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Timapereka lipoti lodabwitsa la photovoltaic effect mu YBa2Cu3O6.96 (YBCO) ceramic pakati pa 50 ndi 300 K yopangidwa ndi kuwala kwa blue-laser, komwe kumagwirizana mwachindunji ndi superconductivity ya YBCO ndi YBCO-metallic electrode interface. Pali kusintha kwa polarity kwa voc yotseguka yamagetsi Voc ndi Isc yozungulira yanthawi yayitali pamene YBCO ikusintha kuchoka ku superconducting kupita ku state resistive state. Timasonyeza kuti pali mphamvu yamagetsi kudutsa superconductor-normal metal interface, yomwe imapereka mphamvu yolekanitsa mawiri awiri a ma electron-hole opangidwa ndi zithunzi. Kuthekera kwa mawonekedwewa kumatsogolera kuchokera ku YBCO kupita ku elekitirodi yachitsulo pomwe YBCO ikuchita mopitilira muyeso ndikusintha kupita kwina pomwe YBCO ikhala yosagwirizana. Chiyambi cha zomwe zingatheke zitha kulumikizidwa mosavuta ndi kuyandikira kwa mawonekedwe azitsulo-superconductor pomwe YBCO ikuchita bwino kwambiri ndipo mtengo wake ukuyembekezeka kukhala ~ 10–8 mV pa 50 K ndi mphamvu ya laser ya 502 mW/cm2. Kuphatikizika kwa zinthu zamtundu wa p YBCO pamalo abwinobwino ndi mtundu wa n-Ag-paste kumapanga mphambano ya quasi-pn yomwe imayang'anira mawonekedwe a photovoltaic a zoumba za YBCO pa kutentha kwambiri. Zomwe tapeza zitha kuyambitsa njira zatsopano zogwiritsira ntchito zida zamagetsi zamagetsi ndikuwunikiranso kuyandikira pafupi ndi mawonekedwe azitsulo zamtundu wa superconductor.
Magetsi opangidwa ndi zithunzi m'ma superconductors a kutentha kwambiri akhala akunenedwa kumayambiriro kwa zaka za m'ma 1990 ndipo amafufuzidwa mozama kuyambira pamenepo, komabe chikhalidwe chake ndi makina ake sakhala osakhazikika1,2,3,4,5. Mafilimu opyapyala a YBa2Cu3O7-δ (YBCO)6,7,8, makamaka, amaphunziridwa mozama mu mawonekedwe a photovoltaic (PV) selo chifukwa cha mphamvu yake yosinthika gap9,10,11,12,13. Komabe, kukana kwakukulu kwa gawo lapansi nthawi zonse kumapangitsa kuti chipangizocho chikhale chochepa kwambiri komanso chimabisa mawonekedwe a PV a YBCO8. Apa tikuwonetsa chidwi cha photovoltaic chopangidwa ndi kuwala kwa blue-laser (λ = 450 nm) mu YBa2Cu3O6.96 (YBCO) ceramic pakati pa 50 ndi 300 K (Tc ~ 90 K). Timasonyeza kuti zotsatira za PV zimagwirizana mwachindunji ndi superconductivity ya YBCO ndi chikhalidwe cha YBCO-metallic electrode interface. Pali kusintha kwa polarity kwa voc yotseguka yamagetsi Voc ndi Isc yozungulira yanthawi yayitali pamene YBCO idutsa kusintha kuchokera ku gawo la superconducting kupita kumalo otsutsa. Akuti pali mphamvu yamagetsi kudutsa mawonekedwe azitsulo apamwamba kwambiri, omwe amapereka mphamvu yolekanitsa mawiri awiri a ma electron-hole opangidwa ndi chithunzi. Kuthekera kwa mawonekedwewa kumatsogolera kuchokera ku YBCO kupita ku elekitirodi yachitsulo pomwe YBCO ikuchita mopitilira muyeso ndikusintha kupita kwina pomwe chitsanzocho chimakhala chosachita bwino. Chiyambi cha zomwe zingatheke chikhoza kugwirizanitsidwa mwachibadwa ndi zotsatira zapafupi14,15,16,17 pazitsulo-superconductor mawonekedwe pamene YBCO ndi superconducting ndipo mtengo wake uyenera kukhala ~ 10−8 mV pa 50 K ndi mphamvu ya laser ya 502 mW. /cm2. Kuphatikiza kwa zinthu zamtundu wa p YBCO pamalo abwinobwino okhala ndi mtundu wa n-mtundu wa Ag-paste mafomu, mwina, mphambano ya quasi-pn yomwe imayang'anira machitidwe a PV a zoumba za YBCO pa kutentha kwambiri. Zomwe taziwona zimawunikiranso momwe PV imayambira pa kutentha kwambiri kwapamwamba kwambiri kwa YBCO ceramics ndikutsegula njira yogwiritsira ntchito zida za optoelectronic monga chojambulira chowunikira mwachangu ndi zina.
