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Ing defect passivation maralas yang gagamitan para asundu ing performance da reng lead triiodide perovskite solar cells, pero ing epektu da reng miyayaliwang defect keng α-phase stability e pa malino; keni, gamit ing density functional theory, akilala mi keng mumunang besis ing degradation pathway ning formamidine lead triiodide perovskite manibat α-phase papunta δ-phase ampo abalu mi ing epektu da reng miyayaliwang depektu keng phase transition energy barrier. Ing resulta ning simulation sasabyan na ing iodine vacancies mas maralas yang maging sangkan ning pangasira uling mas mababa ing energy barrier para keng α-δ phase transition ampo atin yang pekamalating formation energy keng perovskite surface. Ing pamaglub ning metung a makapal a layer ning water-insoluble lead oxalate keng perovskite surface makabaldugan yang makapigil keng decomposition ning α-phase, makapigil keng pamag migrate ampo volatilization ning iodine. Dagdag pa, ing diskarting ini makabaldugan yang makabawas king interfacial nonradiative recombination at daragdagan na ing solar cell efficiency angga king 25.39% (certified 24.92%). Ing e makabalut a device malyari ya pa muring panatilyan ing orihinal nang 92% a efficiency kaybat nang me-operate king maximum a sikanan kilub ning 550 oras lalam ning simulated 1.5 G air mass irradiation.
Ing power conversion efficiency (PCE) da reng perovskite solar cells (PSCs) miras na keng certified record high a 26%1. Manibat 2015, deng modernung PSC mas buri da ing formamidine triiodide perovskite (FAPbI3) bilang light-absorbing layer pauli ning kayang masanting a thermal stability ampo ing kayang bandgap malapit keng Shockley-Keisser limit a 2,3,4. Ing makalungkut, deng FAPbI3 films thermodynamically dumalan lang phase transition ibat keng black α phase papunta keng yellow non-perovskite δ phase keng room temperature5,6. Para aiwasan ing pamaglalang ning delta phase, miyayaliwang komplikadung perovskite compositions ing mebuu. Ing peka karaniwan a diskarti para alampasan ing problemang ayni yapin ing pamisanmetung ning FAPbI3 keng methyl ammonium (MA+), cesium (Cs+) ampo bromide (Br-) ions7,8,9. Makanyan man, deng hybrid perovskites magdusa la keng bandgap broadening ampo photoinduced phase separation, na makakompromiso keng performance ampo operational stability da reng PSCs10,11,12.
Deng bayung pamagaral pepakit da na ing purong single crystal FAPbI3 a alang nanu mang doping atin yang masanting a katatagan pauli ning kayang masanting a crystallinity ampo mababang depektu13,14. Uli na niti, ing pamagbawas kareng depektu kapamilatan ning pamagdake king crystallinity ning bulk FAPbI3 metung yang importanting diskarti para akwa ing epektibo at matatag a PSCs2,15. Makanyan man, kabang mag-operate ya ing FAPbI3 PSC, ing pamag-degradate king e mayap a yellow hexagonal non-perovskite δ phase malyari ya pa mu rin16. Ing prosesu keraklan magumpisa ya kareng babo ampo kareng angganan ning butil na mas madaling tanggapan ning danum, pali ampo sala pauli ning presensya da reng dakal a depektibung lugal17. Uli na niti, ing surface/grain passivation kailangan ya para a-stabilize ing black phase ning FAPbI318. Dakal a defect passivation strategies, kayabe na ing pamaglub da reng low-dimensional perovskites, acid-base Lewis molecules, ampo ammonium halide salts, ing mika maragul a progresu keng formamidine PSCs19,20,21,22. Angga ngeni, halus ding sablang pamagaral makatutuk la keng papil da reng miyayaliwang depektu keng pamagdetermina kareng optoelectronic properties antimo ing carrier recombination, diffusion length ampo ing band structure kareng solar cells22,23,24. Alimbawa, ing density functional theory (DFT) magagamit ya para abalu ing formation energies ampo ing trapping energy levels da reng miyayaliwang depektu, na maralas magagamit para mag guide keng practical passivation design20,25,26. Kabang bababa ing bilang da reng depektu, ing katatagan ning kasangkapan keraklan mas masanting ya. Makanyan man, keng formamidine PSCs, ing mekanismo ning impluwensya da reng miyayaliwang depektu keng phase stability ampo ing photoelectric properties dapat maging ganap yang miyayaliwa. Agpang keng kekaming beluan, ing pundasyunal a pamanintindi nung makananu lang mag-induce deng depektu keng cubic to hexagonal (α-δ) phase transition ampo ing papil ning surface passivation keng phase stability ning α-FAPbI3 perovskite e pa masyadung aintindian.
