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Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure

Nature Photonics volume 6, pages 591–595 (2012)Cite this article

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Abstract

Polymer-fullerene bulk heterojunction solar cells (PSCs) are currently attracting a great deal of attention and gaining increasing importance, having already shown great promise as renewable, lightweight and low-cost energy sources1,2,3,4. Recently, the power-conversion efficiency of state-of-the-art PSCs has exceeded 8% in the scientific literature5. However, to find viable applications for this emerging photovoltaic technology, further enhancements in the efficiency towards 10% (the threshold for commercial applications) are urgently required6. Here, we demonstrate highly efficient PSCs with a certified efficiency of 9.2% using an inverted structure, which simultaneously offers ohmic contact for photogenerated charge-carrier collection and allows optimum photon harvest in the device. Because of the ease of use and drastic boost in efficiency provided by this device structure, this discovery could find use in fully exploiting the potential of various material systems, and also open up new opportunities to improve PSCs with a view to achieving an efficiency of 10%.

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Figure 1: Device structure and energy levels of the inverted-type PSCs.
Figure 2: Device performances of the inverted structure (ITO/PFN interlayer/active layer/MoO3 (10 nm)/Al) PTB7:PC71BM PSCs and the conventional device (ITO/PEDOT:PSS/active layer/PFN interlayer/Ca/Al).
Figure 3: Comparison of calculated optical absorption profile for conventional and inverted devices.
Figure 4: J–V characteristics for semitransparent PSCs under front- and rear-side AM 1.5G (1,000 W m−2) illumination.

References

  1. Park, S. H. et al. Bulk heterojunction solar cells with internal quantum efficiency approaching 100%. Nature Photon. 3, 297–303 (2009).

    Article  ADS  Google Scholar 

  2. Chen, H-Y. et al. Polymer solar cells with enhanced open-circuit voltage and efficiency. Nature Photon. 3, 649–653 (2009).

    Article  ADS  Google Scholar 

  3. Liang, Y. Y. et al. For the bright future-bulk heterojunction polymer solar cells with power conversion efficiency of 7.4%. Adv. Mater. 22, E135–E138 (2010).

    Article  Google Scholar 

  4. Seo, J.-H. et al. Improved high-efficiency organic solar cells via incorporation of a conjugated polyelectrolyte interlayer. J. Am. Chem. Soc. 133, 8416–8419 (2011).

    Article  Google Scholar 

  5. He, Z. C. et al. Simultaneous enhancement of open-circuit voltage, short-circuit current density and fill factor in polymer solar cell. Adv. Mater. 23, 4636–4643 (2011).

    Article  Google Scholar 

  6. Brabec, C. J. et al. Polymer–fullerene bulk-heterojunction solar cells. Adv. Mater. 22, 3839–3856 (2010).

    Article  Google Scholar 

  7. Li, G., Chu, C. W., Shrotriya, V., Huang, J. & Yang, Y. Efficient inverted polymer solar cells. Appl. Phys. Lett. 88, 253503 (2006).

    Article  ADS  Google Scholar 

  8. Waldauf, C. et al. Highly efficient inverted organic photovoltaics using solution based titanium oxide as electron selective contact. Appl. Phys. Lett. 89, 233517 (2006).

    Article  ADS  Google Scholar 

  9. Huang, J., Li, G. & Yang, Y. A semi-transparent plastic solar cell fabricated by a lamination process. Adv. Mater. 20, 415–419 (2008).

    Article  Google Scholar 

  10. Ameri, T. et al. Fabrication, optical modeling, and color characterization of semitransparent bulk-heterojunction organic solar cells in an inverted structure. Adv. Funct. Mater. 20, 1592–1598 (2010).

    Article  Google Scholar 

  11. Yang, T. B. et al. Solution-processed zinc oxide thin film as a buffer layer for polymer solar cells with an inverted device structure. J. Phys. Chem. C 114, 6849–6853 (2010).

    Article  Google Scholar 

  12. Sun, Y. M., Seo, J. H., Takacs, C. J., Seifter, J. & Heeger, A. J. Inverted polymer solar cells integrated with a low-temperature-annealed sol-gel-derived ZnO film as an electron transport layer. Adv. Mater. 23, 1679–1683 (2011).

    Article  Google Scholar 

  13. Small, C. E. et al. High-efficiency inverted dithienogermole–thienopyrrolodione-based polymer solar cells. Nature Photon. 6, 115–120 (2012).

    Article  ADS  Google Scholar 

  14. Na, S-I., Kim, T. S., Oh, S-H., Kim, J-Y., Kim, S-S. & Kim, D-Y. Enhanced performance of inverted polymer solar cells with cathode interfacial tuning via water-soluble polyfluorenes. Appl. Phys. Lett. 97, 223305 (2010).