Chithunzi 1a-c chikuwonetsa kuti mawonekedwe a IV a YBCO ceramic sampuli pa 50 K. Popanda kuunikira kowala, voteji kudutsa chitsanzocho imakhalabe pa zero ndi kusintha kwamakono, monga momwe tingayembekezere kuchokera ku superconducting material. Zotsatira zoonekeratu za photovoltaic zimawoneka pamene mtengo wa laser umalunjika ku cathode (mkuyu 1a): ma curves a IV omwe ali ofanana ndi I-axis amasunthira pansi ndikuwonjezeka kwa laser. Zikuwonekeratu kuti pali voteji yoyipa yopangidwa ndi zithunzi ngakhale popanda yapano (yomwe nthawi zambiri imatchedwa Open circuit voltage Voc). Kutsetsereka kwa zero kwa curve ya IV kukuwonetsa kuti chitsanzocho chikadali chachikulu kwambiri pakuwunikira kwa laser.
(a–c) ndi 300 K (e–g). Makhalidwe a V(I) adapezedwa posesa pakalipano kuchokera ku −10 mA mpaka +10 mA mu vacuum. Mbali yokha ya deta yoyesera imaperekedwa pofuna kumveka bwino. a, Mawonekedwe apano a YBCO amayezedwa ndi malo a laser omwe ali pa cathode (i). Ma curve onse a IV ndi mizere yopingasa yowongoka yomwe ikuwonetsa kuti chitsanzocho chikadali chachikulu kwambiri ndi kuwala kwa laser. Mapindikira amatsika ndikuwonjezereka kwamphamvu ya laser, kuwonetsa kuti pali mphamvu yoyipa (Voc) pakati pa ma voliyumu awiriwo ngakhale ndi zero pano. Mipiringidzo ya IV imakhalabe yosasinthika pamene laser imayendetsedwa pakati pa chitsanzo pa ether 50 K (b) kapena 300 K (f). Mzere wopingasa umayenda mmwamba pamene anode imawunikiridwa (c). Chithunzi chojambula chachitsulo chachitsulo-superconductor pa 50 K chikuwonetsedwa mu d. Mawonekedwe apano amtundu wa YBCO pa 300 K woyezedwa ndi laser mtengo woloza pa cathode ndi anode amaperekedwa mu e ndi g motsatana. Mosiyana ndi zotsatira za 50 K, malo otsetsereka opanda zero a mizere yowongoka amasonyeza kuti YBCO ili mu chikhalidwe chabwino; Makhalidwe a Voc amasiyana ndi kuwala kowala kumbali ina, kusonyeza njira yosiyana yolekanitsa. Mawonekedwe otheka a mawonekedwe pa 300 K akuwonetsedwa mu hj Chithunzi chenicheni cha chitsanzo chokhala ndi zitsogozo.
YBCO yolemera kwambiri ya okosijeni yomwe ili m'boma la superconducting imatha kuyamwa pafupifupi kuwala kwadzuwa chifukwa cha kusiyana kwake kochepa kwambiri kwa mphamvu (Mwachitsanzo)9,10, potero kumapanga awiriawiri a ma elekitironi-bowo (e–h). Kuti apange voteji yotseguka ya Voc poyamwitsa ma photon, ndikofunikira kulekanitsa ma eh awiriawiri opangidwa ndi zithunzi kusanachitike18. The zoipa Voc, wachibale cathode ndi anode monga zikusonyezedwa mkuyu. 1i, zikusonyeza kuti pali mphamvu magetsi kudutsa zitsulo-superconductor mawonekedwe, amene amasesa ma elekitironi kwa anode ndi mabowo kwa cathode. Ngati ndi choncho, payeneranso kuti pakhale nsonga yolozera kuchokera ku superconductor kupita ku electrode yachitsulo pa anode. Chifukwa chake, Voc yabwino ingapezeke ngati gawo lachitsanzo pafupi ndi anode liwunikiridwa. Kuphatikiza apo, pasakhale ma voltages opangidwa ndi zithunzi pomwe malo a laser akulozedwera kumadera akutali ndi ma elekitirodi. Zilidi choncho monga momwe tikuonera mkuyu 1b,c!.