keni, papakit mi ing degradation pathway ning FAPbI3 perovskite manibat keng black α-phase papunta keng yellow δ-phase ampo ing impluwensya da reng miyayaliwang depektu keng energy barrier ning α-to-δ-phase transition kapamilatan ning DFT. I vacancies, na madaling gawan kabang gagawang pelikula ampo ing device operasyun, ila reng peka-malagwang magumpisa keng α-δ phase transition. Uli na niti, pepalub mi ing metung a water-insoluble ampo chemically stable a makapal a layer ning lead oxalate (PbC2O4) babo ning FAPbI3 kapamilatan ning metung a in situ a reaksyun. Ing lead oxalate surface (LOS) babawal ne ing pamaglalang da reng I vacancies ampo pipigilan na ing pamaglipat da reng I ions nung stimuladu ne ning pali, sala, ampo electric fields. Ing resulta ning LOS makabaldugan yang makabawas keng interfacial nonradiative recombination ampo mas masanting ya ing FAPbI3 PSC efficiency keng 25.39% (certified keng 24.92%). Ing unpackaged LOS device menatili yang 92% ning kayang orihinal a efficiency kaybat nang me-operate keng maximum power point (MPP) kilub ning maigit 550 oras keng simulated air mass (AM) a 1.5 G ning radiation.
Mumuna ming gewa ing ab initio a kalkulasyun para akit ing dalan ning pangasira ning FAPbI3 perovskite para keng pamagbayu ibat keng α phase papunta keng δ phase. Kapamilatan ning detalyadung prosesu ning pamagbayu ning phase, ikit da na ing pamagbayu ibat king three-dimensional corner-sharing [PbI6] octahedron king cubic α-phase ning FAPbI3 papunta king one-dimensional edge-sharing [PbI6] octahedron king hexagonal δ-phase ning FAPbI3 meyari ya. breaking 9. Ing Pb-I gagawang bond keng mumunang step (Int-1), at ing kayang energy barrier miraras yang 0.62 eV/cell, antimo ing akakit keng Figure 1a. Nung ing octahedron mipalitan ya keng [0\(\bar{1}\)1] a direksyun, ing hexagonal short chain mipalapad ya manibat 1×1 angga 1×3, 1×4 at katataulian lungub ya keng δ phase. Ing orientation ratio ning mabilug a dalan yapin ing (011)α//(001)δ + [100]α//[100]δ. Manibat keng energy distribution diagram, akit tamu na kaybat ning nucleation ning δ phase ning FAPbI3 kareng tutuking yugtu, ing energy barrier mas mababa ya kesa keng α phase transition, na mangabaldugan na ing phase transition maging mabilis ya. Malino, ing mumunang lakbang ning pamagkontrol king pamagbayu ning phase kritikal ya nung buri tamung pigilan ing α-phase degradation.
a Phase transformation process manibat kayli papunta wanan – black FAPbI3 phase (α-phase), mumunang Pb-I bond cleavage (Int-1) ampo ing karagdagang Pb-I bond cleavage (Int-2, Int -3 ampo Int -4) ampo yellow phase FAPbI3 (delta phase). b Energy barriers keng α to δ phase transition ning FAPbI3 base kareng miyayaliwang intrinsic point defects. Ing dotted line papakit ne ing energy barrier ning metung a ideal a kristal (0.62 eV). c Enerhiya ning pamaglalang da reng mumunang puntong depektu keng babo ning lead perovskite. Ing abscissa axis ya ing energy barrier ning α-δ phase transition, at ing ordinate axis ya ing energy ning defect formation. Deng bage a maka-shade keng grey, yellow ampo green ilapin deng type I (low EB-high FE), type II (high FE) ampo type III (low EB-low FE), respectively. d Enerhiya ning pamaglalang da reng depektu VI ampo LOS ning FAPbI3 keng kontrol. e I barrier keng ion migration keng control ampo LOS ning FAPbI3. f – schematic representation ning pamaglipat da reng I ions (orange spheres) ampo gLOS FAPbI3 (gray, lead; violet (orange), iodine (mobile iodine)) keng gf control (kaili: babo view; wanan: cross section, brown); carbon; light blue – nitrogen; pula – oxygen; light pink – hydrogen). Ing source data mibye ya keng porma da reng source data files.
Kaybat, sistematiku ming inaral ing impluwensya da reng miyayaliwang intrinsic point defects (kayabe na ing PbFA, IFA, PbI, ampo IPb antisite occupancy; Pbi ampo Ii interstitial atoms; ampo VI, VFA, ampo VPb vacancies), na tuturing dang susi a sangkan. na magdalang atomic ampo energy level phase degradation mayayakit la keng Figure 1b ampo Supplementary Table 1. Makawili, ali ngan deng depektu babawasan de ing energy barrier ning α-δ phase transition (Figure 1b). Maniwala kami na deng depektu na ating mababang enerhiya ning pamaglalang ampo mababang α-δ phase transition energy barriers tuturing dong makasira keng phase stability. Antimo ing minunang mibalita, deng lead-rich a balat keraklan tuturing dong epektibo para keng formamidine PSC27. Uli na niti, tutukan mi ing PbI2-terminated (100) a babo lalam ning lead-rich a kundisyun. Ing defect formation energy da reng surface intrinsic point defects mayayakit ya keng Figure 1c ampo Supplementary Table 1. Base keng energy barrier (EB) ampo phase transition formation energy (FE), deng defects a reni makaclassify la keng atlung uri. Type I (low EB-high FE): Agyang ing IPb, VFA ampo VPb makabawas la keng energy barrier keng phase transition, atin lang matas a formation energies. Uli na niti, maniwala kami na deng uri da reng depektu atin lang limitadu a epektu keng pamagbayu ning phase uling bihira lang mabuu. Type II (matas a EB): Uling keng mas masanting a α-δ phase transition energy barrier, deng anti-site defects PbI, IFA ampo PbFA e la makasira keng phase stability ning α-FAPbI3 perovskite. Type III (low EB-low FE): VI, Ii ampo Pbi defects na ating mababang formation energies malyari lang maging sangkan ning black phase degradation. lalu na uling ing pekababang FE ampo EB VI, maniwala kami na ing peka epektibung diskarti yapin ing mabawas la reng bakanting I.
