsatana. Mipukutu yoyimira ndi makwinya adalembedwa kuti awonetse kusiyana kwawo.
Kuti titsimikizire kuti mipukutuyi ndi ya graphene yopindidwa, tinachita kafukufuku wa high-resolution transmission electron microscopy (TEM) ndi electron energy loss (EEL) spectroscopy pa monolayer top-G/G scroll structures. Chithunzi 1B chikuwonetsa kapangidwe ka hexagonal ka monolayer graphene, ndipo chithunzicho ndi mawonekedwe onse a filimuyo yophimbidwa pa dzenje limodzi la carbon la TEM grid. Monolayer graphene imadutsa grid yambiri, ndipo ma graphene flakes ena pamaso pa mikwingwirima yambiri ya hexagonal amawonekera (Chithunzi 1B). Mwa kuyandikira mu scroll imodzi (Chithunzi 1C), tinaona kuchuluka kwa ma graphene lattice fringes, ndi mtunda wa lattice pakati pa 0.34 ndi 0.41 nm. Miyeso iyi ikusonyeza kuti ma flakes amakulungidwa mwachisawawa ndipo si graphite yangwiro, yomwe ili ndi mtunda wa lattice wa 0.34 nm mu "ABAB" layer stacking. Chithunzi 1D chikuwonetsa carbon K-edge EEL spectrum, komwe nsonga ya 285 eV imachokera ku π* orbital ndipo inayo yozungulira 290 eV imachokera ku kusintha kwa orbital ya σ*. Zitha kuwoneka kuti mgwirizano wa sp2 umalamulira kwambiri kapangidwe kameneka, kutsimikizira kuti mipukutuyo ndi yojambula kwambiri.
Zithunzi za optical microscopy ndi atomic force microscopy (AFM) zimapereka chidziwitso pakufalikira kwa ma graphene nanoscrolls mu MGGs (Chithunzi 1, E mpaka G, ndi fanizo S1 ndi S2). Mipukutuyi imagawidwa mwachisawawa pamwamba, ndipo kuchuluka kwake mkati kumawonjezeka mofanana ndi kuchuluka kwa zigawo zomangidwa. Mipukutu yambiri imapindika m'mafundo ndipo imawonetsa kutalika kosagwirizana pakati pa 10 mpaka 100 nm. Ndi yayitali 1 mpaka 20 μm ndipo m'lifupi ndi 0.1 mpaka 1 μm, kutengera kukula kwa ma graphene flakes awo oyamba. Monga momwe zasonyezedwera mu Chithunzi 1 (H ndi I), mipukutuyi ili ndi kukula kwakukulu kuposa makwinya, zomwe zimapangitsa kuti pakhale mawonekedwe ovuta kwambiri pakati pa zigawo za graphene.
Kuti tiyese mphamvu zamagetsi, tinapanga mafilimu a graphene okhala ndi kapena opanda mapangidwe a scroll ndi layer stacking mu 300-μm-wide ndi 2000-μm-long strips pogwiritsa ntchito photolithography. Kukana kwa ma probe awiri monga ntchito ya strain kunayesedwa pansi pa mikhalidwe yozungulira. Kupezeka kwa ma scroll kunachepetsa resistivity ya monolayer graphene ndi 80% ndi kuchepa kwa 2.2% kokha kwa transmittance (chithunzi S4). Izi zikutsimikizira kuti nanoscrolls, zomwe zili ndi mphamvu yamagetsi yayikulu mpaka 5 × 107 A/cm2 (38, 39), zimapereka chithandizo chabwino kwambiri chamagetsi ku MGGs. Pakati pa mono-, bi-, ndi trilayer plain graphene ndi MGGs zonse, trilayer MGG ili ndi conductance yabwino kwambiri yokhala ndi transparency ya pafupifupi 90%. Poyerekeza ndi magwero ena a graphene omwe adanenedwa m'mabuku, tinayesanso ma resistance a four-probe sheet resistances (chithunzi S5) ndipo tinawalemba ngati ntchito yotumizira pa 550 nm (chithunzi S6) mu Chithunzi 2A. MGG ikuwonetsa conductivity yofanana kapena yapamwamba komanso yowonekera bwino kuposa graphene yopangidwa mwaluso yokhala ndi ma multilayer ndi graphene oxide yochepetsedwa (RGO) (6, 8, 18). Dziwani kuti ma sheet resistance a graphene yopangidwa mwaluso yokhala ndi ma multilayer plain graphene yochokera m'mabuku ndi apamwamba pang'ono kuposa a MGG yathu, mwina chifukwa cha kukula kwawo kosakhazikika komanso njira yosamutsira.
