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Morphoso Evaluation Platform for Polymeric Solar Cells
U. Würfel, coord. Fraunhofer Institute for
Solar Energy Systems (ISE), Freiburg, Germany
O. Inganäs and Fengling Zhang
Biomolecular and organic electronics, IFM, and Center of Organic Electronics (COE), Linköpings Universitet,
Sweden
R. Österbacka Physics, Department of Natural Sciences and Center for Functional Materials, Åbo Akademi University, Finland
Fraunhofer ISE Dr. U. Würfel (coord.) M.Sc. S. Mühlbach M.Sc. F. Stelzl M.Sc. M. Schubert Dr. B. Zimmermann M.Sc. H.-F.
Schleiermacher
Linköping University Prof. O. Inganäs Dr. F. Zhang Dr. L.M. Andersson Dr. K. Tvingsted Dr. Yi Zhou Dr. C. Müller M.Sc. V. Andersson M.Sc. Jens Lorrmann
Åbo Akademi Prof. R. Österbacka M.Sc. M. Nyman M.Sc. H. Aarnio M.Sc. D. Tobjörk M.Sc. S. Sanden
Groups
PhD students/post docs
•LIU 1 PhD and 3 Postdoc, •
•Åbo 1 PhD,
•ISE 1 PhD, 2 postdoc, 2 master students
Organization and cooperation •5 project meetings,(LiU, Åbo, ISE, LiU, Åbo) •2 video Conferences (2010 May and August, Eyjafjallajökull!!!) •1 conference via skype.
•Researchers visiting •Mathias, (three days in ÅA, one week in ISE), Fengling (two
months in ISE) and Mattias (two weeks in ISE) •Sebastian in Åbo (2 weeks) and in LiU (three days)
•Round-robin tests of samples
Aluminium
Photoactive layer Polymer Anode
ITO Substrate
Donor
Acceptor
Organic solar cell – Working principle
Efficiency development
Objectives
•To establish an evaluation platform for organic solar cells that integrates
› Device modelling, › processing, › characterisation
•to find the theoretical and experimental correlation between
› the thin film process, › its nanomorphology and › the charge carrier generation and transport
Solar cells
WP1 Modelling
WP2 New device architecture
WP3: Study of process parameters
WP4 Morphology
WP6 Durability and ageing
WP5 Optical and electrical characterization
Tasks
WP1 Modelling (ISE/LiU)
•Optical absorption under non-normal incidence in isotropic and anisotropic multilayer thin film structures •Development of coupled continuum models for optical and
electrical processes •Optical and electrical models •Good agreement between simulations and experiments
(especially ageing and new hole contacts for different polymers •Modelling of transient processes
› Simulation of CELIV experiments
Publications: (1)Andersson, V.; Tvingstedt, K.; Inganas, O. Optical modeling of a folded
organic solar cell. Journal Of Applied Physics 2008, 103. (2)Andersson, B. V.; Persson, N. K.; Inganas, O. Comparative study of
organic thin film tandem solar cells in alternative geometries. Journal Of Applied Physics 2008, 104.
WP2 New device architecture (LiU/ISE) •Structured substrates (µm- and cm-region) •Inverted layer sequence (ITO free cells): much work done on new contact materials, especially for lower lying HOMOs of different polymers. These cells underwent ageing experiments WP6
PEDOT:PSS Absorber Lithium Fluoride Aluminium
Substrate ITO
Metalgrid (10-20% area loss)
PEDOT:PSS Absorber Titanium Aluminium Substrate
„Standard“
„Inverted“ Light
Light
Wuerfel, ISE
Results (LiU/ISE) •V-tandem cells •Simulation of V-cell performance compared to flat cells during a full summer
Andersson, B. V. et al, Solar Energy, 2011, 85,1257–1263.