Pamene kuwala kumayenda kuchokera ku cathode electrode kupita pakati pa chitsanzo (pafupifupi 1.25 mm kutali ndi mawonekedwe), palibe kusiyana kwa ma curve a IV ndipo palibe Voc yomwe ingakhoze kuwonedwa ndi kuwonjezeka kwa laser mwamphamvu mpaka pamtengo wokwanira womwe ulipo (mkuyu 1b) . Mwachibadwa, chotsatirachi chikhoza kufotokozedwa ndi moyo wochepa wa zonyamulira zojambulidwa ndi zithunzi komanso kusowa kwa mphamvu yolekanitsa mu chitsanzo. Mapeyala a ma elekitironi amatha kupangidwa nthawi iliyonse pamene chitsanzocho chaunikira, koma ma e-h awiriawiri ambiri adzawonongedwa ndipo palibe photovoltaic effect yomwe imawonedwa ngati malo a laser agwera kumadera akutali ndi ma elekitirodi aliwonse. Kusuntha malo a laser ku ma electrode a anode, ma curves a IV omwe ali ofanana ndi I-axis amasunthira mmwamba ndikuwonjezera mphamvu ya laser (mkuyu 1c). Malo amagetsi ofananirako omwe amamangidwanso amakhalapo pamphambano yachitsulo-superconductor pa anode. Komabe, ma elekitirodi azitsulo amalumikizana ndi njira yabwino yoyeserera nthawi ino. Mabowo opangidwa ndi laser amakankhidwira ku anode lead ndipo motero Voc yabwino imawonedwa. Zotsatira zomwe zaperekedwa pano zimapereka umboni wamphamvu wosonyeza kuti palidi mawonekedwe omwe angaloze kuchokera ku superconductor kupita ku electrode yachitsulo.
Photovoltaic effect mu YBa2Cu3O6.96 ceramics pa 300 K ikuwonetsedwa mu Chithunzi 1e-g. Popanda kuwunikira, IV yokhotakhota yachitsanzo ndi mzere wowongoka womwe umadutsa poyambira. Mzere wowongokawu umayenda mmwamba molingana ndi choyambirira ndikuwonjezera mphamvu ya laser irradiating pamayendedwe a cathode (mkuyu 1e). Pali milandu iwiri yochepetsera chidwi pa chipangizo cha photovoltaic. Mkhalidwe waufupi umachitika pamene V = 0. Zomwe zilipo panopa zimatchulidwa kuti nthawi yochepa (Isc). Mlandu wachiwiri wolepheretsa ndi mawonekedwe otseguka (Voc) omwe amapezeka pamene R→∞ kapena panopa ndi ziro. Chithunzi 1e chikuwonetseratu kuti Voc ndi yabwino ndipo imawonjezeka ndi kuwonjezereka kwa kuwala, mosiyana ndi zotsatira zomwe zimapezeka pa 50 K; pomwe Isc yoyipa ikuwoneka kuti ikukulirakulira ndi kuunikira kowala, khalidwe lodziwika bwino la maselo adzuwa.
Mofananamo, pamene mtanda wa laser umalozedwera kumadera omwe ali kutali ndi ma electrodes, V (I) curve imakhala yodziimira pa mphamvu ya laser ndipo palibe photovoltaic effect yomwe inawonekera (mkuyu 1f). Mofanana ndi muyeso wa 50 K, ma curve a IV amapita ku mbali ina pamene electrode ya anode imayatsidwa (mkuyu 1g). Zotsatira zonsezi zomwe zapezedwa pamtundu uwu wa YBCO-Ag paste pa 300 K wokhala ndi laser yoyatsidwa pamalo osiyanasiyana achitsanzo zimagwirizana ndi mawonekedwe owoneka mosiyana ndi omwe amawonedwa pa 50 K.
Ambiri ma elekitironi condense mu Cooper awiriawiri mu superconducting YBCO pansi kusintha kutentha Tc. Ali mu electrode yachitsulo, ma elekitironi onse amakhalabe mawonekedwe amodzi. Pali kachulukidwe kakang'ono ka ma elekitironi onse awiri ndi ma Cooper awiriawiri pafupi ndi mawonekedwe achitsulo-superconductor. Ma elekitironi ambiri omwe amanyamula ma elekitironi muzinthu zachitsulo adzafalikira kudera la superconductor, pomwe ambiri onyamula Cooper-awiri m'chigawo cha YBCO adzafalikira kudera lachitsulo. Pamene Cooper awiriawiri onyamula milandu zambiri ndi kukhala ndi kuyenda lalikulu kuposa ma elekitironi mmodzi diffuse kuchokera YBCO mu chigawo zitsulo, maatomu zabwino nachimwira amasiyidwa, chifukwa mu munda magetsi mu danga mlandu dera. Chitsogozo cha gawo lamagetsi ichi chikuwonetsedwa mu chithunzi cha schema Fig. 1d. Kuwala kwa fotoni pafupi ndi malo opangira danga kumatha kupanga ma eh awiriawiri omwe angasiyanitsidwe ndikusesedwa ndikupanga chithunzithunzi cholowera m'mbuyo. Ma elekitironi atangotuluka m'munda wamagetsi, amafupikitsidwa kukhala awiriawiri ndikuyenderera ku electrode