Presentation is loading. Please wait.

Presentation is loading. Please wait.

Semiconducting Polymer Nanoparticles: Spectroscopy and Devices

Similar presentations


Presentation on theme: "Semiconducting Polymer Nanoparticles: Spectroscopy and Devices"— Presentation transcript:

1 Semiconducting Polymer Nanoparticles: Spectroscopy and Devices
T. Kietzke, D. Neher1 R. Güntner, U. Scherf2 R. Montenegro, K. Landfester3 1 Institute of Physics, Univ. Potsdam 2 Institute of Chemistry, Univ. Wuppertal 3 Organic Chemistry III, Univ. Ulm ADMOL 04, Dresden, Germany

2 Nanoparticles and nanoparticle polymer layers
Blends of nanoparticles – nanostructured layers Blend nanoparticles – phase-separation in nanocontainers Some words about photovoltaic devices

3 Nobelprize for Chemistry 2000
for the discovery and development of conductive polymers

4

5 Organic Solar Cells Photogeneration of free charge carriers via photo-induced electron transfer E D A e- h+ - Substrate Donor D Acceptor A Top Electrode (Al) Bottom Electrode ( ITO) = D = A + Bilayer Structure Polymer Blend DA-device structures

6 Polymer Blend Layers Coated from Organic Solvents
PFB F8BT Confocal Raman: PFB-rich PFB:F8BT ca. 50:50 F8BT-rich PFB:F8BT ca. 20:80 PFB:F8BT (1:1) blend spin-cast from xylene R. Stevenson, D. Richards et al. Appl. Phys. Lett. 79 (2001) 2178 J.J.M. Halls, R.H. Friend et al., Adv. Mater. 12 (2000) 498

7 Spincoated Blend Layers
PFB:F8BT layers spincoated from xylene PFB:F8BT 1: : :1 EQE: 4 % % % length scale of phase separation depends on composition H.J. Snaith, R.H. Friend et al., Nanoletters 2 (2002) 1353

8 One Solution! One Solution:
coat layer from emulsion of semiconducting polymer nanoparticles (SPNs) Dimension of phase separation defined by particle diameter But you need to find a way to make nanospheres from polymers T. Kietzke, D. Neher, K. Landfester, U. Scherf et al., Nature Materials, June 2003

9 Nanoparticles and nanoparticle polymer layers
Blends of nanoparticles – nanostructured layers Blend nanoparticles – phase-separation in nanocontainers Some words about photovoltaic devices

10 Alternative Way to Polymer Nanoparticles
water + surfactant polymer solution polymer in organic solvent miniemulsion of polymer solution dispersion of solid polymer particles ultrasound evaporation of solvent The size of the particles can be controlled in the range of nm.

11 Miniemulsions Phase I ultrasound Phase II Polymer Important condition:
polymer + solvent ultrasound Phase II Phase I water and surfactant Important condition: Polymer is completely insoluble in water – can not be transferred between droplets Polymer Solvent molecule Consequence: balance between Laplace pressure and osmotic pressure

12 Semiconducting Polymer Nanoparticles (SPNs)
Tg above decomposition (300 oC) Dispersion under white light Dispersion under UV light (lmax = 365 nm) TEM of nanoparticles Ca. 75 nm diameter K. Landfester, U. Scherf, D. Neher et al., Adv. Mater. 14 (2002) 651

13 AFM of a LPPP Nanoparticle Layer
3mm Layer formed by spin coating a dispersion of LPPP nanoparticles onto a glass substrate. Particles are closely packed, no cracks can be identified The material was partially removed to show the monolayer ~100 nm

14 LED from Aqueous Emulsions
Preparation of the LED sample structure: Spin casting aqueous PEDOT/PSS solution Drying Spin casting aqueous LPPP nanosphere dispersion Evaporation of cathodes Thickness: Ca:30nm, Al:80nm

15 Nanoparticles and nanoparticle polymer layers
Blends of nanoparticles – nanostructured layers Blend nanoparticles – phase-separation in nanocontainers Some words about photovoltaic devices

16 statistical distribution of particles
Particle Blend Layers Mix dispersion with polymer A and polymer B particles CN-PF:PMMA (1:1) CN-PF:PMMA (1:2) statistical distribution of particles

17 Layer Formation of Particle Blends
+ R 1 H 2 n Low Tg PF LPPP PF forms continuous phase homogenous distribution of LPPP spheres T. Kietzke, D. Neher, K. Landfester, U. Scherf et al., Nat. Mater. 2003

18 Energy Transfer in Particle Blend Layers
PF and LPPP can be excited independently spectral overlap between PF emission and LPPP absorption as-prepared annealed at 200 oC complete transfer of energy in annealed layers