WP3: Study of process parameters
D. Tobjörk, et al., Mater. Res. Soc. Symp. Proc,. 1091, 1091-AA05-45 (2008)
Jsc (mA/cm2)
Voc (V)
FF (%)
PCE (%)
A (mm2)
t (nm)
RG coated 2.4 0.56 56.1 0.74 11 ~100
Spin coated 2.6 0.57 56.4 0.84 8 ~120
Initial study done, then stopped
WP4 Morphology •Additive effects on morphology and performance of solar cells •3D-Transmission Electron Microscopy (TEM) •Thermal treatment effects on device performance via
morphology variation
Publications: (1) Andersson, B. V.; Herland, A.; Masich, S.; Inganas, O. Imaging of the 3D
Nanostructure of a Polymer Solar Cell by Electron Tomography. Nano Letters 2009, 9, 853-855
(2) Barrau, S.; Andersson, V.; Zhang, F. L.; Masich, S.; Bijleveld, J.; Andersson, M. R.; Inganas, O. Nanomorphology of Bulk Heterojunction Organic Solar Cells in 2D and 3D Correlated to Photovoltaic Performance. Macromolecules 2009, 42, 4646-4650.
(3) R. Qin, W. Li, C. H. Li, C. Du, C. Veit, H. F. Schleiermacher, M. Andersson, Z.S. Bo, Z. P. Liu, O. Inganas, U. Wuerfel, F. L. Zhang, J. Am. Chem. Soc. 2009, 131,14612-14613
(4)C. Müller, E. Wang, L. M. Andersson, K. Tvingstedt, Y. Zhou, M. R. Andersson, O. Inganäs, Adv. Funct. Mater. 2010, 20, 2124-2131.
(5) C. Müller, J. Bergqvist, K. Vandewal, K. Tvingstedt, O. Inganäs, M. Campoy-Quiles, A.-S. Anselmo, E. Moons (in preparation).
"Temperature stability of Liquid-Crystalline Polymer / Fullerene Organic Photovoltaic Blends“
Results (LiU)
•Electron tomography developed that give information about phase separation on the nanoscale •Important for the input in models and analyses
Andersson, B. V.;et al., Nano Letters 2009, 9, 853-855.
Results (LiU)
• Blend nanostructures also followed by calorimetryand birefringence in the blends.
• The precision of calorimetric measurements were imporved using ellipsometry under a temperature scan.
• This approach has great attraction for understanding both charge generation and charge transport conditions.
• Stochiometry variations have been used to create complete phase diagrams
Müller, C.et al., Adv.Func.Mat. 2011.
0 10 20 30 40
Mn (kg·mol-1)
0
1
2
3
pow
er c
onve
rsio
n ef
ficie
ncy
(%)
oligomer polymer
WP5 Optical and electrical characterization (ÅA/LiU/ISE) •Characterize the same samples in three groups (Round-robin
test) •CELIV(Charge Extraction by Linearly Increasing Voltage)
measurements (on fresh and aged cells) › Poster presentaton
•Time-of-Flight (TOF) •Impedance spectroscopy •Pulsed photocurrent •Combined electro-optical setup •Photoinduced Absorption
Results (LiU): The effect on charge generation of the charge transfer state
•The identification of an intermediate state of charge generation the s.c. charge transfer state of lower emission energy has been reported. •It was shown that the field
dependence of charge generation is different for charge transfer states and single phase excited states, and that PL quenching thus can be used as a probe for morphology.
Tvingstedt et al., Journal of The American Chemical Society 2009, 131, 11819
Results: Spontaneous dipole formation at the interface between P3HT/PCBM •Spontaneous energy level
alignment at interfaces by charge transfer •Electrons want to minimize
their energy › Charge transfer from the
P3HT EICT+ to PCBM EICT- › Dipole formation!