ina popanda kukana. Pankhaniyi, Voc ikutsutsana ndi polarity yokhazikitsidwa kale ndipo imasonyeza mtengo woipa pamene mtengo wa laser umaloza kudera lozungulira electrode yolakwika. Kuchokera pa mtengo wa Voc, kuthekera kudutsa mawonekedwe angayerekezedwe: mtunda pakati pa magetsi awiri d ndi ~ 5 × 10-3 m, makulidwe a mawonekedwe achitsulo-superconductor, di, ayenera kukhala ofanana ndi kukula kwake. monga kutalika kwa mgwirizano wa YBCO superconductor (~1 nm)19,20, tengani mtengo wa Voc = 0.03 mV, ma Vms omwe angakhalepo pa mawonekedwe achitsulo-superconductor amawunikidwa kukhala ~ 10−11 V pa 50 K ndi mphamvu ya laser ya 502 mW/cm2, pogwiritsa ntchito equation,
Tikufuna kutsindika apa kuti magetsi opangidwa ndi chithunzi sangathe kufotokozedwa ndi chithunzi cha kutentha. Zatsimikiziridwa moyesera kuti chiwongolero cha Seebeck cha superconductor YBCO ndi Ss = 021. Chigawo cha Seebeck cha mawaya amkuwa ali mumtundu wa SCu = 0.34-1.15 μV / K3. Kutentha kwa waya wamkuwa pamalo a laser kumatha kukwezedwa pang'ono ndi 0.06 K ndi mphamvu yayikulu ya laser yomwe ikupezeka pa 50 K. Izi zitha kupanga mphamvu ya thermoelectric ya 6.9 × 10−8 V yomwe ndi maoda atatu ocheperako kuposa Voc yopezeka mu Chithunzi 1 (a). Zikuwonekeratu kuti zotsatira za thermoelectric ndizochepa kwambiri kuti zifotokoze zotsatira zoyesera. M'malo mwake, kusiyanasiyana kwa kutentha chifukwa cha kuwala kwa laser kutha kutha pasanathe mphindi imodzi kuti chopereka chochokera kumatenthedwe chitha kunyalanyazidwa.
Izi photovoltaic zotsatira za YBCO kutentha kwa chipinda zimasonyeza kuti njira yosiyana yolekanitsa ndalama ikukhudzidwa pano. Superconducting YBCO mu chikhalidwe chabwino ndi p-mtundu zakuthupi ndi mabowo monga chonyamulira22,23, pamene zitsulo Ag-phala ali ndi makhalidwe a n-mtundu zakuthupi. Mofanana ndi pn mphambano, kufalikira kwa ma elekitironi mu phala siliva ndi mabowo YBCO ceramic kupanga mkati magetsi munda akulozera ku YBCO ceramic pa mawonekedwe (mkuyu. 1h). Ndilo gawo lamkati ili lomwe limapereka mphamvu yolekanitsa ndipo limatsogolera ku Voc yabwino ndi Isc yoipa kwa dongosolo la phala la YBCO-Ag pa kutentha kwa firiji, monga momwe tawonetsera mkuyu 1e. Kapenanso, Ag-YBCO ikhoza kupanga mphambano ya p-type Schottky yomwe imatsogoleranso ku mawonekedwe owoneka bwino omwe ali ndi polarity yofanana ndi yomwe ili pamwamba24.
Kufufuza mwatsatanetsatane chisinthiko ndondomeko ya katundu photovoltaic pa superconducting kusintha kwa YBCO, IV zokhotakhota chitsanzo pa 80 K anayesedwa ndi osankhidwa laser intensities kuunikira pa cathode elekitirodi (mkuyu. 2). Popanda laser walitsa, voteji kudutsa chitsanzo amasunga pa ziro mosasamala kanthu panopa, kusonyeza superconducting boma chitsanzo pa 80 K (mkuyu. 2a). Mofanana ndi deta yomwe imapezeka pa 50 K, ma curves a IV omwe ali ofanana ndi I-axis amasunthira pansi ndi kuwonjezeka kwa laser intensity mpaka mtengo wovuta kwambiri wa Pc wafika. Pamwamba pa laser intensity yovuta kwambiri (Pc), superconductor imasintha kuchokera ku gawo la superconducting kupita ku gawo lotsutsa; voteji imayamba kuwonjezeka ndi panopa chifukwa cha kukana mu superconductor. Chotsatira chake, chigawo cha IV chimayamba kugwirizanitsa ndi I-axis ndi V-axis yomwe imatsogolera ku Voc yoipa ndi Isc yabwino poyamba. Tsopano chitsanzocho chikuwoneka kuti chili mu chikhalidwe chapadera chomwe polarity ya Voc ndi Isc imakhudzidwa kwambiri ndi kuwala kwamphamvu; ndi kuwonjezeka kochepa kwambiri kwa kuwala kwamphamvu Isc imasinthidwa kuchoka ku zabwino kupita ku zoipa ndi Voc kuchokera ku zoipa kupita ku mtengo wabwino, kudutsa chiyambi (kutengeka kwakukulu kwa photovoltaic properties, makamaka mtengo wa Isc, kuunikira kowala kungawoneke bwino mu Fig. 2b). Pamphamvu kwambiri ya laser yomwe ilipo, ma curve a IV amayenera kufananiza, kuwonetsa momwe zitsanzo za YBCO zilili.