Para mabawas ing VI, ginawa kaming makapal a layer ning PbC2O4 para asundu ing babo ning FAPbI3. Nung ikumpara la kareng organic halide salt passivators antimo reng phenylethylammonium iodide (PEAI) ampo n-octylammonium iodide (OAI), ing PbC2O4, na alang mobile halogen ions, matatag ya keng kemikal, e ya matunaw keng danum, ampo madali yang ma-deactivate nung stimulate ya. Masanting a pamag-stabilize ning surface moisture ampo ing electric field ning perovskite. Ing solubility ning PbC2O4 keng danum 0.00065 g/L yamu, na mas mababa pa kesa keng PbSO428. Ing mas importanti, deng makapal ampo pare-pareung layer ning LOS malyari lang isadya keng perovskite films gamit ing in situ reactions (lawen ya ing lalam). Ginawa kaming DFT simulations ning interfacial bonding pilatan ning FAPbI3 ampo PbC2O4 antimo ing akakit mi keng Supplementary Figure 1. Ing Supplementary Table 2 papakit na ing defect formation energy kaybat ning LOS injection. Ikit mi na ing LOS e mu kabud daragdagan na ing formation energy da reng VI defects king 0.69–1.53 eV (Figure 1d), nune daragdagan na naman ing activation energy ning I king migration surface ampo exit surface (Figure 1e). keng mumunang yugtu, ing I ions mag migrate ya keng perovskite surface, at likuan no reng VI ions keng lattice a posisyun a maki energy barrier a 0.61 eV. Kaybat ning pamaglub ning LOS, pauli ning epektu ning steric hindrance, ing activation energy para keng pamaglipat da reng I ions daragul ya. 1.28 eV. Kabang mag migrate la reng I ions a lulual keng perovskite surface, ing energy barrier keng VOC mas matas ya kesa keng control sample (Fig. 1e). Deng schematic diagrams da reng I ion migration pathways keng control ampo LOS FAPbI3 mayayakit la keng Figure 1 f ampo g, respectively. Ing resulta ning simulation papakit na ing LOS malyari yang makapigil keng pamaglalang da reng VI defects ampo ing volatilization ning I, inya pin makapigil ya keng nucleation ning α to δ phase transition.
Ing reaksyun ning oxalic acid ampo ing FAPbI3 perovskite me-test ya. Kaybat dang timpla deng solusyun ning oxalic acid ampo FAPbI3, maragul a dagul ning maputing precipitate ing mebuu, antimo ing akakit keng Supplementary Figure 2. Ing produktung pulbura mekilala ya bilang purung PbC2O4 a materyales gamit ing X-ray diffraction (XRD) (Supplementary Figure 3) ampo Fourier transform infrared spectroscopy (FT) (Supplementary Figure 4). Ikit mi na ing oxalic acid masyadu yang matunaw keng isopropyl alcohol (IPA) keng temperatura ning silid a maki solubility a manga 18 mg/mL, antimo ing akakit keng Supplementary Figure 5. Iti gagawan na ing tutuking pamagprosesu mas mayan uling ing IPA, bilang metung a karaniwan a passivation solvent, e na sisiran ing perovskite layer kilub ning makuyad a panaun. Uli na niti, kapamilatan ning pamaglub king perovskite film king oxalic acid solution o pamag-spin-coating king oxalic acid solution king perovskite, manipis at makapal a PbC2O4 mabilis yang akwa king babo ning perovskite film agpang king makatuking chemical equation: H2C2O4 + FAPI3 = PbI3 + FAIO Ing FAI malyari yang matunaw keng IPA at makanyan yang milako kabang maglutu ya. Ing kapal ning LOS malyari yang makontrol kapamilatan ning oras ning reaksyun ampo ing konsentrasyun ning precursor.
