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Say defect passivation et malaknab ya uusaren pian napaaligwas so performance na lead triiodide perovskite solar cells, balet say epekto na nanduruman depekto ed α-phase stability et agni malinew; Dia, diad pangusar na density functional theory, nabirbir tayo ed primeron pankanawnawa so dalan na inkaderal na formamidine lead triiodide perovskite manlapud α-phase ya anggad δ-phase tan aralen tayo so epekto na nanduruman depekto ed phase transition energy barrier. Say resulta na simulation et mangipapasakbay ya saray bakantin iodine so mas posiblin pansengegan na pakaderal lapud signipikantin mamaabeba ed energy barrier parad α-δ phase transition tan walaan na sankaabebaan ya enerhiya na formation diad tapew na perovskite. Say pangiloob na makapal a layer na ag-ontutunaw ed danum ya lead oxalate ed tapew na perovskite et makabkabaliksan ya mangamper ed inkabulok na α-phase, ya mangamper ed iyalis tan iyalis na iodine. Niarum ni, sayan estratehiya so makabkabaliksan a mamawas ed interfacial nonradiative recombination tan mamaaligwas ed inkaepektibo na solar cell ya anggad 25.39% (sertipikadon 24.92%). Say ag-akabalot ya kagawaan et makapansiansia nin siansia ed orihinal ya 92% ya inkaepektibo to kayari na pan-operate to ed sankatageyan ya pakayari ed loob na 550 oras diad silong na simulated 1.5 G ya air mass irradiation.
Say power conversion efficiency (PCE) na perovskite solar cells (PSCs) et akasabi ed sertipikadon sankatageyan ya 26%1. Manlapu nen 2015, mas labay na saray modernon PSC so formamidine triiodide perovskite (FAPbI3) bilang sakey a light-absorbing layer lapud ekselentin thermal stability tan mas labay ton bandgap ya asingger ed Shockley-Keisser limit ya 2,3,4. Makapaermen ta saray FAPbI3 films et thermodynamically ondalan ed phase transition manlapud andeket ya α phase ya anggad duyaw ya aliwan perovskite δ phase diad temperatura na kuarto5,6. Pian naprebentaan so pakaporma na delta phase, nanduruman komplikadon komposisyon na perovskite so ginawa. Say sankabaloan ya estratehiya pian natalonaan iyan problema et say pangilaok na FAPbI3 ed kombinasyon na methyl ammonium (MA+), cesium (Cs+) tan bromide (Br-) ions7,8,9. Balet, saray hybrid perovskites et mansasakit lapud bandgap broadening tan photoinduced phase separation, ya mamapaermen ed performance tan operational stability na resulta na PSCs10,11,12.
Impanengneng na saray agano nin impanaral ya say puron single crystal FAPbI3 ya anggapoy antokaman ya doping et walaan na ekselentin inkapekder lapud ekselentin inkakristal tan abeban depekto to13,14. Kanian, say pambawas ed saray depekto diad pamarakep ed inkakristal na bulk FAPbI3 et sakey ya importantin estratehiya pian nadampot so epektibo tan malet ya PSCs2,15. Balet, legan na operasyon na FAPbI3 PSC, nayarin nagawa nin siansia so pakaderal na aglabay ya duyaw ya hexagonal ya aliwan perovskite δ phase16. Say proseso et kaslakan ya onggapo ed saray tapew tan ketegan na bukel ya mas mainomay ya naapektoan na danum, petang tan liwawa lapud dakel so depektibon lugar17. Kanian, nakaukolan so surface/grain passivation pian napabiskeg so black phase na FAPbI318. Dakel ya estratehiya ed panag-passive na depekto, kaiba lay pangiloob na low-dimensional perovskites, acid-base Lewis molecules, tan ammonium halide salts, so akagawa na baleg ya inyaligwas ed formamidine PSCs19,20,21,22. Anggad natan, ngalngalin amin ya impanaral et akasentro ed papel na nanduruman depekto ed pakadetermina na saray optoelectronic properties a singa say carrier recombination, diffusion length tan band structure ed solar cells22,23,24. Singa bilang, say density functional theory (DFT) et uusaren pian nahulaan so enerhiya na pormasyon tan saray lebel na enerhiya na panag-trap na nanduruman depekto, ya malaknab ya uusaren pian mangigiya ed praktikal a desinyo na passivation20,25,26. No ondarakel so depekto, kaslakan ya onaaralem so inkapekder na kagawaan. Balet, diad formamidine PSCs, say mekanismo na impluensya na nanduruman depekto ed phase stability tan photoelectric properties et nepeg ya sigpot ya duma. Diad sankaabigan ya amta mi, say manunan pakatalos no panon ya saray depekto so mangiiter na cubic ya anggad hexagonal (α-δ) ya phase transition tan say papel na surface passivation ed phase stability na α-FAPbI3 perovskite et ag ni natalosan.
