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Jpcl 10.1021 jz300723h dai presentation


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Sulfated Graphene Oxide as a Hole-Extraction Layer in High-Performance Polymer Solar Cells
J. Phys. Chem. Lett., 2012, 3 (14), pp 1928–1933
DOI: 10.1021/jz300723h
In this study, we have rationally designed and successfully developed sulfated graphene oxide (GO–OSO3H) with −OSO3H groups attached to the carbon basal plane of reduced GO surrounded with edge-functionalized −COOH groups. The resultant GO–OSO3H is demonstrated to be an excellent hole extraction layer (HEL) for polymer solar cells (PSCs) because of its proper work function for Ohmic contact with the donor polymer, its reduced basal plane for improving conductivity, and its −OSO3H/–COOH groups for enhancing solubility for solution processing. Compared with that of GO, the much improved conductivity of GO–OSO3H (1.3 S m–1 vs 0.004 S m–1) leads to greatly improved fill factor (0.71 vs 0.58) and power conversion efficiency (4.37% vs 3.34%) of the resulting PSC devices. Moreover, the device performance of GO–OSO3H is among the best reported for intensively studied poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) devices. Our results imply that judiciously functionalized graphene materials can be used to replace existing HEL materials for specific device applications with outstanding performance.

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Jpcl 10.1021 jz300723h dai presentation

  1. 1. Sulfated Graphene Oxide as a Hole-Extraction Layer in High-Performance Polymer Solar Cells Jun Liu, Yuhua Xue and Liming Dai* COOH COOH HOOC COOH HOOC COOH Al OH O OH OSO3H OSO3H Ca HOOC O OH COOH HOOC OH COOH O OH P3HT:PCBM HOOC COOH COOH HOOC OSO3H COOH COOH GO GO-OSO3H ITODepartment of Macromolecular Science and Engineering, Department of Chemical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA J. Phys. Chem. Lett. 2012, 3, 1928 -1933. 1
  2. 2. Hole-Extraction LayerRequirement for Hole-Extraction Layer: Minimizing hole extraction barrier; Blocking electrons; Al Alter morphology of the active layer; Ca Solution processability; P3HT:PCBM High conductivity. ITOGraphene oxide as for Hole-Extraction Layer: Low conductivity; Large series resistance and low fill factor of the devices. Proprietary and Confidential 2 American Chemical Society
  3. 3. Design of GO-OSO3H COOH COOH HOOC COOH HOOC COOH OH OH O OSO3H O O H2SO4 (SO3) OSO3H HOOC COOH HOOC COOH OH O OH OSO3H O HOOC COOH HOOC COOH COOH COOH GO GO-OSO3H  Reduced basal plane: improved conductivity;  -OSO3H groups: improved acidicity;  -OSO3H and –COOH groups: improved solubility.Proprietary and Confidential 3American Chemical Society
  4. 4. Reduced Basal Plane O1s GO C-O C-C C1s GO C=O 160 200 240 COOH C1s O1s GO-OSO3H C-C GO-OSO3H C-O 160 200 240 C-S S2p S2s COOH 0 200 400 600 290 285 280 Binding energy (eV) Binding Energy (eV) XPS: Less O content XPS C1s: Less C-O/C-C ratio 11.5o GO GO GO-OSO3H Conductivity: diffraction (a.u.)intensity (a.u.) GO-OSO3H 22.6 o GO: 0.004 S/m GOOSO3H: 1.3 S/m 500 1000 1500 2000 20 40 60 80 -1 wavenumber (cm ) 2 (deg) Raman: larger ID/IG ratio XRD: smaller π- π distance Proprietary and Confidential 4 American Chemical Society
  5. 5. Solution Processability High quality film Single-layer graphene sheets after spincoatingProprietary and Confidential 5American Chemical Society
  6. 6. Device Efficiency HEL VOC JSC FF PCE Rs (V) (mA/cm2) (%) ( cm2) PEDOT:PSS 0.60 10.35 0.71 4.39 1.4 GO 0.61 9.64 0.58 3.34 3.1 GO-OSO3H 0.61 10.15 0.71 4.37 1.2 0Compared with the GO-based current density (mA/cm2) -3 PEDOT:PSSdevice, its GO−OSO3H counterpart GO GO-OSO3H -6exhibits a much lower series -9resistance and hence significantlyimproved FF and PCE. -12 0.0 0.2 0.4 0.6 voltage (V)Proprietary and Confidential 6American Chemical Society
  7. 7. Thicknesses Dependence GO-OSO3H GO current density (mA/cm ) current density (mA/cm ) 2 2 0 0 -3 2 nm 2 nm -3 4 nm 4 nm 6 nm 6 nm -6 -6 -9 -9 -12 -12 0.0 0.2 0.4 0.6 0.0 0.2 0.4 0.6 voltage (V) voltage (V) No dependence Efficiency decreaseProprietary and Confidential 7American Chemical Society
  8. 8. ConclusionsRational-design and preparation of GO-OSO3H.The reduced basal plane, the increased acidicity, and the goodsolution processability of GO-OSO3H.GO-OSO3H is an excellent hole extraction material for PSCs. Acknowledgement Air Force Office of Scientific Research (FA9550-12-1- 0069) under the Program Manager – Dr. Charles Lee Wenzhou Medical College, Zhejiang Innovation Team from Department of Education (T200917), Ministry of Education of China (IRT1077, 211069, and 20103321120003), National “Thousand Talents Program” of China, Ministry of Science and Technology of China (2009DFB30380), NSFC- NSF MWN (NSF-DMR 1106160)Proprietary and Confidential 8American Chemical Society