(A) Kukana kwa pepala la probe anayi motsutsana ndi kufalikira kwa 550 nm pamitundu ingapo ya graphene, komwe mabwalo akuda amaimira mono-, bi-, ndi trilayer MGGs; mabwalo ofiira ndi ma triangles abuluu amafanana ndi multilayer plain graphene yomwe imakula pa Cu ndi Ni kuchokera ku maphunziro a Li et al. (6) ndi Kim et al. (8), motsatana, kenako nkusunthidwa ku SiO2/Si kapena quartz; ndipo ma triangles obiriwira ndi ma values ​​​​a RGO pa madigiri osiyana ochepetsa kuchokera ku kafukufuku wa Bonaccorso et al. (18). (B ndi C) Kusintha kwabwinobwino kwa kukana kwa mono-, bi- ndi trilayer MGGs ndi G monga ntchito ya perpendicular (B) ndi parallel (C) strain kupita ku njira ya current flow. (D) Kusintha kwabwinobwino kwa bilayer G (wofiira) ndi MGG (wakuda) pansi pa cyclic strain loading mpaka 50% perpendicular strain. (E) Kusintha kwabwinobwino kwa trilayer G (wofiira) ndi MGG (wakuda) pansi pa cyclic strain loading mpaka 90% parallel strain. (F) Kusintha kwa capacitance kwa mono-, bi- ndi trilayer G ndi bi- ndi trilayer MGGs ngati ntchito ya strain. Chigawo chamkati ndi kapangidwe ka capacitor, komwe polymer substrate ndi SEBS ndipo polymer dielectric layer ndi 2-μm-thick-SEBS.
Kuti tiwone momwe MGG imagwirira ntchito mogwirizana ndi kupsinjika, tinasamutsa graphene kupita ku thermoplastic elastomer styrene-ethylene-butadiene-styrene (SEBS) substrates (~2 cm mulifupi ndi ~5 cm kutalika), ndipo mphamvu yamagetsi inayesedwa pamene substrate inatambasulidwa (onani Zipangizo ndi Njira) zonse ziwiri zolunjika komanso zofanana ndi momwe magetsi amayendera (Chithunzi 2, B ndi C). Khalidwe lamagetsi lodalira kupsinjika linakula ndi kulowetsedwa kwa nanoscrolls ndikuwonjezera kuchuluka kwa zigawo za graphene. Mwachitsanzo, pamene kupsinjika kuli kolunjika ku kayendedwe ka magetsi, pa monolayer graphene, kuwonjezera kwa mipukutu kunawonjezera kupsinjika pakusweka kwa magetsi kuchokera pa 5 mpaka 70%. Kulekerera kwa kupsinjika kwa trilayer graphene kumakulanso kwambiri poyerekeza ndi monolayer graphene. Ndi nanoscrolls, pa 100% perpendicular strain, kukana kwa kapangidwe ka trilayer MGG kunawonjezeka ndi 50% yokha, poyerekeza ndi 300% ya trilayer graphene yopanda mipukutu. Kusintha kwa kukana pansi pa cyclic strain load kunafufuzidwa. Poyerekeza (Chithunzi 2D), kukana kwa filimu ya graphene ya bilayer yokhazikika kunawonjezeka pafupifupi nthawi 7.5 pambuyo pa ma cycles a ~700 pa 50% perpendicular strain ndipo kunapitirira kuwonjezeka ndi kukana mu cycle iliyonse. Kumbali ina, kukana kwa MGG ya bilayer yokhazikika kunawonjezeka pafupifupi nthawi 2.5 pambuyo pa ma cycles a ~700. Pogwiritsa ntchito mpaka 90% strain motsatira njira yofanana, kukana kwa graphene ya trilayer kunawonjezeka ~ nthawi 100 pambuyo pa ma cycles a 1000, pomwe ndi ~ nthawi 8 zokha mu MGG ya trilayer (Chithunzi 2E). Zotsatira za cycling zikuwonetsedwa mu chithunzi S7. Kuwonjezeka kwachangu kwa kukana motsatira njira yofanana ndi chifukwa chakuti malo olumikizirana a ming'alu ndi olunjika ku mbali ya kayendedwe ka magetsi. Kupatuka kwa kukana panthawi yokweza ndi kutulutsa mphamvu kumachitika chifukwa cha kubwezeretsedwa kwa viscoelastic kwa SEBS elastomer substrate. Kulimba kwa MGG strips panthawi yoyendetsa njinga kumachitika chifukwa cha kukhalapo kwa mipukutu ikuluikulu yomwe imatha kulumikiza mbali zosweka za graphene (monga momwe AFM yawonera), zomwe zimathandiza kusunga njira yozungulira. Chochitika ichi chosunga mphamvu yozungulira ndi njira yozungulira chanenedwapo kale za mafilimu osweka achitsulo kapena semiconductor pa elastomer substrates (40, 41).