Dia, ipaparungtal mi so dalan na inkagba na FAPbI3 perovskite manlapud black α-phase ya anggad yellow δ-phase tan say impluensya na nanduruman depekto ed energy barrier na α-to-δ-phase transition panamegley na DFT. Saray bakantin I, ya mainomay ya nagawa legan na panaggawa na pelikula tan panag-operate na kagawaan, so naisip ya mas posiblin mangigapo na α-δ phase transition. Kanian, inloob mi so ag-ontutunaw ed danum tan malet ed kemikal ya makapal a layer na lead oxalate (PbC2O4) ed tapew na FAPbI3 panamegley na in situ a reaksion. Say lead oxalate surface (LOS) et mangaamper ed pakaporma na saray I vacancies tan mangamper ed iyalis na I ions no na-stimulate na petang, liwawa, tan electric fields. Say resulta na LOS et makabkabaliksan ya mamapaabeba ed interfacial nonradiative recombination tan mamaaligwas ed FAPbI3 PSC efficiency ya anggad 25.39% (nasertipikaan ed 24.92%). Say unpackaged LOS device et nansiansia na 92% na orihinal ya inkaepektibo to kayari ton nan-operate ed maximum power point (MPP) ed loob na masulok ya 550 oras diad simulated air mass (AM) ya 1.5 G na radiation.
Inmuna min ginawa so ab initio ya kalkulasyon pian naamtaan so dalan na inkabulok na FAPbI3 perovskite pian makaalis manlapud α phase ya anggad δ phase. Diad panamegley na detalyadon proseso na phase transformation, naimano ya say pananguman manlapud three-dimensional corner-sharing [PbI6] octahedron ed cubic α-phase na FAPbI3 ya anggad one-dimensional edge-sharing [PbI6] octahedron ed hexagonal δ-phase na FAPbI3 et nagawaan. breaking 9. Say Pb-I et manporma na bond ed unonan kundang (Int-1), tan say energy barrier to et onsabi ed 0.62 eV/cell, a singa nanengneng ed Figure 1a. No say octahedron et iyalis ed [0\(\bar{1}\)1] ya direksion, say hexagonal ya antikey a kadena et onlaknab manlapud 1×1 ya anggad 1×3, 1×4 tan diad kaunoran et onloob ed δ phase. Say orientation ratio na interon dalan et (011)α//(001)δ + [100]α//[100]δ. Manlapud energy distribution diagram, nanengneng ya kayari na nucleation na δ phase na FAPbI3 ed ontumbok iran yugtan, say energy barrier et abeba nen say α phase transition, ya mankabaliksan ya say phase transition et maples. Malinew, say unonan kundang ed panangontrol ed phase transition et importante no labay tayon naekal so α-phase degradation.
a Proseso na Phase transformation manlapud kawigi ya anggad kawanan – andeket ya FAPbI3 phase (α-phase), unonan Pb-I bond cleavage (Int-1) tan kaaruman ya Pb-I bond cleavage (Int-2, Int -3 tan Int -4) tan yellow phase FAPbI3 (delta phase). b Saray babeng ed enerhiya ed α ya anggad δ ya phase transition na FAPbI3 base ed nanduruman intrinsic point defects. Say tuldok-tuldok a linya so mangipapanengneng na enerhiya na sakey ya ideyal a kristal (0.62 eV). c Enerhiya na inkaporma na manunan depekto ed tapew na lead perovskite. Say abscissa axis et say energy barrier na α-δ phase transition, tan say ordinate axis et say enerhiya na depekto. Saray parte ya aka-shade na grey, yellow tan green et say type I (abeban EB-atagey ya FE), type II (atagey ya FE) tan type III (abeba ya EB-abeban FE), unong ed inkauksoy da. d Enerhiya na inkaporma na depekto VI tan LOS na FAPbI3 ed kontrol. e I barrier ed ion migration ed control tan LOS na FAPbI3. f – eskematikon representasyon na iyalis na I ions (orange spheres) tan gLOS FAPbI3 (gray, lead; violet (orange), iodine (mobile iodine)) ed gf control (kawanan: tagey a nengnengen; kawanan: cross section, brown); carbon; light blue – nitrogen; ambalanga – oksihena; light pink – hydrogen). Say source data et niiter ed nengneng na source data files.
Insan mi sistematikon inaral so impluensya na nanduruman intrinsic point defects (kaiba lay PbFA, IFA, PbI, tan IPb antisite occupancy; Pbi tan Ii interstitial atoms; tan VI, VFA, tan VPb vacancies), ya ipapasen ya manunan sengegan. ya pansengegan na atomic tan energy level phase degradation et nanengneng ed Figure 1b tan Supplementary Table 1. Makapainteres, aliwan amin ya depekto et mamapaabeba ed energy barrier na α-δ phase transition (Figure 1b). Manisia kami ya saray depekto ya walaan na abeban enerhiya na pormasyon tan abeban α-δ phase transition energy barriers et ipapasen ya makaderal ed inkapekder na phase. Unong ed akauna lan nireport, saray tapew ya dakel so lead to et kaslakan ya ipapasen ya epektibo parad formamidine PSC27. Kanian, manpokus kami ed PbI2-terminated (100) ya tapew diad silong na lead-rich ya kondisyon. Say enerhiya na depekto ed saray depekto ed tapew na intrinsic point et nanengneng ed Figure 1c tan Supplementary Table 1. Base ed energy barrier (EB) tan phase transition formation energy (FE), sarayan depekto et naapag ed taloran klase. Type I (low EB-high FE): Anggaman say IPb, VFA tan VPb et makabkabaliksan ya mamapaabeba ed energy barrier ed phase transition, walaan ira na atagey iran enerhiya na formation. Kanian, manisia kami ya sarayan klase na depekto et limitado so epekto to ed saray phase transition lapud matalag iran naporma. Type II (high EB): Lapud inmaligwas so α-δ phase transition energy barrier, saray anti-site defects PbI, IFA tan PbFA et agmakaderal ed phase stability na α-FAPbI3 perovskite. Type III (abeban EB-abeban FE): VI, Ii tan Pbi ya depekto ya walaan na medyo abeban enerhiya na panagporma et nayarin pansengegan na black phase degradation. Lalo la ta say sankaabebaan ya FE tan EB VI, manisia kami ya say sankaepektiboan ya estratehiya et say pambawas ed saray bakante ya I.