Pakati pa laser spot imayikidwa mozungulira ma electrode a cathode (onani mkuyu 1i). a, IV mapindikidwe a YBCO amawunikiridwa ndi mphamvu zosiyanasiyana za laser. b (pamwamba), Kudalira kwamphamvu kwa Laser kwa voc voc yotseguka ndi dera lalifupi lapano Isc. Makhalidwe a Isc sangathe kupezedwa pang'onopang'ono (<110 mW / cm2) chifukwa ma curve a IV amafanana ndi I-axis pamene chitsanzocho chiri mu superconducting state. b (pansi), kukana kusiyanitsa ngati ntchito yamphamvu ya laser.
Kudalira kwamphamvu kwa laser kwa Voc ndi Isc pa 80 K kukuwonetsedwa mu Chithunzi 2b (pamwamba). The photovoltaic katundu akhoza kukambidwa m'madera atatu kuwala kwambiri. Dera loyamba liri pakati pa 0 ndi Pc, momwe YBCO ndi superconducting, Voc ndi yoipa ndipo imachepa (kuwonjezeka kwamtengo wapatali) ndi kuwala kowala ndikufikira pang'ono pa PC. Chigawo chachiwiri chimachokera ku Pc kupita ku mphamvu ina yofunika kwambiri P0, momwe Voc imawonjezeka pamene Isc imatsika ndi kuwonjezereka kwa kuwala ndipo onse amafika zero pa P0. Dera lachitatu liri pamwamba pa P0 mpaka momwe YBCO idafikira. Ngakhale onse awiri Voc ndi Isc amasiyana ndi kuwala kowala mofanana ndi dera 2, ali ndi polarity yosiyana pamwamba pa kulimba kwambiri P0. Kufunika kwa P0 kumakhala kuti palibe photovoltaic effect ndipo njira yolekanitsa ndalama imasintha bwino panthawiyi. Zitsanzo za YBCO zimakhala zosagwirizana kwambiri ndi kuchuluka kwa kuwala kotereku koma momwe zilili bwino kuti zifikidwe.
Mwachiwonekere, mawonekedwe a photovoltaic a dongosololi amagwirizana kwambiri ndi superconductivity ya YBCO ndi kusintha kwake kwakukulu. Kusiyanitsa kosiyana, dV / dI, ya YBCO ikuwonetsedwa mu Chithunzi 2b (pansi) monga ntchito ya mphamvu ya laser. Monga tanenera kale, kumanga-mu mphamvu magetsi mu mawonekedwe chifukwa Cooper awiri mfundo diffusion kuchokera superconductor zitsulo. Zofanana ndi zomwe zimawonedwa pa 50 K, mphamvu ya photovoltaic imakulitsidwa ndikuwonjezera mphamvu ya laser kuchokera ku 0 kupita ku PC. Pamene mphamvu ya laser ikufika pamtengo pang'ono pamwamba pa Pc, mphuno ya IV imayamba kugwedezeka ndipo kukana kwa chitsanzo kumayamba kuonekera, koma polarity ya mawonekedwe a mawonekedwe sichinasinthidwebe. Zotsatira za chisangalalo cha kuwala pa superconductivity zafufuzidwa m'dera lowoneka kapena pafupi ndi IR. Ngakhale njira yayikulu ndikuphwanya awiriawiri a Cooper ndikuwononga superconductivity25,26, nthawi zina kusintha kwa superconductivity kumatha kukulitsidwa27,28,29, magawo atsopano a superconductivity amathanso kupangitsidwa30. Kusapezeka kwa superconductivity pa PC kumatha kukhala chifukwa chakusweka kwa awiriwa. Pofika P0, kuthekera kudutsa mawonekedwewo kumakhala ziro, kusonyeza kuti kachulukidwe kawo kachulukidwe mbali zonse za mawonekedwe amafika pamlingo womwewo pansi pa kulimba uku kwakuunika. Kuwonjezeka kwina kwa mphamvu ya laser kumapangitsa kuti awiriawiri a Cooper awonongeke ndipo YBCO imasinthidwa pang'onopang'ono kukhala p-mtundu wa zinthu. M'malo electron ndi Cooper awiri diffusion, mbali ya mawonekedwe tsopano anatsimikiza ndi elekitironi ndi dzenje diffusion amene amatsogolera ku kusintha polarity munda magetsi mu mawonekedwe ndipo chifukwa chake Voc zabwino (yerekezerani Fig.1d, h). Pamphamvu kwambiri ya laser, kukana kosiyana kwa YBCO kumadzaza pamtengo wolingana ndi momwe zilili bwino ndipo onse a Voc ndi Isc amatha kusiyanasiyana mosiyanasiyana ndi mphamvu ya laser (mkuyu 2b). Kuwonetsetsa uku kukuwonetsa kuti kuwala kwa laser pamtundu wabwinobwino YBCO sikudzasinthanso mphamvu yake yolimbana ndi mawonekedwe azitsulo zachitsulo koma kumangowonjezera kuchuluka kwa ma electron-hole awiriawiri.