Kuti tiwone mafilimu opangidwa ndi graphene ngati ma electrode a chipata m'zida zotambasuka, tinaphimba gawo la graphene ndi gawo la SEBS dielectric (2 μm wandiweyani) ndikuyang'anira kusintha kwa mphamvu ya dielectric ngati ntchito ya mphamvu (onani Chithunzi 2F ndi Zowonjezera Zipangizo kuti mudziwe zambiri). Tinaona kuti mphamvu ya ma capacitance okhala ndi ma electrode a monolayer ndi bilayer graphene osavuta imachepa mwachangu chifukwa cha kutayika kwa conductivity ya graphene mkati mwa ndege. Mosiyana ndi zimenezi, mphamvu ya ma capacitance omwe amatetezedwa ndi ma MGG komanso ma graphene a trilayer osavuta yawonetsa kuwonjezeka kwa mphamvu ya capacitance ndi mphamvu, zomwe zikuyembekezeredwa chifukwa cha kuchepa kwa mphamvu ya dielectric ndi mphamvu. Kuwonjezeka kwa mphamvu ya capacitance komwe kumayembekezeredwa kunagwirizana bwino ndi kapangidwe ka MGG (chithunzi S8). Izi zikusonyeza kuti MGG ndi yoyenera ngati electrode ya chipata ya ma transistors otambasuka.
Kuti tifufuze bwino ntchito ya 1D graphene scroll pa kulekerera kwa mphamvu ya magetsi komanso kuwongolera bwino kulekanitsa pakati pa zigawo za graphene, tinagwiritsa ntchito ma CNT opangidwa ndi spray kuti tilowe m'malo mwa ma graphene scroll (onani Zowonjezera). Kuti titsanzire kapangidwe ka MGG, tinayika ma CNT atatu (ndiko kuti, CNT1).
(A mpaka C) Zithunzi za AFM za makulidwe atatu osiyanasiyana a CNTs (CNT1)
Kuti timvetse bwino luso lawo monga ma electrode a zamagetsi otambasuka, tinafufuza mwadongosolo mawonekedwe a MGG ndi G-CNT-G omwe ali ndi vuto. Optical microscopy ndi scanning electron microscopy (SEM) si njira zogwira mtima zofotokozera chifukwa zonse sizili ndi kusiyana kwa mitundu ndipo SEM imakumana ndi zinthu zina panthawi yofufuza ma electron pamene graphene ili pa ma polymer substrates (zithunzi S9 ndi S10). Kuti tiwone pamwamba pa graphene pomwe ili ndi vuto, tinasonkhanitsa muyeso wa AFM pa ma trilayer MGG ndi plain graphene titasamutsira ku ma substrates oonda kwambiri (~0.1 mm thick ) ndi elastic SEBS. Chifukwa cha zolakwika zamkati mwa CVD graphene ndi kuwonongeka kwakunja panthawi yosinthira, ming'alu imapangidwa mosalekeza pa graphene yolumikizidwa, ndipo chifukwa cha kupsinjika kowonjezereka, ming'aluyo inakhala yolimba (Chithunzi 4, A mpaka D). Kutengera kapangidwe ka ma electrode okhala ndi kaboni, ming'aluyo imawonetsa mawonekedwe osiyanasiyana (chithunzi S11) (27). Kuchuluka kwa malo osweka (komwe kumatanthauzidwa ngati malo osweka/dera lowunikidwa) kwa graphene yokhala ndi zigawo zambiri ndi kochepa kuposa kwa monolayer graphene pambuyo pa kusweka, zomwe zimagwirizana ndi kuwonjezeka kwa mphamvu yamagetsi ya MGGs. Kumbali ina, mipukutu nthawi zambiri imawoneka kuti ilumikiza ming'alu, kupereka njira zowonjezera zoyendetsera mu filimu yosweka. Mwachitsanzo, monga momwe zalembedwera pachithunzi cha Chithunzi 4B, mpukutu waukulu unadutsa pamng'alu mu trilayer MGG, koma palibe mpukutu womwe unawonedwa mu graphene yosalala (Chithunzi 4, E mpaka H). Mofananamo, CNTs zinalumikizanso ming'alu mu graphene (chithunzi S11). Kuchuluka kwa malo osweka, kuchuluka kwa malo osweka, ndi kukhwima kwa mafilimu zafotokozedwa mwachidule mu Chithunzi 4K.