Deng larawan ning scanning electron microscopy (SEM) ning control ampo LOS perovskite films mayayakit la keng Figures 2a,b. Ing resulta papakit na ing perovskite surface morphology mepreserba ya, at dakal a mapinung particle ing midepositu keng grain surface, na dapat magrepresenta keng PbC2O4 layer a mebuu keng in-situ reaction. Ing LOS perovskite film atin yang mas makinis a babo (Supplementary Figure 6) ampo mas maragul ing water contact angle kumpara keng control film (Supplementary Figure 7). Ing high-resolution transverse transmission electron microscopy (HR-TEM) ing ginamit para akilala ing surface layer ning produktu. Nung ikumpara me keng control film (Fig. 2c), metung a pare-parehu at makapal a manipis a layer a maki kapal a manga 10 nm malino yang akakit keng babo ning LOS perovskite (Fig. 2d). Gamit ing high-angle annular dark-field scanning electron microscopy (HAADF-STEM) para asuri ing interface pilatan ning PbC2O4 ampo FAPbI3, ing presensya da reng crystalline a lugal ning FAPbI3 ampo reng amorphous a lugal ning PbC2O4 malino yang akit (Supplementary Figure 8). Ing surface composition ning perovskite kaybat ning oxalic acid treatment mekilala ya kapamilatan ning X-ray photoelectron spectroscopy (XPS) a sukad, antimo ing mayayakit kareng Figures 2e–g. keng Figure 2e, ing C 1s peaks na makapadurut 284.8 eV ampo 288.5 eV kayabe la kareng specific CC ampo FA signals, respectively. Nung ikumpara me keng control membrane, ing LOS membrane pepakit yang karagdagang peak keng 289.2 eV, a makayagpang keng C2O42-. Ing O 1s spectrum ning LOS perovskite magpakit yang atlung chemically distinct O 1s peaks keng 531.7 eV, 532.5 eV, ampo 533.4 eV, a maki kaugnayan keng deprotonated COO, C=O da reng intact oxalate groups 30 ampo O atoms ning OH component (Fig. 2 ). )). Para keng control sample, metung mung malating O 1s peak ing ikit, na malyaring iugne keng oxygen chemisorbed keng babo. Ing control membrane characteristics ning Pb 4f7/2 ampo Pb 4f5/2 atyu la keng 138.4 eV ampo 143.3 eV, agpang kareti. ikit mi na ing LOS perovskite magpakit yang pamagbayu ning Pb peak na mga 0.15 eV papunta keng mas matas a binding energy, a magpakit mas masikan a pamiugnayan da reng C2O42- ampo Pb atoms (Fig. 2g).
a SEM a larawan ning control ampo b LOS perovskite a pelikula, babo. c High-resolution cross-sectional transmission electron microscopy (HR-TEM) ning control ampo d LOS perovskite films. High-resolution XPS ning e C 1s, f O 1s ampo g Pb 4f perovskite films. Ing source data mibye ya keng porma da reng source data files.
Agpang kareng resulta ning DFT, ing theoretically predict na ing VI defects ampo ing I migration madali lang maging sangkan ning phase transition ibat α papunta δ. Deng minunang ulat pepakit da na ing I2 mabilis yang mipalabas ibat kareng PC-based perovskite films kabang mag-photoimmersion kaybat dang mipalabas deng films keng sala ampo thermal stress31,32,33. Para kumpirman ing stabilizing effect ning lead oxalate keng α-phase ning perovskite, linub mi la reng control ampo LOS perovskite films kareng transparent a glass bottles a maki toluene, at kaybat pepa-irradiate mi la keng 1 sunlight kilub ning 24 h. Sukat mi ing pamagsipsip ning ultraviolet ampo ing akakit a sala (UV-Vis). ) toluene solution, antimo ing akakit keng Figure 3a. Nung ikumpara me keng control sample, mas mababa ing I2 absorption intensity keng kasu ning LOS-perovskite, a papakit na ing compact LOS malyari yang makapigil keng pamaglual ning I2 ibat keng perovskite film kabang light immersion. Deng litrato da reng aged control ampo LOS perovskite films makakit la keng insets da reng Figures 3b ampo c. Ing LOS perovskite maitim ya pa, kabang keraklan keng control film meging yellow ya. Ing UV-visible absorption spectra ning makalub a pelikula mayayakit ya keng Figs. 3b, c. ikit mi na ing absorption a maki kaugnayan keng α keng control film malino yang mebaba. Ing X-ray a sukad megawa ya para idokumentu ing pamagbayu ning istruktura ning kristal. Kaybat ning 24 oras a pamag-illuminate, ing control perovskite pepakit yang masikan a yellow δ-phase signal (11.8°), kabang ing LOS perovskite menatili ya pa muring masanting a black phase (Figure 3d).
UV-visible absorption spectra ning toluene solutions nung nukarin ing control film ampo ing LOS film milub la keng 1 aslag ning aldo kilub ning 24 oras. Ing inset papakit ne ing metung a vial nung nukarin ing balang pelikula milub ya keng parehung dagul ning toluene. b UV-Vis absorption spectra ning control film ampo c LOS film bayu ampo kaybat ning 24 h ning pamaglub lalam ning 1 aslag ning aldo. Ing inset papakit ne ing litrato ning test film. d X-ray diffraction patterns ning control ampo LOS films bayu ampo kaybat ning 24 h ning exposure. SEM images ning control film e ampo film f LOS kaybat ning 24 oras a exposure. Ing source data mibye ya keng porma da reng source data files.
