iron pyrite (fes2lawm/law 10-14-10.pdf · 2010. 12. 12. · pyrite (fes 2) cubic, e g = 0.95 ev...
TRANSCRIPT
![Page 1: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/1.jpg)
Iron Pyrite (FeS2)Iron Pyrite (FeS2)
Fool’s gold ElectronicCrystal structure
Electronic structure
• suitable bandgap (0.95 eV)• very strong light absorption• adequate diffusion lengths • extremely cheap• infinitely abundant
P it t h t li t f thi fil t i l bl f
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu1
Pyrite tops a short list of thin film materials capable of scaling to multiple TWs without resource limitations
![Page 2: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/2.jpg)
Pyrite suffers from a low voltagePyrite suffers from a low voltage
Pyrite tends to be sulfur deficient, and sulfur defects create states in the bandgap, limiting the voltageg p, g g
Performance: 40 mA cm-2 , < 0.2 V, 3.3%
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu2Passivating surface defects is the key to boosting cell efficiency
![Page 3: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/3.jpg)
Pyrite growth updatePyrite growth update
Our goal: Powerpoint Perfect Pyrite g p y
pyrite film
substratesubstrate
• uniform dense pinhole free uniform, dense, pinhole free • largest possible grains• tunable thickness (50–2000 nm)
fl t• flat• stoichiometric • scalable processing
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu3
p g• substrate independent
![Page 4: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/4.jpg)
Team PyriteTeam Pyrite
Nick – CVD James – nanocrystal inks Sean – NC & molecular inks
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu44
Amanda – molecular inksKrys – CdS CBD Yinglei – ZnS CBD
![Page 5: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/5.jpg)
Pyrite growth capabilitiesPyrite growth capabilities
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu5
![Page 6: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/6.jpg)
Chemical vapor deposition (CVD) routeChemical vapor deposition (CVD) route
300°Cglass
pyrite thin film
Fe(acac)3 (solid) TBDS (liquid)
+300°CAr flow
othermarcasite + pyrite
( )3 ( ) TBDS (liquid)substrate
Films are annealed in S2 to convert marcasite to pyrite and improve grain structure.
on glass (pure pyrite) 500°C S2 annealed (pure pyrite)
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu6
![Page 7: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/7.jpg)
on glass (pure pyrite) 500°C S2 annealed (pure pyrite)g (p py ) 2 (p py )
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu7
![Page 8: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/8.jpg)
on silicon (marcasite/pyrite) 650°C S2 annealed (pure pyrite)
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu8
![Page 9: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/9.jpg)
Nanocrystal approach (James, Sean)Nanocrystal approach (James, Sean)
Nanocrystali k
100 nm
ink
Synthesize NCs Dip coat to make NC film
Sinter in sulfur
Procedure• FeCl2 + sulfur in octadecylamine at 220°C.
Li d h d l h i
y D p coat to make NC f lm
• Ligand exchange to octadecylxanthate to improve solubility.
Dip coating in glove box (up to 3 um thick) from 100
‐
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu9
• Dip coating in glove box (up to 3 um thick) from NCs in chloroform and 1 M hydrazine in CH3CN
• Final anneal at 500-600°C in sulfur-filled ampoule.
100 nm
![Page 10: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/10.jpg)
Pyrite nanocrystals: A challengePyrite nanocrystals: A challenge
Early results: aggregates• multiple Fe-S phases• difficult to crystallize• tends to aggregatetends to aggregate
I lfid hPyrite (FeS2) cubic, Eg = 0.95 eV (indirect; 1.01 eV direct gap)
diamagnetic semiconductor (Van Vleck paramagnet) M it (F S ) th h bi E 0 4 V (i di t)
Iron sulfide phases
Marcasite (FeS2) orthorhombic, Eg = 0.4 eV (indirect) diamagnetic semiconductor
Greigite (Fe3S4) cubic, Eg = 0.4 eV, ferrimagneticPyrrhotite hexagonal or monoclinic E ≈ 0 2 eV
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu10
Pyrrhotite(Fe1-xS, with x ≤ 0.2)
hexagonal or monoclinic, Eg ≈ 0.2 eV diamagnetic or ferromagnetic semiconductor
Troilite (FeS) hexagonal, Eg = 0.04 eV, antiferromagnetic semiconductor
![Page 11: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/11.jpg)
Pyrite nanocrystal inksPyrite nanocrystal inks
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu11
![Page 12: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/12.jpg)
Reaction progression
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu
![Page 13: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/13.jpg)
Film formation
• temperaturetime
Grain growth depends on:
• time• heating/cooling rates• substrate
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu13
• amount of sulfur
![Page 14: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/14.jpg)
On glass
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu14
![Page 15: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/15.jpg)
On potential device substrates
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu15
![Page 16: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/16.jpg)
Molecular ink approachesMolecular ink approaches
F SFe S
cast & cook
DMSOethanolamineMolecular
ink
• simple and scalablelow/no impurities• low/no impurities
• tunable composition• easy doping/alloying
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu16
• low toxicity
![Page 17: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/17.jpg)
Molecular ink approach #1Molecular ink approach #1
1. Fe(acac)3 route (Sean)P dProcedure• 0.8 M Fe(acac)3 + 1.2 M sulfur in pyridine.• Spin coat 200 nm layers, with 350°C bake in between each layer.• Final anneal at ~550°C in sulfur filled ampoule• Final anneal at ~550 C in sulfur-filled ampoule.
