Homogeneously Alloyed CdSe1-xSx Quantum Dots (0 ≤ x ≤ 1)

Homogeneously Alloyed CdSe1-xSxQuantum Dots (0 ≤x≤ 1)
TangiAubert, MarcoCirillo,StijnFlamee,RikVanDeun,HolgerLange,Christian Thomsen,ZegerHens
E-MRS Spring Meeting 2013, Strasbourg, France
TuningopticalpropertiesofQDs
sizedependent
compositiondependent
alloyedQDs
AlloyedQDs
Baileyet al.,J. Am.Chem. Soc.2003,125, 7100;Swafford et al.J. Am. Chem. Soc.2006,128,12299;Gurusingheet al.J. Phys. Chem. C2008,112,12795;Zhenget al.Adv. Mater.2007,19,1475.
II-VIalloys: Cd(Se,Te), Cd(Se,S), Cd(Te,S), (Cd,Zn)Se, …
gradient
homogeneous
core-shell
HeterogeneousSe-ODEsynthesis
S.Flamee, M.Cirillo, S. Abe, K. DeNolf, R. Gomes, T.Aubert, Z.Hens,submitted.S.Flamee,R.Dierick, M.Cirillo, D.VanGenechten, T.Aubert, Z.Hens,Dalton Trans.2013.doi10.1039/c3dt50757bS.Flamee, Z. Hens, patent n°PCT/EP2012/072428,2012.
SynthesisofCdSe,ZnSe,CuInSe2andCu2(Zn,Sn)Se4QDs
heterogeneousSe-ODE
TC
ODEcarboxylicacidCdO
- open air (no flushing)- T = 260°C- 5 min reaction- nearly full yield- high solid load
allowlargeproduction
HeterogeneousSe-ODEsynthesis
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
HeterogeneousSe-ODE vs.HomogeneousS-ODE
heterogeneousSe-ODE
homogeneousS-ODE
OR
equivalentreactivitiestowards Cd
CdSe
CdS
CdSe1-xSxsynthesis
Tunablesynthesisthroughentirecompositionrange (0 ≤x≤ 1)
heterogeneousSe-ODE
homogeneousS-ODE
AND
1-x
x
CdSe1-xSx
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
CdSe1-xSxalloyedQDs
Morphologyandstructure(TEM)
sizecanstillbetunedwithacidlength
CdSe0.5S0.5size= 3nm(myristic acid)
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
CdSe1-xSxalloyedQDs
Morphologyandstructure(XRD)
latticeparameterfollowsVegard’slaw
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
CdSe1-xSxalloyedQDs
Morphologyandstructure(Raman)
- LOshiftswithcomposition-narrowFWHMforx= 0, 0.5and1- large FWHMforunevencompositions
fittedLO bands
LOfrequencyandFWHM
homogeneous alloying
CdSe1-xSxalloyedQDs
Opticalproperties
absorption
emission
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
CdSe1-xSx/CdScore-shellQDs
Li et al., J. Am.Chem. Soc.2003,125, 12567.
Synthesis:layer-by-layer(SILAR)
→ PL enhancement decreases with increasing S content in the core
CdSe1-xSx/CdScore-shellQDs
Confinement energy:Econf(CdSe1-xSx/CdS) =Eg(CdSe1-xSx/CdS) -Eg,∞(CdSe1-xSx)Eg,∞(CdSe1-xSx) = (1-x)Eg(CdSe) +xEg(CdS) -bx(1-x)
T.Aubert, M.Cirillo, S.Flamee, R. Van Deun, H. Lange, C.Thomsen, Z.Hens,Chem. Mater.,10.1021/cm401019t
Conclusion
CdSe1-xSxalloyed QDs- fast, high yield and tunable synthesis- homogeneous alloying (Raman spectroscopy)- efficient tuning of the band gap
just accepted in Chemistry of Materials, DOI:10.1021/cm401019t
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Aknowledgement
Thanks for your attention !
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