Ginawa kaming scanning electron microscopy (SEM) a sukad para akit mi ing microstructural a pamagbayu ning perovskite film kaybat ning 24 oras a pamag-illuminate, antimo ing akakit mi kareng Figures 3e,f. Ing control film, mangaragul a butil mesira la at meging malating karayum, a maki kaugnayan king morphology ning δ-phase product FAPbI3 (Fig. 3e). Para kareng LOS a pelikula, ing perovskite grains manatili yang masanting a kondisyun (Figure 3f). Ing resulta mekumpirma na ing pangawala ning I makabaldugan yang mag-induce keng pamagbayu ibat keng black phase papunta keng yellow phase, kabang ing PbC2O4 papatatag ne ing black phase, a makaiwas keng pangawala ning I. Uling ing vacancy density keng babo mas matas ya kesa keng grain bulk,34 ing phase ayni mas maralas yang malyari keng babo ning grain. sabay-sabay yang magpalwal iodine ampo gagawang VI. Antimo ing sinabi ning DFT, ing LOS malyari yang makapigil keng pamaglalang da reng VI defects ampo makapigil keng pamaglipat da reng I ions papunta keng perovskite surface.
Dagdag pa, ing epektu ning PbC2O4 layer keng moisture resistance da reng perovskite films keng atmospheric air (relative humidity 30-60%) me-aral ya. Antimo ing akakit tamu keng Supplementary Figure 9, ing LOS perovskite maitim ya pa mu rin kaybat ning 12 aldo, kabang ing control film meging yellow ya. keng XRD a sukad, ing control film papakit yang masikan a peak keng 11.8° a maki kaugnayan keng δ phase ning FAPbI3, kabang ing LOS perovskite tatalan ya keng black α phase (Supplementary Figure 10).
Ing steady-state photoluminescence (PL) ampo ing time-resolved photoluminescence (TRPL) ginamit la para abalu ing passivation effect ning lead oxalate keng babo ning perovskite. Ing Fig. Figure 4a papakit na ing LOS film atin yang PL intensity. Ing PL mapping image, ing intensity ning LOS film keng mabilug a area ning fi10 × 10 μm2 mas matas ya kesa keng control film (Supplementary Figure 11), a papakit na ing PbC2O4 pare-pareu yang passivate ing perovskite film. Ing bie ning carrier mayayakit ya kapamilatan ning pamag-approximate king TRPL decay a maki metung a exponential function (Fig. 4b). Ing carrier lifetime ning LOS film 5.2 μs ya, na mas makaba kesa keng control film na atin carrier lifetime a 0.9 μs, a magpakit na mabawas ing surface nonradiative recombination.
Steady-state PL ampo b-spectra ning pansamantalang PL da reng perovskite films keng glass substrates. c SP curve ning device (FTO/TiO2/SnO2/perovskite/spiro-OMeTAD/Au). d EQE spectrum ampo Jsc EQE spectrum a misasanmetung ibat keng peka efficient a device. d Dependence ning light intensity ning perovskite device keng Voc diagram. f Tipikal a MKRC analysis gamit ing ITO/PEDOT:PSS/perovskite/PCBM/Au clean hole device. Ing VTFL ing maximum a trap filling voltage. Manibat kareng data a reni, kinalkula mi ing trap density (Nt). Ing source data mibye ya keng porma da reng source data files.
Para abalu ing epektu ning lead oxalate layer keng performance ning device, ing tradisyunal a FTO/TiO2/SnO2/perovskite/spiro-OMeTAD/Au contact structure ing ginamit. Gagamitan mi ing formamidine chloride (FACl) bilang additive keng perovskite precursor imbes na methylamine hydrochloride (MACl) para mika mas masanting a performance ning device, uling ing FACl malyari yang mamye mas masanting a crystal quality ampo makaiwas keng band gap ning FAPbI335 (lawen ya ing Supplementary Figures 1 ampo 2 para keng detalyadung pamagkumpara). ). 12-14). Ing IPA mepili ya bilang antisolvent uling mamye yang mas masanting a kalidad ning kristal ampo mas masanting a orientation kareng perovskite films kumpara keng diethyl ether (DE) o chlorobenzene (CB)36 (Supplementary Figures 15 and 16). Ing kapal ning PbC2O4 maingat yang me-optimize para maging balanse ing defect passivation ampo ing charge transport kapamilatan ning pamag-adjust keng oxalic acid concentration (Supplementary Figure 17). Deng cross-sectional SEM images da reng optimized control ampo LOS devices mayayakit la keng Supplementary Figure 18. Deng tipikal a current density (CD) curves para kareng control ampo LOS devices mayayakit la keng Figure 4c, ampo ding me-extract a parameters mayayakit la keng 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) ampo reverse (forward) scan. Ing fill factor (FF) 78.40% (76.69%) ya. Ing maximum PCE LOS PSC 25.39% (24.79%), Jsc 25.77 mA cm-2, Voc 1.18 V, FF 83.50% (81.52%) ibat keng reverse (forward Scan to). Ing LOS device mika certified photovoltaic performance yang 24.92% keng metung a trusted third-party photovoltaic laboratory (Supplementary Figure 19). Ing external quantum efficiency (EQE) dininan neng integrated Jsc a 24.90 mA cm-2 (control) ampo 25.18 mA cm-2 (LOS PSC), agpang, na masanting a pamikasundu keng Jsc a mesukad keng standard AM 1.5 G spectrum (Fig. .4d). ) . Ing statistical distribution da reng mesukad a PCEs para kareng control ampo LOS PSCs mayayakit ya keng Supplementary Figure 20.