Kuti afufuze zotsatira za kutentha pa photovoltaic katundu, zitsulo-superconductor dongosolo anayatsa pa cathode ndi blue laser mphamvu 502 mW / cm2. Mapiritsi a IV omwe amapezeka pa kutentha kosankhidwa pakati pa 50 ndi 300 K amaperekedwa mkuyu. Voc yotseguka yamagetsi Voc, Isc yochepa yapano ndi kukana kosiyana kumatha kupezeka kuchokera ku ma curve awa a IV ndipo akuwonetsedwa mkuyu 3b. Popanda kuunikira kuwala, ma curve onse a IV omwe amayezedwa pa kutentha kosiyanasiyana amadutsa chiyambi monga momwe amayembekezera (chithunzi cha 3a). Makhalidwe a IV amasintha kwambiri ndi kutentha kowonjezereka pamene kachitidweko kawunikiridwa ndi mtengo wamphamvu wa laser (502 mW/cm2). Pakutentha kotsika ma curve a IV amakhala mizere yowongoka yofananira ndi I-axis yokhala ndi malingaliro oyipa a Voc. Mzerewu umayenda m'mwamba ndi kutentha kowonjezereka ndipo pang'onopang'ono umasanduka mzere wokhala ndi malo otsetsereka a Nonzero pa kutentha kwakukulu kwa Tcp (Mkuyu 3a (pamwamba)). Zikuwoneka kuti zokhotakhota zonse za IV zimazungulira mozungulira gawo lachitatu. Voc imakwera kuchoka pamtengo woyipa kupita pamtengo wabwino pomwe Isc imatsika kuchokera pazabwino kupita pamtengo woipa. Pamwamba pa kutentha koyambirira kwa superconducting kusintha Tc wa YBCO, IV pamapindikira amasintha mosiyana ndi kutentha (pansi pa mkuyu. 3a). Choyamba, malo ozungulira a ma curve a IV amasunthira ku quadrant yoyamba. Kachiwiri, Voc ikucheperachepera ndipo Isc ikuwonjezeka ndi kutentha kwakukulu (pamwamba pa mkuyu 3b). Chachitatu, kutsetsereka kwa ma curve a IV kumawonjezeka molingana ndi kutentha komwe kumapangitsa kuti pakhale kutentha kwabwino kwa YBCO (pansi pa Chithunzi 3b).
Kudalira kwa kutentha kwa mawonekedwe a photovoltaic a YBCO-Ag paste system pansi pa 502 mW/cm2 laser kuwala.
Pakati pa laser spot imayikidwa mozungulira ma electrode a cathode (onani mkuyu 1i). a, IV zokhotakhota anapezedwa 50 kuti 90 K (pamwamba) ndi 100 kuti 300 K (pansi) ndi kutentha increment 5 K ndi 20 K, motero. Inset a ikuwonetsa mawonekedwe a IV pa kutentha kosiyanasiyana mumdima. Zokhotakhota zonse zimadutsa poyambira. b, voteji yotseguka ya Voc ndi Isc (pamwamba) ndi kukana kosiyana, dV/dI, ya YBCO (pansi) ngati ntchito ya kutentha. Kutentha kwa zero kukana kwa superconducting kusintha kwa Tcp sikuperekedwa chifukwa kuli pafupi kwambiri ndi Tc0.