19 Thermal Stability of Blend Structures
mix particles of PF11112 (Tg = RT) and PMMA (Tg=110 oC) different softening temperatures different solubility as prepared annealed at 75 oC annealed at 150 oC

20 AFM Contour Plots (11 nm Increment)
as prepared annealed at 75 oC annealed at 150 oC washed in acetone

21 Nanoparticles and nanoparticle polymer layers
Blends of nanoparticles – nanostructured layers Blend nanoparticles – phase-separation in nanocontainers Some words about photovoltaic devices

22 Preparation of Solar Cells
Start with solution of PFB and F8BT PFB polymer solution electron donor F8BT electron acceptor water + surfactant Nanoparticles which contain both polymers

23 Multicomponent Particles Morphology
PFB F8BT excitation at 380 nm: mainly PFB emission excitation at 462 nm: mainly F8BT emission pronounced asymmetry

24 Exciplex-Spectroscopy on Multicomponent Particles
PFB:F8BT 1:1 D A E e- Recent results by R.H. Friend et al. Exciplex emission at ca. 630 nm Sensitive probe for interface formation Larger exciplex contribution for spin-coated layers Morteani, C. Silva, N. Greenham, R.H. Friend et al. Adv. Mater. 15 (2003) 1708

25 Exciplex-Spectroscopy on Multicomponent Particles
largest interface for blend with lowest F8BT concentration weaker exciplex contribution with increasing higher F8BT concentration  smaller number of excitons reach interface

26 Multicomponent Particle Morphology
F8BT PFB F8BT easily penetrates PFB phase, but PFB remains outside F8BT phase Isolated F8BT phase for higher concentrations small exciton diffusion length on F8BT (ca. 3 nm)* * M. A. Stevens, C. Silva, D. M. Russel, R. H. Friend, Physical Review B 2001, 63,

27 Nanoparticles and nanoparticle polymer layers
Blends of nanoparticles – nanostructured layers Blend nanoparticles – phase-separation in nanocontainers Some words about photovoltaic devices

28 Preparation of Solar Cells
Preparation of the solar cells: Spin casting aqueous PEDOT/PSS solution Drying Spin casting aqueous nanosphere dispersion Evaporation of cathodes Thickness: Ca:30nm, Al:80nm PFB electron donor F8BT electron acceptor

29 Solar Cells based on Blend Particles
Incident-photon-to-converted-electron efficiency (IPCE) Well-resolved contributions from PFB and F8BT

30 IPCE of Blend Particles
h h 380 nm: PFB 445 nm: F8BT Substrate e- h+ ITO Ca A PFB component most active  small exciton diffusion length on F8BT very small IPCE for 5:1 and 1:5  island formation in particle highest efficiency for 1:2  asymmetry of particle morphology

31 Spincoated Blend Layers
PFB:F8BT layers spincoated from xylene 1: : :1 at 400 nm illumination EQE: 4 % % % H.J. Snaith, R.H. Friend et al., Nanoletters 2 (2002) 1353 cylinders of PFB-rich phase dispersed in F8BT rich phase

32 Interfacial Area in Spincoated Layers
at 400 nm illumination Estimate for blend SPNs Interfacial area per film area: with SPNs: optimum conditions achieved but statistics of SPN orientation H.J. Snaith, R.H. Friend et al., Nanoletters 2 (2002) 1353

33 PPV-based Particle Blend Layers
M3EH-PPV CN-Ether-PPV Th. Kietzke, H.H. Hörhold, D. Neher et al., Proc. SPIE 2004, accept. Area = 0.2 cm² 100 mW/cm²

34 Solar Cells Efficiencies E IPCE
polymer solar cell, Univ. Linz Efficiencies E IPCE cryst.-Si typ % (limit 32 %) % wet Grätzel cell  % % polymer/CdSe blend < 7 % % polymer/fullerene blend  5 % % polymer/polymer laminate  1.8 % % polymer/polymer blend < 1.5 % %

35 Conclusion and Outlook
Nanoparticles of conjugated polymers:  fabrication of polymer particles via miniemulsion process  formation of dense solid layers from aqueous media  nanostructured polymer layers via particle blends  phase-separation in nanocontainers  control of solar cell efficiencies via particle composition Outlook:  better understanding of particle morphology  alternative deposition methods  components with high electron mobilities  single particle properties

36 A. Heilig Phys. Chem., MPI-KG, Golm
H. H. Hörhold University of Jena T. Piok, S. Gamerith, Ch. Gadermaier, F. P. Wenzl, E.J.W. List, University of Graz M. Kumke, H.G. Löhmannsröben University of Potsdam Funding: VW-Foundation, MPG, BMBF, Fond der Chemischen Industrie


Download ppt "Semiconducting Polymer Nanoparticles: Spectroscopy and Devices"

Similar presentations


Ads by Google