Progress• single-anneal films show unconnected grainssingle anneal films show unconnected grains• “2 + 2” process gives moderately dense, medium grain films (rough top layer)
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu17
![Page 18: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/18.jpg)
On glass substratesOn glass substrates
2 layers, 1 sinter step2 x 2
2 22 x 2
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu18
![Page 19: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/19.jpg)
On quartz substratesOn quartz substrates
“2 2”“2 + 2” process350°C bakes in air650°C S anneal650 C S2 anneal
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu19
![Page 20: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/20.jpg)
Growth on FTOGrowth on FTO
h l S S l t f F S Ohttp://cfse.uci.ps.eduhttp://cfse.uci.ps.edu20
hexagonal SnS2 plates form on F:SnO2
![Page 21: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/21.jpg)
Molecular ink approach #2Molecular ink approach #2
2. Iron route (Amanda)Procedure• Fe + sulfur in DMSO/ethanolamine.• Spin coat ~150 nm layers, with 200°C bake in between each layer.• Final anneal at 400-600°C in sulfur-filled ampoule.
Progress• 7 layer films give nicely connected grains
on glass (but rough surface)on glass (but rough surface)• >8 layers?• “7 + 2” process?
on glass:
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu21
![Page 22: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/22.jpg)
Iron route on glassIron route on glass
sodium incorporationsodium incorporation almost a certainty (SIMS)
l f di i
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu22
role of sodium in microstructure?
![Page 23: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/23.jpg)
glass vs. quartz glass vs. quartz
role of sodium in microstructure?
glass:
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu23
![Page 24: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/24.jpg)
probably ~2 um thick
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu24
![Page 25: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/25.jpg)
First H2S sintering results First H2S sintering results
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu25
![Page 26: Iron Pyrite (FeS2lawm/Law 10-14-10.pdf · 2010. 12. 12. · Pyrite (FeS 2) cubic, E g = 0.95 eV (indirect; 1.01 eV direct gap) diamagnetic semiconductor (Van Vleck paramagnet) Mit(F](https://reader036.vdocuments.us/reader036/viewer/2022070208/60f97cca4d696e28a601864b/html5/thumbnails/26.jpg)
ConclusionsConclusions
• CVD gives nice pyrite films (annealing needed on non-glass substrates). Slow growthrate. Films now being used for XPS. Mobilities appear too small for Hall measurements.
• We have stable pyrite nanocrystal inks and pyrite films from same. Sintered films haveWe have stable pyrite nanocrystal inks and pyrite films from same. Sintered films havelarge grain size but usually disconnected grains and rough surfaces. Reproducibility is a nagging problem.
• Fe-acac molecular route gives moderately connected, medium grain films with rough surfaces. Multiple spin/sinter steps results in layered films. Carbon deposition duringsintering may be hindering grain growthsintering may be hindering grain growth.
• Iron molecular route gives best morphology so far with most promising stoichiometry• Iron molecular route gives best morphology so far, with most promising stoichiometry. Large (500-1000 nm), well connected grains. Process is reproducible. Substrate effects are apparent. Films are rough. H2S sintering gives smoother films @ 100-300 nm grain size.
http://cfse.uci.ps.eduhttp://cfse.uci.ps.edu26