Kutentha kutatu koopsa kumatha kudziwika kuchokera ku Chithunzi 3b: Tcp, pamwamba pake YBCO imakhala yosakhala ya superconducting; Tc0, pomwe onse a Voc ndi Isc amakhala ziro ndi Tc, kutentha koyambira kopitilira muyeso kwa YBCO popanda kuwala kwa laser. Pansi pa Tcp ~ 55 K, YBCO yoyatsidwa ndi laser ili mu superconducting state yokhala ndi ma Cooper awiriawiri. Zotsatira za kuwala kwa laser ndi kuchepetsa zero resistance superconducting transition kutentha kuchokera ku 89 K mpaka ~ 55 K (pansi pa Mkuyu 3b) mwa kuchepetsa mgwirizano wa Cooper pair kuphatikizapo kupanga photovoltaic voltage ndi panopa. Kutentha kowonjezereka kumaphwanyanso mawiri a Cooper omwe amatsogolera ku mphamvu yotsika mu mawonekedwe. Chifukwa chake, mtengo wathunthu wa Voc udzakhala wocheperako, ngakhale mphamvu yofananira ya kuwala kwa laser imagwiritsidwa ntchito. Kuthekera kwa mawonekedwe kudzakhala kochepa komanso kocheperako ndikuwonjezeka kwina kwa kutentha ndikufikira ziro pa Tc0. Palibe photovoltaic effect pa mfundo yapaderayi chifukwa palibe munda wamkati wolekanitsa awiriawiri opangidwa ndi electron-hole. Kusintha kwa polarity kwa zomwe zingatheke kumachitika pamwamba pa kutentha kwakukulu kumeneku chifukwa mphamvu yaulere mu Ag paste ndi yaikulu kuposa ya YBCO yomwe imasamutsidwa pang'onopang'ono kubwerera ku p-type. Pano tikufuna kutsindika kuti kusintha kwa polarity kwa Voc ndi Isc kumachitika mwamsanga pambuyo pa kusintha kwa zero kukana kwa superconducting, mosasamala kanthu za chifukwa cha kusintha. Kuwonetsetsa uku kumasonyeza momveka bwino, kwa nthawi yoyamba, mgwirizano pakati pa superconductivity ndi zotsatira za photovoltaic zomwe zimagwirizana ndi zitsulo-superconductor mawonekedwe. Mkhalidwe wa kuthekera uku kudutsa mawonekedwe achitsulo a superconductor-wabwinobwino akhala akufufuza kwazaka makumi angapo zapitazi koma pali mafunso ambiri omwe akuyembekezerabe kuyankhidwa. Kuyeza kwa mphamvu ya photovoltaic kungakhale njira yabwino yowunikira tsatanetsatane (monga mphamvu zake ndi polarity etc.) za kuthekera kofunikiraku ndipo motero kuwunikira kutentha kwapamwamba kwa superconducting proximity effect.
Kuwonjezeka kwina kwa kutentha kuchokera ku Tc0 kupita ku Tc kumadzetsa kuchulukirachulukira kwa ma Cooper awiriawiri komanso kupititsa patsogolo mawonekedwe a mawonekedwe ndipo motero Voc yayikulu. Ku Tc gulu la Cooper ndende limakhala ziro ndipo kuthekera komanganso pamawonekedwe kumafika pachimake, zomwe zimapangitsa kuti pakhale Voc yayikulu ndi Isc yochepa. Kuwonjezeka kofulumira kwa Voc ndi Isc (mtheradi wamtengo wapatali) mumtundu wa kutentha uku kumagwirizana ndi kusintha kwa superconducting komwe kumakulitsidwa kuchokera ku ΔT ~ 3 K mpaka ~ 34 K ndi laser irradiation of intensity 502 mW / cm2 (Mkuyu 3b). M'madera omwe ali pamwamba pa Tc, magetsi otseguka a Voc amachepetsa ndi kutentha (pamwamba pa mkuyu 3b), mofanana ndi khalidwe la Voc la maselo abwino a dzuwa lochokera ku pn junctions31,32,33. Ngakhale kuti kusintha kwa Voc ndi kutentha (−dVoc/dT), komwe kumadalira kwambiri mphamvu ya laser, kumakhala kochepa kwambiri kusiyana ndi maselo a dzuwa, kutentha kwa Voc kwa YBCO-Ag mphambano kumakhala ndi dongosolo lofanana la kukula kwake. ma cell a solar. Kuthamanga kwaposachedwa kwa pn mphumu ya chipangizo chodziwika bwino cha solar kumawonjezeka ndi kutentha, zomwe zimapangitsa kuchepa kwa Voc pamene kutentha kumawonjezeka. Ma curve ozungulira a IV omwe amawonedwa ndi dongosolo ili la Ag-superconductor, chifukwa choyamba mawonekedwe ang'onoang'ono a mawonekedwe ndipo kachiwiri kulumikizidwa kumbuyo ndi kumbuyo kwa ma heterojunctions awiri, kumapangitsa kuti zikhale zovuta kudziwa kutayikira kwapano. Komabe, zimasokonekera kwambiri kuti kutentha komweko kwa kutayikira kwapano kumayambitsa machitidwe a Voc omwe adawonedwa pakuyesa kwathu. Malinga ndi tanthauzoli, Isc ndiyomwe ikufunika kuti ipange magetsi oyipa kuti alipire Voc kuti mphamvu yonseyi ikhale zero. Kutentha kumawonjezeka, Voc imakhala yaying'ono kotero kuti pakali pano pakufunika kuti pakhale mpweya woipa. Kuwonjezera apo, kukana kwa YBCO kumawonjezeka mofanana ndi kutentha pamwamba pa Tc (pansi pa Mkuyu 3b), zomwe zimathandizanso kuti zikhale zochepa kwambiri za Isc pa kutentha kwakukulu.