Antimo ing akakit tamu keng Figure 4e, ing relasyun ning Voc ampo ing light intensity mekwa ya para abalu ing epektu ning PbC2O4 keng trap-assisted surface recombination. Ing slope ning fitted line para keng LOS device 1.16 kBT/sq ya, na mas mababa kesa keng slope ning fitted line para keng control device (1.31 kBT/sq), a magpatutu na ing LOS magamit ya para keng pamag-inhibit keng surface recombination da reng decoys. Gagamitan mi ing space charge current limiting (SCLC) technology para sukatan ing defect density ning perovskite film kapamilatan ning pamanuknang keng dark IV characteristic ning hole device (ITO/PEDOT:PSS/perovskite/spiro-OMeTAD/Au) antimo ing akakit keng figure. 4f Pakit. Ing trap density makalkula ya keng formula Nt = 2ε0εVTFL/eL2, nung nukarin ε ing relatibong dielectric constant ning perovskite film, ε0 ing dielectric constant ning vacuum, VTFL ing limiting voltage para keng pamagpuno keng trap, e ya ing charge, L ya ing kapal ning perovskite film (605 nrom). Ing defect density ning VOC device mekwa yang 1.450 × 1015 cm–3, na mas mababa kesa keng defect density ning control device, na 1.795 × 1015 cm–3.
Ing unpackaged a device me-test ya keng maximum power point (MPP) lalam ning aldo lalam ning nitrogen para asuri ing kayang long-term performance stability (Figure 5a). Kaybat ning 550 oras, ing LOS device menatili ya pa mu rin 92% ning kayang maximum a kahusayan, kabang ing performance ning control device mibaba ya keng 60% ning kayang orihinal a performance. Ing pamikalat da reng elementu keng lumang device mesukad ya kapamilatan ning time-of-flight secondary ion mass spectrometry (ToF-SIMS) (Fig. 5b, c). Ing maragul a pamitipun ning iodine mayayakit ya keng babo ning gold control area. Deng kundisyun ning proteksyun ning inert gas e la kayabe deng makasira keng kapaligiran antimo ing danum ampo ing oxygen, a magsuggest na deng internal a mekanismo (ie, ion migration) ila reng maki pakibatan. Agpang kareng resulta ning ToF-SIMS, I- ampo AuI2- ions meyakit la keng Au electrode, a magpakit keng diffusion ning I ibat keng perovskite papunta keng Au. Ing signal intensity da reng I- ampo AuI2- ions keng control device manga 10 besis yang mas matas kesa keng VOC sample. Deng minunang ulat pepakit da na ing ion permeation malyari yang magdalang mabilis a pamagbawas keng hole conductivity ning spiro-OMeTAD ampo ing chemical corrosion ning babo ning electrode layer, inya sa’t masira ing interfacial contact keng device37,38. Ing Au electrode mewala ya at ing spiro-OMeTAD layer melinis ya keng substrate gamit ing chlorobenzene solution. Kaybat, linawe mi ing pelikula gamit ing grazing incidence X-ray diffraction (GIXRD) (Figure 5d). Ing resulta papakit na ing control film atin yang malino diffraction peak keng 11.8°, kabang alang bayung diffraction peak a linwal keng LOS sample. Ing resulta papakit na ing maragul a pangawala da reng I ions keng control film magdalang pamaglalang ning δ phase, kabang keng LOS film malino yang makabawal ing prosesung ayni.
575 oras ning patuloy a MPP tracking ning metung a unsealed device keng nitrogen atmosphere ampo 1 sunlight a alang UV filter. ToF-SIMS distribution ning b I- ampo c AuI2- ions keng LOS MPP control device ampo aging device. Deng kule dilaw, berdi ampo orange makayagpang la keng Au, Spiro-OMeTAD ampo perovskite. d GIXRD ning perovskite film kaybat ning MPP test. Ing source data mibye ya keng porma da reng source data files.