Pian nabawasan so VI, nanggawa kami na makapal a layer na PbC2O4 pian napaaligwas so tapew na FAPbI3. No ikompara ed saray organic halide salt passivators a singa say phenylethylammonium iodide (PEAI) tan n-octylammonium iodide (OAI), say PbC2O4, ya anggapoy mobile halogen ions to, et malet ed kemikal, ag natunaw ed danum, tan mainomay ya na-deactivate no na-stimulate. Maong ya pangiletneg na danum ed tapew tan electric field na perovskite. Say solubility na PbC2O4 ed danum et 0.00065 g/L labat, ya mas abeba ni nen say PbSO428. Say mas importante, saray makapal tan pareparehon layer na LOS et nayarin maalwar ya iparaan ed perovskite films ya uusaren so in situ reactions (nengnengen ed leksab). Nanggawa kami na DFT simulations na interfacial bonding ed baetan na FAPbI3 tan PbC2O4 a singa nanengneng ed Supplementary Figure 1. Ipapanengneng na Supplementary Table 2 so enerhiya na depekto kayari na LOS injection. Nalmoan mi ya say LOS et aglabat mamaaligwas ed enerhiya na inkaporma na saray depekto na VI na 0.69-1.53 ​​eV (Figure 1d), noagta mamaaligwas met ed enerhiya na panag-aktibo na I diad migration surface tan exit surface (Figure 1e). Diad unonan yugtan, saray I ions et onalis ed tapew na perovskite, ya mangitilak na VI ions ed lattice position ya walay energy barrier ya 0.61 eV. Kayari na pangiloob na LOS, lapud epekto na steric hindrance, say activation energy parad migration na I ions et ondarakel ed. 1.28 eV. Legan na iyalis na I ions ya ontaynan ed tapew na perovskite, say energy barrier ed VOC et mas atagey met nen say control sample (Fig. 1e). Saray schematic diagrams na I ion migration pathways ed control tan LOS FAPbI3 et nanengneng ed Figure 1 f tan g, unong ed inkauksoy da. Ipapanengneng na resulta na simulation ya say LOS et makaamper ed pakaporma na VI defects tan say volatilization na I, kanian naamper so nucleation na α ya anggad δ phase transition.
Say reaksion na oxalic acid tan FAPbI3 perovskite so sinubok. Kayari na impanlaok na solusyon na oxalic acid tan FAPbI3, dakel so amputin precipitate ya aporma, a singa nanengneng ed Supplementary Figure 2. Say produkto na pulbos et abitla bilang puron PbC2O4 ya materyales ya inusar so X-ray diffraction (XRD) (Supplementary Figure 3) tan Fourier transform infrared spectroscopy (FT) (Supplementary Figure 4). Nalmoan mi ya say oxalic acid et natunaw a maong ed isopropyl alcohol (IPA) diad temperatura na kuarto ya say solubility to et ngalngalin 18 mg/mL, a singa nanengneng ed Supplementary Figure 5. Saya so mamagaan ed ontumbok a panagproseso lapud say IPA, bilang sakey a kaslakan a passivation solvent, et agmakaderal ed perovskite layer ed antikey a panaon. Kanian, diad pangilusob ed perovskite film ed solusyon na oxalic acid odino pangi-spin-coat ed solusyon na oxalic acid ed perovskite, say manipis tan makapal ya PbC2O4 et maples ya naala ed tapew na perovskite film unong ed onggendan ya chemical equation: H2C2O4 + FAPI3 = PbI3 + FAIO Say FAI et nayarin natunaw ed IPA tan naekal legan ya manluluto. Say kapal na LOS et nayarin kontrolen na oras na reaksion tan say konsentrasyon na precursor.