(A mpaka H) Zithunzi za AFM zomwe zili mu malo a AFM za mipukutu ya G/G ya trilayer (A mpaka D) ndi kapangidwe ka G ya trilayer (E mpaka H) pa elastomer yopyapyala kwambiri ya SEBS (~0.1 mm wandiweyani) pa 0, 20, 60, ndi 100%. Ming'alu ndi mipukutu yoyimira imayikidwa ndi mivi. Zithunzi zonse za AFM zili m'dera la 15 μm × 15 μm, pogwiritsa ntchito bala yofanana ya mtundu monga momwe yalembedwera. (I) Geometry yoyerekeza ya ma electrode a monolayer graphene okhala ndi mapatani pa SEBS substrate. (J) Mapu oyerekeza a logarithmic strain yayikulu mu monolayer graphene ndi SEBS substrate pa 20% external strain. (K) Kuyerekeza kwa crack area density (red column), scroll area density (yellow column), ndi surface roughness (blue column) ya mitundu yosiyanasiyana ya graphene.
Pamene mafilimu a MGG atambasulidwa, pali njira yowonjezera yofunika kwambiri yoti mipukutuyo ingathe kulumikiza madera osweka a graphene, kusunga netiweki yozungulira. Mipukutu ya graphene ndi yabwino chifukwa imatha kukhala ndi ma micrometer makumi ambiri ndipo motero imatha kulumikiza ming'alu yomwe nthawi zambiri imakhala yofanana ndi mikrometer. Kuphatikiza apo, chifukwa mipukutuyo imakhala ndi zigawo zambiri za graphene, ikuyembekezeka kukhala ndi kukana kochepa. Poyerekeza, ma netiweki a CNT okhuthala (otsika) amafunika kuti apereke mphamvu yofanana yolumikizira, chifukwa ma CNT ndi ang'onoang'ono (nthawi zambiri amakhala ndi ma micrometer ochepa) komanso osayendetsa bwino kuposa mipukutu. Kumbali ina, monga momwe zasonyezedwera pachithunzi S12, pomwe graphene imasweka ikatambasulidwa kuti igwirizane ndi kupsinjika, mipukutuyo simasweka, zomwe zikusonyeza kuti yomalizayi ikhoza kukhala ikutsetsereka pa graphene yomwe ili pansi pake. Chifukwa chomwe sakusweka mwina ndi chifukwa cha kapangidwe kake kozungulira, kopangidwa ndi zigawo zambiri za graphene (kutalika kwa ~1 mpaka 2 0 μm, m'lifupi mwake ~0.1 mpaka 1 μm, ndi kutalika kwa ~10 mpaka 100 nm), komwe kali ndi modulus yogwira ntchito bwino kuposa graphene yokhala ndi gawo limodzi. Monga momwe Green ndi Hersam (42) adanenera, ma network achitsulo a CNT (m'mimba mwake wa chubu cha 1.0 nm) amatha kupeza kukana kwa pepala kotsika <100 ohms/sq ngakhale kuti pali kukana kwakukulu pakati pa CNTs. Poganizira kuti mipukutu yathu ya graphene ili ndi m'lifupi mwa 0.1 mpaka 1 μm ndipo mipukutu ya G/G ili ndi malo akuluakulu olumikizirana kuposa CNTs, kukana kwa kukhudzana ndi malo olumikizirana pakati pa mipukutu ya graphene ndi graphene sikuyenera kukhala zinthu zomwe zimalepheretsa kuti pakhale kusuntha kwakukulu.
Graphene ili ndi modulus yapamwamba kwambiri kuposa gawo la SEBS. Ngakhale kuti makulidwe ogwira ntchito a graphene electrode ndi otsika kwambiri kuposa a gawo la substrate, kuuma kwa graphene kumachulukitsa makulidwe ake kumafanana ndi kwa gawo la substrate (43, 44), zomwe zimapangitsa kuti pakhale zotsatira zolimbitsa thupi pang'ono. Tinayesa kusintha kwa graphene ya 1-nm-thickness pa gawo la SEBS (onani Zowonjezera kuti mudziwe zambiri). Malinga ndi zotsatira za kuyerekezera, pamene 20% ya strain ikugwiritsidwa ntchito ku gawo la SEBS kunja, strain yapakati pa graphene ndi ~6.6% (Chithunzi 4J ndi chithunzi S13D), zomwe zikugwirizana ndi zomwe zawonedwa (onani chithunzi S13). Tinayerekeza strain m'madera a graphene ndi substrate pogwiritsa ntchito microscopy ya optical ndipo tinapeza kuti strain m'dera la substrate ndi yochepera kawiri kuposa strain m'dera la graphene. Izi zikusonyeza kuti strain yomwe imagwiritsidwa ntchito pa ma graphene electrode patterns ikhoza kukhala yocheperako, ndikupanga zilumba zolimba za graphene pamwamba pa SEBS (26, 43, 44).