Ing temperature-dependent conductivity mesukad ya para kumpirman na ing PbC2O4 malyari yang makapigil keng pamaglipat ning ion (Supplementary Figure 21). Ing activation energy (Ea) ning ion migration abalu ya kapamilatan ning pamanuknang keng pamagbayu keng conductivity (σ) ning FAPbI3 film kareng miyayaliwang temperatura (T) ampo gamit ing Nernst-Einstein relation: σT = σ0exp(−Ea/kBT), nung nukarin ing σ0 metung yang constant, ing kB ing Boltzman constant. Akwa mi ing ulaga ning Ea ibat keng slope ning ln(σT) laban keng 1/T, na 0.283 eV para keng control ampo 0.419 eV para keng LOS device.
keng pamamutut, mamye kaming theoretical framework para akilala ing degradation pathway ning FAPbI3 perovskite ampo ing impluwensya da reng miyayaliwang depektu keng energy barrier ning α-δ phase transition. Kareng depektung deni, deng depektung VI theoretically predicted na madali lang maging sangkan ning pamagbayu ning phase ibat α papunta δ. Ing water-insoluble ampo chemically stable a siksik a layer ning PbC2O4 mipakilala ya para i-stabilize ing α-phase ning FAPbI3 kapamilatan ning pamag-inhibit keng pamaglalang da reng I vacancies ampo ing pamaglipat da reng I ions. Ing diskarting ini makabaldugan yang makabawas keng interfacial non-radiative recombination, daragdagan na ing solar cell efficiency angga 25.39%, ampo mas masanting ya ing operating stability. Ing kekaming resulta mamye yang gabay para akwa ing epektibo at matatag a formamidine PSCs kapamilatan ning pamag-inhibit king defect-induced α to δ phase transition.
Titanium(IV) isopropoxide (TTIP, 99.999%) mesali ya keng Sigma-Aldrich. Ing hydrochloric acid (HCl, 35.0–37.0%) ampo ing ethanol (anhydrous) mesali la keng Guangzhou Chemical Industry. SnO2 (15 wt% tin(IV) oxide colloidal dispersion) mesali ya keng Alfa Aesar. Ing lead(II) iodide (PbI2, 99.99%) mesali ya keng 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)-9′-spirofluore (Spiro-OMeTAD, ≥99.5%), lithium bis(trifluoromethane)sulfonylimide (Li-TFSI, 99.95%), 4-tert -butylpyridine (tBP, 96%) mesali la keng 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). mesali ya keng Sigma-Aldrich. Ing oxalic acid (H2C2O4, 99.9%) mesali ya keng Macklin. Deng sablang kemikal ginamit la antimo ing tinggap da alang aliwang pamagbayu.
ITO o FTO substrates (1.5 × 1.5 cm2) melinis la keng ultrasonic gamit ing detergent, acetone, ampo ethanol kilub ning 10 min, at kaybat mepatuyu la lalam ning nitrogen stream. Ing makapal a TiO2 barrier layer mideposit ya keng FTO substrate gamit ing solusyun ning titanium diisopropoxybis(acetylacetonate) keng ethanol (1/25, v/v) a midepositu keng 500 °C kilub ning 60 min. Ing SnO2 colloidal dispersion me dilute ya keng deionized a danum keng volume ratio a 1:5. King malinis a substrate a me-treat keng UV ozone kilub ning 20 minutu, ing manipis a pelikula ning SnO2 nanoparticles midepositu ya keng 4000 rpm kilub ning 30 segundo at kaybat me-preheat ya keng 150 °C kilub ning 30 minutu. Para keng perovskite precursor solution, 275.2 mg FAI, 737.6 mg PbI2 ampo FACl (20 mol%) ing melaso keng DMF/DMSO (15/1) mixed solvent. Ing perovskite layer mesadya ya kapamilatan ning pamag centrifuge 40 μL ning perovskite precursor solution babo ning UV-ozone-treated SnO2 layer keng 5000 rpm keng ambient air kilub ning 25 s. 5 segundo kaybat ning tauling panaun, 50 μL ning MACl IPA solution (4 mg/mL) mabilis yang mibagsak keng substrate bilang antisolvent. Kaybat, deng bayung makasadya a pelikula me-anneal la keng 150°C kilub ning 20 min at kaybat keng 100°C kilub ning 10 min. Kaybat nang melamig ing perovskite film keng room temperature, ing H2C2O4 solution (1, 2, 4 mg a metunaw keng 1 mL IPA) me centrifuge ya keng 4000 rpm kilub ning 30 s para passivate ing perovskite surface. Ing spiro-OMeTAD a solusyun a mesadya kapamilatan ning pamisanmetung ning 72.3 mg spiro-OMeTAD, 1 ml CB, 27 μl tBP ampo 17.5 μl Li-TFSI (520 mg keng 1 ml acetonitrile) me-spin-coated ya keng pelikula keng 4000 rpm kilub ning 300 s. Katataulian, ing 100 nm makapal a Au layer me-evaporate ya keng vacuum keng rate a 0.05 nm/s (0~1 nm), 0.1 nm/s (2~15 nm) ampo 0.5 nm/s (16~100 nm) . ).