Zindikirani kuti zotsatira zomwe zaperekedwa mu Mkuyu 2,3 zimapezedwa ndi laser irradiating pamalo ozungulira ma cathode electrode. Miyezo yabwerezedwanso ndi laser malo omwe ali pa anode ndi mawonekedwe a IV ofanana ndi mawonekedwe a photovoltaic awonedwa kupatulapo kuti polarity ya Voc ndi Isc yasinthidwa pankhaniyi. Deta yonseyi imayambitsa njira ya photovoltaic effect, yomwe imagwirizana kwambiri ndi mawonekedwe a superconductor-metal.
Mwachidule, mawonekedwe a IV a laser irradiated superconducting YBCO-Ag paste system adayesedwa ngati ntchito za kutentha ndi mphamvu ya laser. Chodabwitsa cha photovoltaic effect chawonedwa mu kutentha kwa 50 mpaka 300 K. Amapezeka kuti zinthu za photovoltaic zimagwirizana kwambiri ndi superconductivity ya YBCO ceramics. Kusintha kwa polarity kwa Voc ndi Isc kumachitika nthawi yomweyo pambuyo pakusintha kopitilira muyeso kopanda chithunzi. Kudalira kwa kutentha kwa Voc ndi Isc kuyeza mphamvu ya laser yokhazikika kukuwonetsanso kusintha kosiyana kwa polarity pa kutentha koopsa pamwamba pomwe chitsanzocho chimakhala chosasunthika. Popeza malo a laser kumadera osiyanasiyana a chitsanzo, tikuwonetsa kuti pali mphamvu yamagetsi panjira yolumikizirana, yomwe imapereka mphamvu yolekanitsa mawiri awiri opangidwa ndi ma elekitironi. Kuthekera kwa mawonekedwewa kumatsogolera kuchokera ku YBCO kupita ku elekitirodi yachitsulo pomwe YBCO ikuchita mopitilira muyeso ndikusintha kupita kwina pomwe chitsanzocho chimakhala chosachita bwino. Chiyambi cha zomwe zingatheke chingakhale chogwirizana ndi kuyandikira kwa mawonekedwe azitsulo-superconductor pamene YBCO ndi superconducting ndipo akuti ndi ~ 10−8 mV pa 50 K ndi mphamvu ya laser ya 502 mW/cm2. Kulumikizana kwa p-mtundu wa YBCO pamalo abwinobwino okhala ndi mtundu wa n-Ag-paste amapanga mphambano ya quasi-pn yomwe imayang'anira mawonekedwe a photovoltaic a YBCO ceramics pa kutentha kwakukulu. Zomwe taziwona pamwambapa zikuwunikira mphamvu ya PV pakutentha kwapamwamba kwambiri kwa YBCO ceramics ndikutsegula njira yopitira kuzinthu zatsopano pazida za optoelectronic monga chojambulira chowunikira komanso chowunikira chimodzi.
Kuyesera kwa photovoltaic effect kunachitika pa YBCO ceramic chitsanzo cha makulidwe a 0.52 mm ndi 8.64 × 2.26 mm2 mawonekedwe amakona anayi ndikuunikira ndi laser blue-laser yosalekeza (λ = 450 nm) yokhala ndi mawanga a laser kukula kwa 1.25 mm mu radius. Kugwiritsa ntchito zochulukira m'malo mwa filimu yopyapyala kumatithandiza kuphunzira za photovoltaic za superconductor popanda kuthana ndi zovuta zovuta za gawo lapansi6,7. Kuphatikiza apo, zinthu zambiri zitha kukhala zothandiza pakukonzekera kwake kosavuta komanso zotsika mtengo. Mawaya otsogolera amkuwa amalumikizidwa pachitsanzo cha YBCO ndi phala lasiliva lomwe limapanga maelekitirodi anayi ozungulira pafupifupi 1 mm m'mimba mwake. Mtunda pakati pa ma electrode awiri amagetsi ndi pafupifupi 5 mm. Makhalidwe a IV a chitsanzo adayezedwa pogwiritsa ntchito magnetometer ya vibration (VersaLab, Quantum Design) yokhala ndi zenera la quartz crystal. Njira yokhazikika yamawaya anayi idagwiritsidwa ntchito kupeza ma curve a IV. Malo achibale a maelekitirodi ndi malo a laser akuwonetsedwa mkuyu.
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Ntchitoyi yathandizidwa ndi National Natural Science Foundation ya China (Grant No. 60571063), Ntchito Zofufuza Zofunikira za Province la Henan, China (Grant No. 122300410231).
FY inalemba zolemba za pepalalo ndipo MYH inakonza chitsanzo cha YBCO ceramic. FY ndi MYH adayesa kuyesa ndikusanthula zotsatira. FGC inatsogolera polojekitiyi komanso kutanthauzira kwasayansi kwa deta. Olemba onse adawunikiranso zolembazo.
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Yang, F., Han, M. & Chang, F. Chiyambi cha photovoltaic effect mu superconducting YBa2Cu3O6.96 ceramics. Sci Rep 5, 11504 (2015). https://doi.org/10.1038/srep11504
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Nthawi yotumiza: Apr-22-2020