Chifukwa chake, kuthekera kwa ma electrode a MGG kusunga mphamvu yoyendetsa bwino pansi pa mphamvu yokwera mwina kumathandizidwa ndi njira ziwiri zazikulu: (i) Mipukutu imatha kulumikiza madera osagwirizana kuti isunge njira yoyendetsera yoyendetsa, ndipo (ii) mapepala/elastomer ya graphene yokhala ndi zigawo zambiri imatha kutsetsereka pamwamba pa wina ndi mnzake, zomwe zimapangitsa kuti mphamvu yoyendetsa ma electrode a graphene ichepe. Pa zigawo zingapo za graphene yosunthidwa pa elastomer, zigawozo sizimalumikizana mwamphamvu, zomwe zimatha kutsetsereka poyankha mphamvu (27). Mipukutuyo inawonjezeranso kukhwima kwa zigawo za graphene, zomwe zingathandize kuwonjezera kulekanitsidwa pakati pa zigawo za graphene motero zimathandiza kuti zigawo za graphene zitsetsereke.
Zipangizo zokhala ndi mpweya wa kaboni wonse zimatsatiridwa mwachidwi chifukwa cha mtengo wotsika komanso mphamvu zambiri. Pankhani yathu, ma transistors okhala ndi mpweya wa kaboni wonse adapangidwa pogwiritsa ntchito chipata cha graphene chapansi, cholumikizira cha graphene chapamwamba/cholumikizira, semiconductor ya CNT yosankhidwa, ndi SEBS ngati dielectric (Chithunzi 5A). Monga momwe zasonyezedwera mu Chithunzi 5B, chipangizo chokhala ndi mpweya wa kaboni wonse chokhala ndi CNTs ngati gwero/cholumikizira ndi chipata (chipangizo chapansi) sichiwoneka bwino kuposa chipangizo chokhala ndi ma electrode a graphene (chipangizo chapamwamba). Izi zili choncho chifukwa ma network a CNT amafuna makulidwe akuluakulu ndipo, motero, ma transmittance otsika kuti akwaniritse kukana kwa pepala kofanana ndi kwa graphene (chithunzi S4). Chithunzi 5 (C ndi D) chikuwonetsa ma curve oyimira kusamutsa ndi kutulutsa asanayesedwe kwa transistor yopangidwa ndi ma electrode a MGG a bilayer. Kutalika kwa njira ndi kutalika kwa transistor yosasunthidwa kunali 800 ndi 100 μm, motsatana. Chiŵerengero choyezedwa cha on/off ndi chachikulu kuposa 103 ndi ma currents oyambitsa ndi otsegula pamlingo wa 10−5 ndi 10−8 A, motsatana. Mzere wotuluka umasonyeza njira zabwino zolumikizirana ndi saturation zomwe zimadalira bwino ma gate-voltage, zomwe zikusonyeza kukhudzana koyenera pakati pa CNTs ndi ma graphene electrodes (45). Kukana kwa ma graphene electrodes kunawonedwa kuti ndi kotsika kuposa komwe kumagwiritsidwa ntchito ndi Au film yophwanyika (onani chithunzi S14). Kusuntha kwa saturation ya transistor yotambasulidwa ndi pafupifupi 5.6 cm2/Vs, kofanana ndi kwa ma transistors omwewo a CNT osankhidwa ndi polymer pa ma substrates olimba a Si okhala ndi 300-nm SiO2 ngati gawo la dielectric. Kupita patsogolo kwa kuyenda ndikotheka ndi kuchuluka kwa machubu okonzedwa bwino ndi mitundu ina ya machubu (46).