Ing SC performance da reng perovskite solar cells mesukad ya gamit ing Keithley 2400 meter lalam ning solar simulator illumination (SS-X50) keng light intensity a 100 mW/cm2 ampo me-verify ya gamit ing calibrated standard silicon solar cells. Nung ali ya makasulat, deng SP curves mesukad la keng nitrogen-filled glove box keng room temperature (~25°C) keng forward ampo reverse scan modes (voltage step 20 mV, delay time 10 ms). Ing shadow mask ginamit ya para abalu ing epektibung area a 0.067 cm2 para keng mesukad a PSC. Ing sukad ning EQE megawa ya keng angin gamit ing PVE300-IVT210 system (Industrial Vision Technology(s) Pte Ltd) a maki monochromatic a sulu a makatutuk keng device. Para keng katatagan ning device, ing pamagsuri kareng e maka-encapsulated a solar cells megawa ya keng nitrogen glovebox keng 100 mW/cm2 a pressure a alang UV filter. Ing ToF-SIMS mesukad ya gamit ing PHI nanoTOFII time-of-flight SIMS. Ing depth profiling mekwa ya gamit ing 4 kV Ar ion gun a maki area a 400×400 μm.
Ing X-ray photoelectron spectroscopy (XPS) a sukad megawa ya keng Thermo-VG Scientific system (ESCALAB 250) gamit ing monochromatized Al Kα (para keng XPS mode) keng pressure a 5.0 × 10–7 Pa. Ing scanning electron microscopy (SEM) megawa ya keng JESM-JOL-6303F system. Ing surface morphology ampo ing roughness da reng perovskite films mesukad la gamit ing atomic force microscopy (AFM) (Bruker Dimension FastScan). Ing STEM ampo ing HAADF-STEM gagawan de keng FEI Titan Themis STEM. Ing UV-Vis absorption spectra mesukad ya gamit ing UV-3600Plus (Shimadzu Corporation). Ing space charge limiting current (SCLC) merecord ya keng Keithley 2400 meter. Ing steady-state photoluminescence (PL) ampo ing time-resolved photoluminescence (TRPL) ning carrier lifetime decay mesukad la gamit ing FLS 1000 photoluminescence spectrometer. Deng PL mapping images mesukad la gamit ing Horiba LabRam Raman system HR Evolution. Ing Fourier transform infrared spectroscopy (FTIR) megawa ya gamit ing Thermo-Fisher Nicolet NXR 9650 system.
Kening obra ayni, gagamitan mi ing SSW path sampling method para abalu mi ing phase transition path manibat α-phase papunta δ-phase. keng SSW a paralan, ing kimut ning potential energy surface makayagpang ya keng direksyun ning random soft mode (kaduang derivative), na magpaintulut keng detalyadu ampo obhetibong pamagaral keng potential energy surface. Kening obra, ing path sampling gagawan de keng 72-atom supercell, at maigit 100 initial/final state (IS/FS) pairs ing mekolekta keng DFT level. Base keng IS/FS pairwise data set, ing dalan a magkonekta keng mumunang istruktura ampo ing tauling istruktura malyari yang abalu keng pamiugnayan da reng atom, at kaybat ing adwang dalan a kimut keng variable unit surface magagamit ya para abalu ing transition state method. (VK-DESV). Kaybat meng panintunan ing transition state, ing dalan a maki pekababang barrier malyari yang abalu kapamilatan ning pamag-rank kareng energy barriers.
Deng eganaganang DFT a kalkulasyun megawa la gamit ing VASP (version 5.3.5), nung nukarin ing electron-ion interactions da reng C, N, H, Pb, ampo I atoms mipalabas la kapamilatan ning metung a projected amplified wave (PAW) scheme. Ing exchange correlation function mipalabas ya keng generalized gradient approximation keng Perdue-Burke-Ernzerhoff parametrization. Ing limit ning enerhiya para kareng alun ning eroplanu mitakda ya keng 400 eV. Ing Monkhorst-Pack k-point grid atin yang sukad a (2 × 2 × 1). Para kareng eganaganang istruktura, ing lattice ampo ing atomic positions me-optimize la anggang ing maximum stress component atyu ya lalam ning 0.1 GPa ampo ing maximum force component lalam ya 0.02 eV/Å. keng surface model, ing babo ning FAPbI3 atin yang 4 a layer, ing lalam a layer atin yang fixed atoms a magsimulate keng katawan ning FAPbI3, ampo deng babo atlung layer malyari lang gumalaw malaya keng prosesu ning pamag-optimize. Ing PbC2O4 layer 1 ML ya kapal at atyu ya keng I-terminal surface ning FAPbI3, nung nukarin ing Pb makagapus ya keng 1 I ampo 4 O.
Para keng karagdagang impormasyun tungkul keng disenyu ning pamagaral, lawan me ing Natural Portfolio Report Abstract a makasuglung kening artikulu.
Deng eganaganang data a mekwa o me-analisa keng pamagaral ayni kayabe la keng mibulalag a artikulu, ampo kareng susuportang impormasyun ampo kareng raw data files. Ing raw data a mipaintulutan kening pamagaral atyu ya keng https://doi.org/10.6084/m9.figshare.2410016440. Ing penibatan a data makabili ya para keng artikulung ayni.
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