Saray imahen na scanning electron microscopy (SEM) na control tan LOS perovskite films et nanengneng ed Figures 2a,b. Ipapanengneng na resulta ya say morpolohiya na tapew na perovskite et napreserba a maong, tan dakel a pinon partikulo so nideposito ed tapew na bukel, ya nepeg ya mangirerepresenta ed PbC2O4 layer ya aporma na in-situ a reaksion. Say LOS perovskite film et walaan na medyo mas makinis a tapew (Supplementary Figure 6) tan mas baleg so water contact angle to no ikompara ed control film (Supplementary Figure 7). Say high-resolution transverse transmission electron microscopy (HR-TEM) so inusar pian nabirbir so tapew na produkto. No ikompara ed control film (Fig. 2c), sakey a unipormi tan makapal a manipis a layer ya walay kapal to ya manga 10 nm so malinew ya nanengneng ed tapew na LOS perovskite (Fig. 2d). Diad pangusar na high-angle annular dark-field scanning electron microscopy (HAADF-STEM) pian nanengneng so interface na PbC2O4 tan FAPbI3, malinew ya nanengneng so kiwawala na crystalline regions na FAPbI3 tan amorphous regions na PbC2O4 (Supplementary Figure 8). Say komposisyon na tapew na perovskite kayari na oxalic acid treatment et anengneng panamegley na X-ray photoelectron spectroscopy (XPS) ya sukat, a singa nanengneng ed Figures 2e-g. Diad Figure 2e, say C 1s peaks ya manga 284.8 eV tan 288.5 eV et kabiangan na espisipikon CC tan FA signals, unong ed inkauksoy da. No ikompara ed control membrane, say LOS membrane et walay kaaruman ya peak to ed 289.2 eV, ya lapud C2O42-. Say O 1s spectrum na LOS perovskite et walaan na taloran chemically distinct O 1s peaks ed 531.7 eV, 532.5 eV, tan 533.4 eV, ya mipara ed deprotonated COO, C=O na intact oxalate groups 30 tan O atoms na OH component (Fig. 2). )). Parad control sample, melag labat so O 1s peak ya naobserbaan, ya nayarin ipasen ya lapud oxygen ya na-chemisorb ed tapew. Say control membrane characteristics na Pb 4f7/2 tan Pb 4f5/2 et walad 138.4 eV tan 143.3 eV, unong ed inkauksoy da. Naobserbaan mi ya say LOS perovskite et mangipapanengneng na iyalis na Pb peak ya manga 0.15 eV ya mamaarap ed mas atagey ya enerhiya na panag-apiger, ya mangipapanengneng na mas mabiskeg ya pidedeneng na C2O42- tan Pb atoms (Fig. 2g).
a SEM ya imahen na kontrol tan b LOS perovskite films, nengnengen ed tagey. c High-resolution cross-sectional transmission electron microscopy (HR-TEM) na kontrol tan d LOS perovskite films. High-resolution XPS na e C 1s, f O 1s tan g Pb 4f perovskite films. Say source data et niiter ed nengneng na source data files.
Base ed resulta na DFT, diad teorya et naisip ya saray depekto na VI tan say I migration et mainomay ya pansengegan na phase transition manlapud α ya anggad δ. Impanengneng na saray akaunan report ya say I2 et maples ya ompaway ed PC-based perovskite films legan na photoimmersion kayari na pangiparungtal ed saray pelikula ed liwawa tan thermal stress31,32,33. Pian nakumpirma so makapabiskeg ya epekto na lead oxalate ed α-phase na perovskite, inyan mi so control tan LOS perovskite films ed saray transparent ya botelya ya salming ya walay toluene to, insan mi ra in-irradiate na 1 sunlight ed loob na 24 oras. Sinukat mi so pansepsep na ultraviolet tan nanengneng ya liwawa (UV-Vis). ) toluene solution, singa nanengneng ed Figure 3a. No ikompara ed control sample, mas abeba so I2 absorption intensity ya naobserbaan ed kaso na LOS-perovskite, ya mangipapanengneng ya say compact LOS et nayarin mangamper ed pangibulos na I2 manlapud perovskite film legan na light immersion. Saray litrato na aged control tan LOS perovskite films et nanengneng ed saray inset na Figures 3b tan c. Say LOS perovskite et andeket ni, bangta maslak ed control film et nagmaliw ya duyaw. Say UV-visible absorption spectra na immersed film et nanengneng ed Figs. 3b, c. Naobserbaan mi ya say absorption ya mipara ed α ed control film et malinew ya inmabeba. Ginawa so X-ray measurements pian nadokumento so ebolusyon na istruktura na kristal. Kayari na 24 oras ya liwawa, say control perovskite et angipatnag na mabiskeg ya yellow δ-phase signal (11.8°), bangta say LOS perovskite et walaan ni na maong ya black phase (Figure 3d).
Say UV-visible absorption spectra na toluene solutions ya say control film tan LOS film et inyan ed silong na 1 sinag na agew ed loob na 24 oras. Say inset et mangipapanengneng na sakey a vial ya kada pelikula et inyan ed parehon karakel na toluene. b UV-Vis absorption spectra na control film tan c LOS film antis tan kayari na 24 oras ya inyan ed silong na 1 sinag na agew. Say inset et mangipapanengneng na litrato na test film. d X-ray diffraction patterns na control tan LOS films antis tan kayari na 24 oras ya exposure. SEM images na control film e tan film f LOS kayari na 24 oras ya exposure. Say source data et niiter ed nengneng na source data files.