(A) Ndondomeko ya transistor yotambasuka yochokera ku graphene. SWNTs, ma nanotubes a kaboni okhala ndi khoma limodzi. (B) Chithunzi cha ma transistor otambasuka opangidwa ndi ma electrode a graphene (pamwamba) ndi ma electrode a CNT (pansi). Kusiyana kwa kuwonekera bwino kumawonekera bwino. (C ndi D) Ma curve otumizira ndi kutulutsa a transistor yochokera ku graphene pa SEBS musanatseke. (E ndi F) Ma curve otumizira, pa ndi kutseka mphamvu, pa/kutseka chiŵerengero, ndi kuyenda kwa transistor yochokera ku graphene pa mitundu yosiyanasiyana.
Pamene chipangizo chowonekera, chokhala ndi mpweya wonse chikutambasulidwa motsatira njira yofanana ndi njira yonyamulira magetsi, kuwonongeka kochepa kunawonedwa mpaka 120% ya mphamvu. Pakutambasula, kuyenda kunachepa mosalekeza kuchokera pa 5.6 cm2/Vs pa mphamvu ya 0% kufika pa 2.5 cm2/Vs pa mphamvu ya 120% (Chithunzi 5F). Tinayerekezeranso magwiridwe antchito a transistor ndi kutalika kosiyanasiyana kwa njira (onani tebulo S1). Chofunika kwambiri, pa mphamvu yayikulu ngati 105%, ma transistor onsewa adawonetsabe chiŵerengero chapamwamba cha on/off ( >103) ndi kuyenda ( >3 cm2/Vs). Kuphatikiza apo, tafotokoza mwachidule ntchito yonse yaposachedwa pa ma transistor a mpweya wonse (onani tebulo S2) (47–52). Mwa kukonza bwino kupanga chipangizo pa elastomers ndikugwiritsa ntchito ma MGG ngati ma contacts, ma transistor athu a mpweya wonse amasonyeza magwiridwe antchito abwino pankhani ya kuyenda ndi hysteresis komanso kukhala otambasuka kwambiri.
Monga momwe timagwiritsira ntchito transistor yowonekera bwino komanso yotambasuka, tinaigwiritsa ntchito polamulira kusintha kwa LED (Chithunzi 6A). Monga momwe zasonyezedwera mu Chithunzi 6B, LED yobiriwira imatha kuwoneka bwino kudzera mu chipangizo chotambasuka chomwe chili pamwamba pake. Pamene chikutambasuka kufika pa ~100% (Chithunzi 6, C ndi D), mphamvu ya kuwala kwa LED sikusintha, zomwe zikugwirizana ndi momwe transistor imagwirira ntchito yomwe yafotokozedwa pamwambapa (onani filimu S1). Ili ndi lipoti loyamba la mayunitsi owongolera otambasuka opangidwa pogwiritsa ntchito ma electrode a graphene, zomwe zikuwonetsa kuthekera kwatsopano kwa zamagetsi otambasuka a graphene.
(A) Kuzungulira kwa transistor yoyendetsera LED. GND, pansi. (B) Chithunzi cha transistor yonse ya kaboni yotambasulidwa komanso yowonekera bwino pa 0% yokwezedwa pamwamba pa LED yobiriwira. (C) Transistor yonse ya kaboni yowonekera komanso yowonekera bwino yomwe imagwiritsidwa ntchito kusintha LED ikuyikidwa pamwamba pa LED pa 0% (kumanzere) ndi ~100% yowonekera (kumanja). Mivi yoyera imaloza ngati zizindikiro zachikasu pa chipangizocho kusonyeza kusintha kwa mtunda komwe kukutambasulidwa. (D) Mawonekedwe am'mbali a transistor yotambasulidwa, ndi LED ikukankhidwira mu elastomer.
Pomaliza, tapanga kapangidwe ka graphene kowongolera kowonekera bwino komwe kumasunga mphamvu yowongolera kwambiri pansi pa mitundu yayikulu ngati ma electrode otambasuka, kothandizidwa ndi ma graphene nanoscrolls pakati pa zigawo za graphene zolumikizidwa. Mapangidwe a ma electrode a bi- ndi trilayer MGG awa pa elastomer amatha kusunga 21 ndi 65%, motsatana, ya mphamvu yawo ya 0% yowongolera pa mphamvu yokwera kufika 100%, poyerekeza ndi kutayika kwathunthu kwa mphamvu yowongolera pa mphamvu ya 5% ya ma electrode wamba a graphene monolayer. Njira zowonjezera zowongolera za graphene scrolls komanso kuyanjana kofooka pakati pa zigawo zomwe zasamutsidwa zimathandiza kuti mphamvu yowongolera ikhale yolimba kwambiri pansi pa mphamvu. Tinagwiritsanso ntchito kapangidwe ka graphene aka kuti tipange ma transistors otambasuka a carbon yonse. Pakadali pano, iyi ndi transistor yochokera ku graphene yotambasuka kwambiri yokhala ndi mawonekedwe abwino kwambiri popanda kugwiritsa ntchito buckling. Ngakhale kuti kafukufukuyu adachitika kuti graphene igwire ntchito zamagetsi otambasuka, tikukhulupirira kuti njira iyi ikhoza kuwonjezeredwa kuzinthu zina za 2D kuti igwire ntchito zamagetsi a 2D otambasuka.