•Explanes in part the observed reduced geminate recombination
Aarnio et al., Adv. Energy Mater. (2011) DOI: 10.1002/aenm.201100074 ÅA, LiU
WP6 Durability and ageing (ISE/LiU/ÅA) •ISE performed many ageing tests under different conditions
with a variety of different barrier materials: › UV › Thermal stress (85 C in the dark) › Continuous illumination (up to 7000h corresponding to 7 years
outdoor) •A Round robin test of devices were sent out and tested in
all laboratories for making sure the measurements OK •Valuable long-term stability tests were performed and
Results (ISE/LiU)
•The Effect of Additive on HXS/PCBM Photovoltaic Devices: Performance, Morphology, Charge Generation, Transport and Shelf-stability
-50 0 50 100 150 200 250 300 350 400
3.0
3.5
4.0
4.5
5.0
5.5
DCB DCB/DIO
PCE
(%)
Day (d)
Weiwei Li, et al., : “The Effect of additive on performance and shelf-stability of HSX-1/PCBM photovoltaic devices” Organic Electronics, 2011, 12(9), 1544–1551. (ISE, LiU) ISE/LiU
Results (ÅA/ISE)
•Effect of ageing on the charge tarnsport and recombination of APFO3:PCBM cells •See poster outside M. Nyman et al., -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5
-5,0
-2,5
0,0
2,5
5,0
J [m
A/cm
2 ]
U [V]
Pristine dark Pristine light Degraded dark Degraded light
M. Nyman, S. Muehlbach et. al., Energy procedia, at press (ISE, ÅA)
Summary
•New results giving combined information around morphology, electro-optical properties and device performance has been achieved •Advanced the understanding of fundamental processes in
organic solar cells •Meanwhile the efficiencies has doubled
› Not only thanks to Morfoso, but...
Thank you!
Advantage with N-INNER
This type of funding is among the few available where a smaller number of (international) groups can collaborate effectively. Neither EU nor National funding do provide this possibility! We think that the scientific ”quality” is fostered due to more intense discussions and a better interchange of ideas.
Overall list of publications (26) 1. Andersson, B. V.; Huang, D. M.; Moule, A. J.; Inganas, O. An optical spacer is no panacea for light collection in organic solar cells. Applied Physics Letters 2009, 94. 2. Tvingstedt, K.; Andersson, V.; Zhang, F.; Inganas, O. Folded reflective 3. tandem polymer solar cell doubles efficiency. Applied Physics Letters 2007, 91, 123514. 4. Andersson, B. V.; Persson, N. K.; Inganas, O. Comparative study of 5. organic thin film tandem solar cells in alternative geometries. Journal Of Applied Physics 2008, 104. 6. Andersson, V.; Tvingstedt, K.; Inganas, O. Optical modeling of a folded organic solar cell. Journal Of Applied Physics 2008, 103. 7. Andersson, B. V.; Wuerfel, U.; Inganäs, O. Full day modelling of Vshaped organic solar cell. Solar Energy 2010, In Press, Corrected Proof. 8. Zhou, Y. H.; Zhang, F. L.; Tvingstedt, K.; Tian, W. J.; Inganas, O. Multifolded polymer solar cells on flexible substrates. Applied Physics Letters 2008, 93. 9. Andersson, B. V.; Herland, A.; Masich, S.; Inganas, O. Imaging of the 3D Nanostructure of a Polymer Solar Cell by Electron Tomography. Nano Letters 2009, 9, 853-855. 10. (8) Barrau, S.; Andersson, V.; Zhang, F. L.; Masich, S.; Bijleveld, J.; Andersson, M. R.; Inganas, O. Nanomorphology of Bulk Heterojunction Organic Solar Cells in 2D and 3D
Correlated to Photovoltaic Performance. Macromolecules 2009, 42, 4646-4650. 11. Qin, R. P.; Li, W. W.; Li, C. H.; Du, C.; Veit, C.; Schleiermacher, H. F.; Andersson, M.; Bo, Z. S.; Liu, Z. P.; Inganas, O.; Wuerfel, U.; Zhang, F. L. A Planar 12. Copolymer for High Efficiency Polymer Solar Cells. Journal Of The American Chemical Society 2009, 131, 14612. 13. Li, W. W.; Zhou, Y.; Andersson, B. V.; Andersson, L. M.; Thomann, Y.; Veit, C.; Tvingstedt, K.; Qin, R. P.; Bo, Z. S.; Inganäs, O.; Würfel, U.; Zhang, F. Performance Enhancement of
HSX-1/PCBM Bulk Heterojunction Photovoltaic Devices through Morphology Optimization by an Additive. submitted to Organic Electronics 2011. 14. Wang, E. G.; Hou, L. T.; Wang, Z. Q.; Hellstrom, S.; Zhang, F. L.; Inganas, O.; Andersson, M. R. An Easily Synthesized Blue Polymer for High-Performance Polymer Solar Cells.