Nanggawa kami na scanning electron microscopy (SEM) ya panagsukat pian nanengneng so pananguman ed microstructural na perovskite film kayari na 24 oras ya liwawa, a singa nanengneng ed Figures 3e,f. Diad control film, saray angkakabaleg a bukel so aderal tan nagmaliw ya angkekelag a dagum, ya mipara ed morpolohiya na δ-phase product FAPbI3 (Fig. 3e). Parad saray LOS films, saray perovskite grains et mansiansian maong so kondisyon da (Figure 3f). Say resulta et akumpirma ya say inkaandi na I et makabkabaliksan ya mamakiwas ed impanguman manlapud andeket a parte ya anggad duyaw a parte, bangta say PbC2O4 so mamapabiskeg ed andeket a parte, ya mangaamper ed pakaandi na I. Lapud say bakante ed tapew et mas atagey nen say grain bulk,34 sayan parte et mas posiblin nagawa ed tapew na ilik. mankakasakey ya mangibubulos na iodine tan manporma na VI. Unong ed impasakbay na DFT, say LOS et makaamper ed pakaporma na saray depekto na VI tan makaamper ed iyalis na I ions ed tapew na perovskite.
Niarum ni, say epekto na PbC2O4 layer ed resistensya na danum na perovskite films ed dagem ed atmospera (relatibon danum ya 30-60%) so inaral. Unong ed nanengneng ed Supplementary Figure 9, say LOS perovskite et andeket ni kayari na 12 ya agew, bangta say control film et nagmaliw ya duyaw. Diad XRD ya sukat, say control film et mangipapanengneng na mabiskeg ya peak ed 11.8° ya mipara ed δ phase na FAPbI3, bangta say LOS perovskite et mansiansian maong so black α phase (Supplementary Figure 10).
Say steady-state photoluminescence (PL) tan time-resolved photoluminescence (TRPL) so inusar pian aralen so passivation effect na lead oxalate ed tapew na perovskite. Diad Fig. Figure 4a et mangipapanengneng ya say LOS film et walaan na indakel na PL intensity. Diad PL mapping image, say inkagrabe na LOS film ed interon lugar ya 10 × 10 μm2 et mas atagey nen say control film (Supplementary Figure 11), ya mangipapanengneng ya say PbC2O4 et pareparehon mamapasiva ed perovskite film. Say bilay na carrier et nadetermina diad pangipasen ed TRPL decay ya walay saksakey ya exponential function (Fig. 4b). Say carrier lifetime na LOS film et 5.2 μs, ya mas andukey nen say control film ya walay carrier lifetime ya 0.9 μs, ya mangipapanengneng na abawasan ya surface nonradiative recombination.
Steady-state PL tan b-spectra na temporaryon PL na perovskite films ed saray glass substrates. c SP curve na device (FTO/TiO2/SnO2/perovskite/spiro-OMeTAD/Au). d EQE spectrum tan Jsc EQE spectrum ya intipon manlapud sankaepektiboan ya kagawaan. d Depende na inkagrabe na liwawa na perovskite device ed Voc diagram. f Tipikal ya panagsukimat na MKRC ya uusaren so ITO/PEDOT:PSS/perovskite/PCBM/Au clean hole device. Say VTFL so sankatageyan ya boltahe na panagpano na trap. Manlapud sarayan datos et kinalkula mi so trap density (Nt). Say source data et niiter ed nengneng na source data files.
Pian naaralan so epekto na lead oxalate layer ed performance na device, inusar so tradisyonal ya FTO/TiO2/SnO2/perovskite/spiro-OMeTAD/Au contact structure. Uusaren mi so formamidine chloride (FACl) bilang additive ed perovskite precursor imbes ya methylamine hydrochloride (MACl) pian mas maong so performance na device, lapud say FACl et makapangiter na mas maong ya kalidad na kristal tan napaliisan so band gap na FAPbI335 (nengnengen so Supplementary Figures 1 tan 2 parad detalyadon panangikompara). ). 12-14). Say IPA so pinili bilang antisolvent lapud mas maong so kalidad na kristal tan mas labay so orientation to ed perovskite films no ikompara ed diethyl ether (DE) odino chlorobenzene (CB)36 (Supplementary Figures 15 tan 16). Say kapal na PbC2O4 et maalwar ya in-optimize pian nabalanse so defect passivation tan charge transport diad pangi-adjust ed konsentrasyon na oxalic acid (Supplementary Figure 17). Saray cross-sectional SEM images na saray optimized control tan LOS devices et nanengneng ed Supplementary Figure 18. Saray tipikal ya current density (CD) curves parad control tan LOS devices et nanengneng ed Figure 4c, tan saray naekal ya parameters et niiter ed Supplementary Table 3. Maximum power conversion efficiency (PCE) controls (34%, 24%, 24% JJ. 25.75 mA cm-2 (25.74 mA cm-2), Voc 1.16 V (1.16 V) tan reverse (forward) scan. Say fill factor (FF) et 78.40% (76.69%). Say sankatageyan ya PCE LOS PSC et 25.39% (24.79%), Jsc et 25.77 mA cm-2, Voc et 1.18 V, FF et 83.50% (81.52%) manlapud reverse (forward Scan to). Say LOS device et akaawat na sertipikadon photovoltaic performance ya 24.92% diad sakey a napanmatalkan ya third-party photovoltaic laboratory (Supplementary Figure 19). Say external quantum efficiency (EQE) so angiter na integrated Jsc ya 24.90 mA cm-2 (kontrol) tan 25.18 mA cm-2 (LOS PSC), ya mipara ed Jsc ya sinukat ed standard AM 1.5 G spectrum (Fig. .4d). ) . Say estadistikal ya inkaapag-apag na saray asukat ya PCEs parad control tan LOS PSCs et nanengneng ed Supplementary Figure 20.
