High and Low Bandgap Polyfluorene Copolymers for Organic Solar Cells Xiwen Chen

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1 High and Low Bandgap Polyfluorene Copolymers for Organic Solar Cells Xiwen Chen Senior Research Scientist Commonwealth Scientific and Industrial Research Organsation (CSIRO)

2 Outlines Electron Transport Materials for OPV anostructured Polymer Solar Cells Triplet for OPV Side Chain Effects of High and Low Bandgap Polyfluorene Copolymers on OPV Summary CSIRO Flexible Electronics Theme 2

3 BCP in OPVs BCP Peumans, P.; Bulovic, V.; Forrest, S. R. Appl. Phys. Lett. 2000, 76,

4 BCP in OPVs BCP ITO/C60/BCP/Al, Vbi = 0.85 V ITO/C60/Al, Vbi = 0.25 V Gommans, H. et al. Adv. Funct. Mater. 2008, 18,

5 Oxadiazole Electron Transport Moiety for PLEDs Oxadiazole increase electron mobility! (TOF) Lee, Y. Z.; Chen, X.; Chen, S. A.; Wei, P. K.; Fann, W. S. JACS 2001,123,2296. Huang, S. P., Liao, J. L.; Tseng, H. E.; Jen, T. H.; Liu, C. Y.; Chen, S. A. Synth. Met. 2006, 156,

6 Triazole as Electron Transport Material for PLEDs C(CH 3 ) 3 O(CH 2 ) 10 O OCH 2 CH(C 2 H 5 )(C 4 H 9 ) T0: a=0, b=1 (MEH-PPV) T25 : a=0.25, b=0.75 T40 : a=0.4, b=0.6 CH 3 O a CH 3 O b T60 : a=0.6, b=0.4 T80 : a=0.8, b=0.2 T100 : a=1, b=0 (MTAD-PPV) Voc ITO/T60/Al 1.2 V ITO/MEH-PPV/Al 0.9 V PPV TAZ ITO Al Yu, L. S.; Chen, S. A. Adv. Mater. 2004, 16,

7 Fullerene with a Triazole Electron mobility (SCLC): 2.2*10-8 m 2 /V s Chen, X.; Liu, C. Y.; Jen, T. H.; Chen, S. A.; Holdcroft, S. Chem. Mater. 2007, 19,

8 Polythiophene Graft Polymer-TAZC60 Blends O m S 0.05n S 0.95n m~3.3 n=~149 P3HT-g-PVTAZ (11) Zhou, Z.; Chen, X.; Holdcroft, S. JACS 2008, 130, Chen, X. et al. MRS Fall Meeting, ov 26-30, 2007, Boston, USA. 8

9 anostructured Polymers (a) (d) 51 nm 8 8 8µm (b) 8 µm 4 8 µm 4 µm 8 0 µm 8 8 (c) (e) 45 nm 8 8 8µm 88µm 48µm 1). Han, X.; Chen, X.; Holdcroft, S. Adv. Mater. 2007, 19, ). Han, X.; Chen, X.; Holdcroft, S. submitted. 4 µm µm 8 8

10 anostructured Polymers Solar Cells Pure phases Stable morphology Han, X.; Chen, X.; Holdcroft, S. submitted. 10

11 First Conjugated Polymers with Iridium Complexes for PLEDs m n p q O O Ir S O O Ir 2 2 Citation >211 Chen, X.; Liao, J. L.; Liang, Y.; Ahmed, M. O.; Tseng, H. E.; Chen, S. A. JACS 2003, 125,

12 Iridium-containing Polymer for OPVs PL spectra of films Schulz, G. L.; Holdcroft, S. Chem. Mater. 2008, 20,

13 Iridium emission from the copolymer 13

14 Red Shift the Main Chain Absorption Schulz, G. L. Ph.D thesis, Simon Fraser University,

15 Red Shift the Main Chain Absorption Schulz, G. L. Ph.D thesis, Simon Fraser University,

16 PD Triplet in OPV: recent literature Luhman, W. A.; Holmes, R. J. Appl. Phys. Lett. 2009, 94,

17 High Bandgap Polymer F6T Mn = 8.7 k, PDI= 1.7 Eg = 2.4 ev TEM of film F6T2:PCBM (1:4) Schula, G. L.; Chen, X.; Holdcroft, S. Appl. Phys. Lett. 2009, 94,