Graphene ya CVD ya dera lalikulu idakulitsidwa pa ma foil a Cu opachikidwa (99.999%; Alfa Aesar) pansi pa kupanikizika kosalekeza kwa 0.5 mtorr ndi 50–SCCM (standard cubic centimeter per minute) CH4 ndi 20–SCCM H2 ngati zoyambira pa 1000°C. Mbali zonse ziwiri za foil ya Cu zidaphimbidwa ndi monolayer graphene. Gawo lochepa la PMMA (2000 rpm; A4, Microchem) linaphimbidwa mbali imodzi ya foil ya Cu, ndikupanga kapangidwe ka PMMA/G/Cu foil/G. Pambuyo pake, filimu yonseyo idanyowa mu yankho la 0.1 M ammonium persulfate [(NH4)2S2O8] kwa maola pafupifupi awiri kuti ichotse foil ya Cu. Panthawiyi, graphene yosatetezedwa kumbuyo idayamba kung'amba malire a tirigu kenako nkupindidwa kukhala mipukutu chifukwa cha kupsinjika kwa pamwamba. Mipukutuyo idalumikizidwa pa filimu ya graphene yapamwamba yothandizidwa ndi PMMA, ndikupanga mipukutu ya PMMA/G/G. Mafilimuwa adatsukidwa m'madzi oyeretsedwa kangapo ndipo adayikidwa pa substrate yolunjika, monga SiO2/Si yolimba kapena substrate ya pulasitiki. Filimu yolumikizidwayo ikauma pa substrate, chitsanzocho chinanyowetsedwa motsatizana mu acetone, 1:1 acetone/IPA (isopropyl alcohol), ndi IPA kwa masekondi 30 iliyonse kuti achotse PMMA. Mafilimuwa ankatenthedwa pa 100°C kwa mphindi 15 kapena kusungidwa mu vacuum usiku wonse kuti achotse madzi onse omwe anali atagwidwa asanasamutsirepo gawo lina la G/G scroll. Gawoli linali loletsa kuchotsedwa kwa filimu ya graphene kuchokera pa substrate ndikuwonetsetsa kuti MGGs zonse zaphimbidwa panthawi yotulutsa PMMA carrier layer.
Kapangidwe ka kapangidwe ka MGG kanawonedwa pogwiritsa ntchito maikulosikopu yowala (Leica) ndi maikulosikopu yowunikira ma elekitironi (1 kV; FEI). Maikulosikopu ya mphamvu ya atomiki (Nanoscope III, Digital Instrument) idagwiritsidwa ntchito mu tapping mode kuti ione tsatanetsatane wa mipukutu ya G. Kuwonekera bwino kwa filimu kunayesedwa ndi ultraviolet-visible spectrometer (Agilent Cary 6000i). Pa mayesowo pamene mphamvuyo inali motsatira njira yolunjika ya kayendedwe ka mphamvu, photolithography ndi plasma ya O2 zinagwiritsidwa ntchito kupanga mapangidwe a graphene kukhala mikwingwirima (~300 μm mulifupi ndi ~2000 μm kutalika), ndipo ma electrode a Au (50 nm) adayikidwa kutentha pogwiritsa ntchito masks amthunzi kumapeto onse awiri a mbali yayitali. Kenako mipiringidzo ya graphene inalumikizidwa ndi elastomer ya SEBS (~2 cm mulifupi ndi ~5 cm kutalika), ndi mzere wautali wa mipiringidzoyo wofanana ndi mbali yayifupi ya SEBS kutsatiridwa ndi BOE (buffered oxide etch) (HF:H2O 1:6) etching ndi eutectic gallium indium (EGaIn) ngati zolumikizira zamagetsi. Pa mayeso ogwirizana, kapangidwe ka graphene kopanda mapatani (~5 × 10 mm) kanasamutsidwira ku substrates za SEBS, ndi ma axes ataliatali ogwirizana ndi mbali yayitali ya substrate ya SEBS. Pazochitika zonsezi, G yonse (yopanda mipukutu ya G)/SEBS inatambasulidwa mbali yayitali ya elastomer mu chipangizo chogwiritsira ntchito pamanja, ndipo pamalopo, tinayesa kusintha kwawo kwa kukana pansi pa kupsinjika pa probe station ndi semiconductor analyzer (Keithley 4200-SCS).