Unong ed nanengneng ed Figure 4e, say siglaotan na Voc tan say inkagrabe na liwawa et kinalkula pian naaralan so epekto na PbC2O4 ed trap-assisted surface recombination. Say slope na fitted line parad LOS device et 1.16 kBT/sq, ya mas abeba nen say slope na fitted line parad control device (1.31 kBT/sq), ya mamaneknek ya say LOS et mausar parad pangisebel ed surface recombination na saray decoy. Uusaren mi so space charge current limiting (SCLC) ya teknolohiya pian nasukat so karakel na depekto na perovskite film diad panukat ed dark IV ya ugali na hole device (ITO/PEDOT:PSS/perovskite/spiro-OMeTAD/Au) a singa nanengneng ed pigura. 4f Ipanengneng. Say densidad na trap et nakalkula ed pormula ya Nt = 2ε0εVTFL/eL2, ya say ε et say relatibon dielectric constant na perovskite film, ε0 et say dielectric constant na vacuum, say VTFL et say limitasyon na boltahe parad panpano na trap, e et say karga, L et say kapal na perovskite film (6 nrom). Say depekto na VOC device et kinalkula ya 1.450 × 1015 cm–3, ya abeba nen say depekto na control device, ya 1.795 × 1015 cm–3.
Say ag-akabalot ya kagawaan et sinubok ed sankatageyan ya power point (MPP) diad silong na liwawa na agew diad silong na nitroheno pian nanengneng so andukey a panaon ya inkapekder na performance to (Figure 5a). Kayari na 550 oras, say LOS device et nansiansia nin siansia na 92% na sankatageyan ya efficiency to, bangbalet say performance na control device et inmabeba ed 60% na orihinal ya performance to. Say inkaapag-apag na saray elemento ed daan ya kagawaan et sinukat panamegley na time-of-flight secondary ion mass spectrometry (ToF-SIMS) (Fig. 5b, c). Say baleg ya akumulasyon na iodine et nanengneng ed tagey ya gold control area. Say kondisyon na proteksion na inert gas et ag to kaiba iray makaderal ed kaliberliber a singa say danum tan oksiheno, ya mangisusuheri ya saray mekanismo ed loob (salanti, say ion migration) so responsable. Base ed resulta na ToF-SIMS, saray I- tan AuI2- ions so anengneng ed Au electrode, ya mangipapanengneng na inkayat na I manlapud perovskite ya amaarap ed Au. Say signal intensity na I- tan AuI2- ions ed control device et ngalngalin 10 beses ya mas atagey nen say VOC sample. Impanengneng na saray akaunan report ya say ion permeation et nayarin pansengegan na maples ya ibawas na hole conductivity na spiro-OMeTAD tan say chemical corrosion na top electrode layer, kanian onkapuy so interfacial contact ed device37,38. Say Au electrode et inekal tan say spiro-OMeTAD layer et linisan manlapud substrate panamegley na chlorobenzene solution. Insan mi in-karakterisa so pelikula ya inusar so grazing incidence X-ray diffraction (GIXRD) (Figure 5d). Ipapanengneng na resulta ya say control film et walay mapatnag ya diffraction peak to ed 11.8°, bangbalet anggapoy balon diffraction peak ya ompatnag ed LOS sample. Ipapanengneng na resulta ya say baleg ya pakaandi na I ions ed control film et mangitonton ed pakawalaan na δ phase, bangbalet diad LOS film et malinew ya naamper iyan proseso.
575 oras na tuloytuloy ya MPP tracking na sakey ya unsealed device ed nitrogen atmosphere tan 1 sunlight ya anggapoy UV filter. ToF-SIMS distribution na b I- tan c AuI2- ions ed LOS MPP control device tan aging device. Say kolor na duyaw, berde tan kahel et mipara ed Au, Spiro-OMeTAD tan perovskite. d GIXRD na perovskite film kayari na MPP test. Say source data et niiter ed nengneng na source data files.
Say temperatura-dependent conductivity et sinukat pian nakumpirma ya say PbC2O4 et makaamper ed ion migration (Supplementary Figure 21). Say activation energy (Ea) na ion migration et nadetermina diad panukat ed pananguman na konduktibidad (σ) na FAPbI3 film ed nanduruman temperatura (T) tan pangusar ed Nernst-Einstein relation: σT = σ0exp(−Ea/kBT), ya say σ0 et sakey a constant, say kB et say Boltnzman constant. Naala tayo so balor na Ea manlapud slope na ln(σT) sumpad 1/T, ya 0.283 eV parad kontrol tan 0.419 eV parad LOS device.