18 High Bandgap Polyfluorene copolymer F6T2 ITO/PEDOT/F6T2:PCBM (1:4)/Ca/Al Polymer J SC FF V OC ma/cm 2 V PCE % EQE Method F6T F8T P3HT (Rieke) YY s solvent annealing Blend hole mobility by SCLC: 3x10-8 m 2 /Vs Additive does not work. low molecular weight? eed optimized! Schula, G. L.; Chen, X.; Holdcroft, S. Appl. Phys. Lett. 2009, 94,

19 Side Chain Effect on Benzothiadiazole Polymers S S 0.65 S 0.35 PFO-DBT35 Polymer Mn K Da λ ab nm Q PL V oc V J sc FF PCE ma/cm 2 % PFDTBT /A PFO- DBT PFOR50S This work Ref Small red-shifted absorption and emission (7~8 nm) from solution to solid film reduced interchain interaction 1. Inganas, O. et al. Adv. Mater. 2003, 15, Cao, Y. et al. Appl. Phys. Lett. 2004, 84, This work: Chen, X.; Schulz, G. L.; Han, X.; Zhou, Z.; Holdcroft, S. J. Phys. Chem. C 2009, 113,

20 Combination of High and Low Bandgap Materials For example: Heeger, et al. Tandem solar cells Inganas, et al. Reflective solar cells Arnold Tamayo: mixed donor blends 20

21 Summary Organic electron transport materials for polymer solar cells need test in multilayer devices first. Is it a working concept for polymer solar cells? We demonstrated the concept of nanostructured polymer solar cells. eed further evidence to see if the triplet is good or not for polymer solar cells. Increasing the interchain interaction can improve the PV device performance. 21

22 CSIRO people 22

23 CSIRO Flexible Electronics Theme Stream leader Dr. Mark Bown OLEDS OFETS Theme Leader Dr. Gerry Wilson ~36 staffs Stream leader Dr. Scott Watkins OPVs Gratzel cells CSIRO Fellows Prof. Andrew Holmes Dr. Ezio Rizzardo Other Research Scientists Dr. Graeme Moad Dr. Ming Chen Dr. Birendra Singh Dr. Giovanni Fanchini Dr. Kazunori Ueno Dr. Richard Evans Dr. Mei Gao Dr. Gavin Collis Dr. Chris Dunn Dr. Kevin Winzenberg Dr. Sven Dr. Juo-Hao Li 23.

24 Victorian Government Sustainable Energy Research and Development (Udo Bach etc) (A. B. Holmes, etc) $6M in funding from the Victorian Government matching $6M from the institutions to create VICOSC, the Victorian Organic Solar Cell Consortium 24

25 Acknowledgements Prof. Steven Holdcroft, Dr. Xu Han, Dr. Gisela Schulz, Zhongyuan Zhong, etc at Simon Fraser University Prof. Show-An Chen, Dr. Jin-Long Liao, Dr. Yuh- Zheng Lee, etc at ational Tsing-Hua University 25

26 CSIRO Molecular and Health Technologies Business CSIRO Future Unit ame Manufacturing Flagship Business Unit ame Presenter s Xiwen Chenname Presenter s name Presenter s title Presenter s title Phone: Phone: Xiwen.Chen@csiro.au Phone: Web: name.name@csiro.au name.name@csiro.au Web: Web: Thank you Thank you Contact Us Contact CSIRO Phone: or Phone: or Enquiries@csiro.au Web: Enquiries@csiro.au Web:

27 XRD of F6T2 Counts F6T Position [ 2Theta] (Copper (Cu)) [Å] [Å] [Å] [Å]