Ma transistors a carbon omwe amatha kutambasulidwa komanso kuonekera bwino pa substrate yosalala adapangidwa pogwiritsa ntchito njira zotsatirazi kuti apewe kuwonongeka kwa organic solvent kwa polymer dielectric ndi substrate. Ma MGG structures adasamutsidwira ku SEBS ngati ma gate electrodes. Kuti apeze polymer dielectric wosanjikiza woonda (2 μm wandiweyani), yankho la SEBS toluene (80 mg/ml) linazunguliridwa pa octadecyltrichlorosilane (OTS)–modified SiO2/Si substrate pa 1000 rpm kwa mphindi imodzi. Filimu yoonda ya dielectric imatha kusamutsidwa mosavuta kuchokera pamwamba pa hydrophobic OTS kupita ku substrate ya SEBS yokutidwa ndi graphene yokonzedwa kale. Capacitor ikhoza kupangidwa poika electrode yapamwamba yamadzimadzi-chitsulo (EGaIn; Sigma-Aldrich) kuti adziwe capacitance ngati ntchito ya kupsinjika pogwiritsa ntchito mita ya LCR (inductance, capacitance, resistance) (Agilent). Gawo lina la transistor linali ndi ma polymer-sorted semiconducting CNTs, potsatira njira zomwe zanenedwa kale (53). Ma electrod opangidwa ndi mapatani/drain anapangidwa pa ma substrates olimba a SiO2/Si. Pambuyo pake, magawo awiriwa, dielectric/G/SEBS ndi CNTs/patterned G/SiO2/Si, analumikizidwa pamodzi, ndipo anaviikidwa mu BOE kuti achotse substrate olimba a SiO2/Si. Motero, ma transistors owonekera bwino komanso otambasuka anapangidwa. Kuyesa kwamagetsi komwe kunachitidwa pansi pa kupsinjika kunachitika pa njira yotambasula yamanja monga momwe tafotokozera pamwambapa.
Nkhani yowonjezera ya nkhaniyi ikupezeka pa http://advances.sciencemag.org/cgi/content/full/3/9/e1700159/DC1
chithunzi S1. Zithunzi za maikulosikopu ya optical ya monolayer MGG pa SiO2/Si substrates pa kukula kosiyanasiyana.
chithunzi S4. Kuyerekeza kwa ma resistance a pepala awiri ndi ma transmittance @550 nm a mono-, bi- ndi trilayer plain graphene (mabwalo akuda), MGG (mabwalo ofiira), ndi CNTs (katatu wabuluu).
chithunzi S7. Kusintha kwabwinobwino kwa kukana kwa mono- ndi bilayer MGGs (zakuda) ndi G (zofiira) pansi pa ~1000 cyclic strain yomwe imakweza mpaka 40 ndi 90% parallel strain, motsatana.
chithunzi S10. Chithunzi cha SEM cha trilayer MGG pa SEBS elastomer pambuyo pa kupsinjika, kusonyeza mtanda wautali wozungulira ming'alu ingapo.
chithunzi S12. Chithunzi cha AFM cha trilayer MGG pa elastomer yopyapyala kwambiri ya SEBS pa 20% ya strain, kusonyeza kuti scroll inadutsa pa mng'alu.
tebulo S1. Kuyenda kwa ma transistors a kaboni nanotube okhala ndi mawaya awiri a MGG-single-walled pa utali wosiyana wa njira isanayambe komanso itatha kupsinjika.
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Ndi Nan Liu, Alex Chortos, Ting Lei, Lihua Jin, Taeho Roy Kim, Won-Gyu Bae, Chenxin Zhu, Sihong Wang, Raphael Pfattner, Xiyuan Chen, Robert Sinclair, Zhenan Bao
Ndi Nan Liu, Alex Chortos, Ting Lei, Lihua Jin, Taeho Roy Kim, Won-Gyu Bae, Chenxin Zhu, Sihong Wang, Raphael Pfattner, Xiyuan Chen, Robert Sinclair, Zhenan Bao
© 2021 American Association for the Advancement of Science. Maumwini onse ndi otetezedwa. AAAS ndi mnzake wa HINARI, AGORA, OARE, CHORUS, CLOCKSS, CrossRef ndi COUNTER.Science Advances ISSN 2375-2548.