Diad sumaryo, mangiiter kami na teoretikal a balangkas pian naamtaan so dalan na inkagba na FAPbI3 perovskite tan say impluensya na nanduruman depekto ed energy barrier na α-δ phase transition. Diad sarayan depekto, saray depekto na VI et teorya ya ipapasakbay ya mainomay ya pansengegan na phase transition manlapud α ya anggad δ. Say ag-ontunaw ed danum tan malet ed kemikal ya makapal a layer na PbC2O4 so inloob pian napabiskeg so α-phase na FAPbI3 diad pangisebel ed pakaporma na I vacancies tan say iyalis na I ions. Sayan estratehiya so makabkabaliksan a mamawas ed interfacial non-radiative recombination, mamaaligwas ed inkaepektibo na solar cell ya anggad 25.39%, tan mamaaligwas ed operating stability. Saray resulta mi et mangiiter na giya pian nadampot so epektibo tan malet ya formamidine PSCs diad pangisebel ed depekto-induced α to δ phase transition.
Say Titanium(IV) isopropoxide (TTIP, 99.999%) et sinaliw ed Sigma-Aldrich. Say hydrochloric acid (HCl, 35.0-37.0%) tan ethanol (anhydrous) et sinaliw ed Guangzhou Chemical Industry. Say SnO2 (15 wt% tin(IV) oxide colloidal dispersion) et sinaliw ed Alfa Aesar. Say lead(II) iodide (PbI2, 99.99%) et sinaliw ed TCI Shanghai (China). Formamidine iodide (FAI, ≥99.5%), formamidine chloride (FACl, ≥99.5%), methylamine hydrochloride (MACl, ≥99.5%), 2,2′,7,7′-tetrakis-(N , N-di-p) )-methoxyaniline)-spirofluore9′,9′ (Spiro-OMeTAD, ≥99.5%), lithium bis(trifluoromethane)sulfonylimide (Li-TFSI, 99.95%), 4-tert -butylpyridine (tBP, 96%) et sinaliw ed Xi'an Polymer Light Technology Company (China). N,N-dimethylformamide (DMF, 99.8%), dimethyl sulfoxide (DMSO, 99.9%), isopropyl alcohol (IPA, 99.8%), chlorobenzene (CB, 99.8%), acetonitrile (ACN). Sinaliw ed Sigma-Aldrich. Say oxalic acid (H2C2O4, 99.9%) et sinaliw ed Macklin. Amin ya kemikal et inusar unong ed naawat ya anggapoy arum ya pananguman.
Saray ITO o FTO substrates (1.5 × 1.5 cm2) et inlinisan na detergent, acetone, tan ethanol ed loob na 10 min, insan pinamaga ed silong na nitrogen stream. Say makapal a TiO2 barrier layer so inyan ed FTO substrate ya inusar so solusyon na titanium diisopropoxybis(acetylacetonate) ed ethanol (1/25, v/v) ya inyan ed 500 °C ed loob na 60 min. Say SnO2 colloidal dispersion et inlaok ed deionized water diad volume ratio ya 1:5. Diad malinis ya substrate ya inikdan na UV ozone ed loob na 20 minutos, sakey a manipis a pelikula na SnO2 nanoparticles so indeposito ed 4000 rpm ed loob na 30 segundo insan pinainit ed 150 °C ed loob na 30 minutos. Parad perovskite precursor solution, 275.2 mg FAI, 737.6 mg PbI2 tan FACl (20 mol%) so tinunaw ed DMF/DMSO (15/1) ya nanlaok ya solvent. Say perovskite layer et imparaan diad panamegley na pan-centrifuge na 40 μL na perovskite precursor solution ed tapew na UV-ozone-treated SnO2 layer ed 5000 rpm diad dagem ed loob na 25 s. 5 segundo kayari na unor ya pankanawnawa, 50 μL na MACl IPA solution (4 mg/mL) so maples ya inpelag ed substrate bilang antisolvent. Insan, saray balon akaparaan ya pelikula et in-anneal ed 150°C ed loob na 20 min insan ed 100°C ed loob na 10 min. Kayari na impamalemew ed perovskite film ed temperatura na kuarto, say solusyon na H2C2O4 (1, 2, 4 mg ya tinunaw ed 1 mL IPA) et in-centrifuge ed 4000 rpm ed loob na 30 s pian na-passive so tapew na perovskite. Say spiro-OMeTAD ya solusyon ya imparaan diad impanlaok na 72.3 mg spiro-OMeTAD, 1 ml CB, 27 μl tBP tan 17.5 μl Li-TFSI (520 mg ed 1 ml ya acetonitrile) et in-spin-coat ed pelikula ed 4000 rpm ed loob na 300 s. Diad kaunoran, say 100 nm ya kapal na Au layer so in-evaporate ed vacuum diad kapeles ya 0.05 nm/s (0~1 nm), 0.1 nm/s (2~15 nm) tan 0.5 nm/s (16~100 nm) . ).