Advanced Materials 2010, 22, 5240. 15. Hou, L. T.; Wang, E. G.; Bergqvist, J.; Andersson, B. V.; Wang, Z. Q.; Müller, C.; Campoy-Quiles, M.; Andersson, M. R.; Fengling, Z.; Inganäs, O. Lateral Phase Separation Gradients
in Spin-Coated Thin Films of High Performance Polymer:Fullerene Photovoltaic Blends. in submission 2011. 16. Müller, C.; Bergqvist, J.; Vandewal, K.; Tvingstedt, K.; Anselmo, A. S.; Magnusson, R.; Alonso, M. I.; Moons, E.; Arwin, H.; Campoy-Quiles, M.; Inganäs, O. Phase Behavior of
Liquid-Crystalline Polymer / Fullerene Organic Photovoltaic Blends: Thermal Stability and Miscibility. submitt, Adv.Func.Mat. 2011. 17. Zhou, Y.; Tvingstedt, K.; Zhang, F. L.; Du, C. X.; Ni, W. X.; Andersson, M. R.; Inganas, O. Observation of a Charge Transfer State in Low-Bandgap Polymer/Fullerene Blend
Systems by Photoluminescence and Electroluminescence Studies. Advanced Functional Materials 2009, 19, 3293-3299. 18. Tvingstedt, K.; Vandewal, K.; Gadisa, A.; Zhang, F. L.; Manca, J.; Inganas, O. Electroluminescence from Charge Transfer States in Polymer Solar Cells. Journal Of The American
Chemical Society 2009, 131, 11819.. 19. Tvingstedt, K.; Vandewal, K.; Zhang, F. L.; Inganas, O. On the Dissociation Efficiency of Charge Transfer Excitons and Frenkel Excitons in Organic Solar Cells: A Luminescence
Quenching Study. Journal of Physical Chemistry C 2010, 114, 21824. 20. Andersson, L. M.; Inganas, O. From short to long - Optical and electrical transients in photovoltaic bulk heterojunctions of polyfluorene/fullerenes. Chemical Physics 2009, 357,
120-123. 21. Andersson, L. M.; Müller, C.; Badada, B. H.; Zhang, F. L.; Wuerfel, U.;Inganäs, O. Correlation between Charge-Carrier Mobility and Fill Factor in Geminate Recombination Limited
Organic Solar Cells. in submission 2011. 22. Andersson, L. M. Charge transport and energetic disorder in polymer:fullerene blends. Organic Electronics 2010, 12, 300-305. 23. Lorrmann, J.; Badada, B. H.; Inganäs, O.; Dyakonov, V.; Deibel, C. Charge Carrier Extraction by Linearly Increasing Voltage: Analytic framework and ambipolar transients.
J.Appl.Phys. 2010, in press. 24. H. Aarnio, P. Sehati, S. Braun, M. Nyman, M. deJong, M. Fahlman, and R. Österbacka, ”Spontaneous charge transfer and dipole formation at the interface
between P3HT and PCBM”, in press Advanced Energy Materials (2011). DOI: 10.1002/aenm.201100074 25. H. Aarnio and R. Österbacka, “Bimolecular recombination in regioregular and regiorandom poly(3-hexylthiophene):PCBM using photoinduced absorption spectroscopy”, Submitted to
Proceedings of 2011 Bilateral Conference on Energy, Energy Proceedings, (2011).
26. M. Nyman, S. H. Aarnio and R. Österbacka, “The Effect of Degradation on the Active Layer in APFO3:PCBM Solar Cells”, Submitted to Proceedings of 2011 Bilateral Conference on Energy, Energy Proceedings,(2011).