Say SC performance na perovskite solar cells et sinukat ya inusar so Keithley 2400 meter ed silong na solar simulator illumination (SS-X50) diad light intensity ya 100 mW/cm2 tan na-verify ya inusar so calibrated standard silicon solar cells. Likud no walay arum ya nibaga, saray kurba na SP et sinukat ed glove box ya napnoy nitrogen diad temperatura na kuarto (~25°C) diad forward tan reverse scan modes (voltage step 20 mV, delay time 10 ms). Say shadow mask so inusar pian naamtaan so epektibon area ya 0.067 cm2 parad sinukat ya PSC. Saray sukat na EQE et ginawa ed kaliberliber ya dagem ya inusar so PVE300-IVT210 system (Industrial Vision Technology(s) Pte Ltd) ya walay monochromatic light ya akasentro ed device. Parad inkapekder na kagawaan, say panagsukimat ed saray solar cell ya anggapoy encapsulate et ginawa ed nitrogen glovebox ed 100 mW/cm2 ya presyon ya anggapoy UV filter. Say ToF-SIMS et nasukat ya uusaren so PHI nanoTOFII time-of-flight SIMS. Say depth profiling et naala ya inusar so 4 kV Ar ion gun ya walay kalawakan ton fi400×400 μm.
Say X-ray photoelectron spectroscopy (XPS) ya sukat et ginawa ed Thermo-VG Scientific system (ESCALAB 250) ya inusar so monochromatized Al Kα (parad XPS mode) ed pressure ya 5.0 × 10–7 Pa. Say scanning electron microscopy (SEM) et ginawa ed JESM-JOL-3030 F system. Say morpolohiya na tapew tan inka-magaspang na perovskite films et sinukat ya inusar so atomic force microscopy (AFM) (Bruker Dimension FastScan). Say STEM tan HAADF-STEM et nagagawa ed FEI Titan Themis STEM. Say UV-Vis absorption spectra et sinukat ya inusar so UV-3600Plus (Shimadzu Corporation). Say space charge limiting current (SCLC) et nirekord ed Keithley 2400 meter. Say steady-state photoluminescence (PL) tan time-resolved photoluminescence (TRPL) na carrier lifetime decay et sinukat ya inusar so FLS 1000 photoluminescence spectrometer. Saray imahen na PL mapping et sinukat ya inusar so Horiba LabRam Raman system HR Evolution. Say Fourier transform infrared spectroscopy (FTIR) et ginawa ya inusar so Thermo-Fisher Nicolet NXR 9650 system.
Diad sayan kimey, inusar mi so SSW path sampling method pian aralen so phase transition path manlapud α-phase ya anggad δ-phase. Diad SSW ya paraan, say galaw na potensyal ya enerhiya et nadetermina ed direksion na random soft mode (komaduan derivative), ya mangiter na detalyado tan obhetibo ya panaral ed potensyal ya enerhiyan tapew. Diad sayan kimey, say path sampling et gagawaen ed 72-atom supercell, tan masulok ya 100 ya initial/final state (IS/FS) pairs so nakolekta ed DFT level. Base ed IS/FS pairwise data set, say dalan ya mangikokonekta ed inmunan istruktura tan say sampot ya istruktura et nayarin nadetermina ed pantutunosan na saray atomo, insan say duaran dalan ya galaw ed variable unit surface et nausar pian nadetermina so paraan na transition state. (VK-DESV). Kayari na pananap ed estado na pananguman, say dalan ya walaan na sankaabebaan ya babeng et nayarin nadetermina diad pangiranggo ed saray babeng na enerhiya.
Amin ya kalkulasyon na DFT et ginawa ya inusar so VASP (version 5.3.5), ya ditan et say electron-ion ya interaksion na C, N, H, Pb, tan I ya atomo et nirepresenta na projected amplified wave (PAW) scheme. Say exchange correlation function et adeskribe ed generalized gradient approximation diad Perdue-Burke-Ernzerhoff parametrization. Say limitasyon na enerhiya parad plane waves et inletneg ed 400 eV. Say Monkhorst-Pack k-point grid et walay kabaleg ton (2 × 2 × 1). Parad amin ya istruktura, say posisyon na lattice tan atomo et sigpot ya na-optimize anggad say sankatageyan ya stress component et abeba nen 0.1 GPa tan say sankatageyan ya force component et abeba nen 0.02 eV/Å. Diad modelo na tapew, say tapew na FAPbI3 et walaan na 4 a layer, say leksab a layer et walaan na saray akapeket ya atomo ya singa laman na FAPbI3, tan say taloran tagey a layer et nayarin onkiwas a bulos legan na proseso na panag-optimize. Say PbC2O4 layer et 1 ML so kapal to tan walad I-terminal ya tapew na FAPbI3, ya ditan et akapeket so Pb ed 1 I tan 4 O.
Parad kaaruman ya impormasyon nipaakar ed desinyo na panagaral, nengnengen so Natural Portfolio Report Abstract ya asosasyon na sayan artikulo.
Amin ya datos ya naala o naanalisa legan na sayan impanaral et inlaktip ed nipalapag ya artikulo, ontan met ed saray onsusuportan impormasyon tan raw data files. Say raw data ya nipresenta ed sayan impanaral et naromog ed https://doi.org/10.6084/m9.figshare.2410016440. Say nanlapuan na datos et niiter parad sayan artikulo.
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