    Article  ADS  Google Scholar 

  15. Choi, H. S. et al. Combination of titanium oxide and a conjugated polyelectrolyte for high-performance inverted-type organic optoelectronic devices. Adv. Mater. 23, 2759–2763 (2011).

    Article  Google Scholar 

  16. Zhu, Y. X., Xu, X. F., Zhang, L. J., Chen, J. W. & Cao, Y. High efficiency inverted polymeric bulk-heterojunction solar cells with hydrophilic conjugated polymers as cathode interlayer on ITO. Sol. Ener. Mater. Sol. Cells 97, 83–88 (2012).

    Article  Google Scholar 

  17. Cheng, Y.-J., Hsieh, C.-H., He, Y. J., Hsu, C.-S. & Li, Y. F. Combination of indene–C60 bis-adduct and cross-linked fullerene interlayer leading to highly efficient inverted polymer solar cells. J. Am. Chem. Soc. 132, 17381–17383 (2010).

    Article  Google Scholar 

  18. Hsieh, C.-H. et al. Highly efficient and stable inverted polymer solar cells integrated with a cross-linked fullerene material as an interlayer. J. Am. Chem. Soc. 132, 4887–4893 (2010).

    Article  Google Scholar 

  19. Park, J. S. et al. Efficient hybrid organic-inorganic light emitting diodes with self-assembled dipole molecule deposited metal oxides. Appl. Phys. Lett. 96, 243306 (2010).

    Article  ADS  Google Scholar 

  20. Xu, Z. et al. Vertical phase separation in poly(3-hexylthiophene): fullerene derivative blends and its advantage for inverted structure solar cells. Adv. Funct. Mater. 19, 1227–1234 (2009).

    Article  Google Scholar 

  21. Campoy-Quiles, M. et al. Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends. Nature Mater. 7, 158–164 (2008).

    Article  ADS  Google Scholar 

  22. Huang, F., Wu, H. B., Wang, D. L., Yang, W. & Cao, Y. Novel electroluminescent conjugated polyelectrolytes based on polyfluorene. Chem. Mater. 16, 708–716 (2004).

    Article  Google Scholar 

  23. Wu, H. B. et al. Efficient electron injection from a bilayer cathode consisting of aluminum and alcohol-/water-soluble conjugated polymers. Adv. Mater. 16, 1826–1830 (2004).

    Article  Google Scholar 

  24. Huang, F., Wu, H. B. & Cao, Y. Water/alcohol soluble conjugated polymers as highly efficient electron injection/transporting layer in optoelectronic devices. Chem. Soc. Rev. 39, 2500–2521 (2010).

    Article  Google Scholar 

  25. Wu, H. B., Huang, F., Peng, J. B. & Cao, Y. High-efficiency electron injection cathode of Au for polymer light-emitting devices. Org. Elect. 6, 118–128 (2005).

    Article  Google Scholar 

  26. Ishii, H., Sugiyama, K., Ito, E. & Seki, K. Energy level alignment and interfacial electronic structures at organic/metal and organic/organic interfaces. Adv. Mater. 11, 605–625 (1999).

    Article  Google Scholar 

  27. Braun, S., Salaneck, W. R. & Fahlman, M. Energy-level alignment at organic/metal and organic/organic interfaces. Adv. Mater. 21, 1450–1472 (2009).

    Article  Google Scholar 

  28. Greiner, M. T. et al. Universal energy-level alignment of molecules on metal oxides. Nature Mater. 11, 76–81 (2012).

    Article  ADS  Google Scholar 

  29. Blom, P. W. M., Mihailetchi, V. D., Koster, L. J. A. & Markov, D. E. Device physics of polymer:fullerene bulk heterojunction solar cells. Adv. Mater. 19, 1551–1566 (2007).

    Article  Google Scholar 

  30. Shuttle, C. G., Hamilton, R., O'Regan, B. C., Nelson, J. & Durrant, J. R. Charge-density-based analysis of the current–voltage response of polythiophene/fullerene photovoltaic devices. Proc. Natl Acad. Sci. USA 107, 16448–16452 (2010).

    Article  ADS  Google Scholar 

  31. Pettersson, L. A. A., Lucimara, S. R. & Inganas, O. Modeling photocurrent action spectra of photovoltaic devices based on organic thin films. J. Appl. Phys. 86, 487–496 (1999).

    Article  ADS  Google Scholar 

  32. Shrotriya, V. et al. Accurate measurement and characterization of organic solar cells. Adv. Funct. Mater. 16, 2016–2023 (2006).

    Article  Google Scholar 

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Acknowledgements

The authors thank Min Yun of the National Center of Supervision and Inspection on Solar Photovoltaic Products Quality for device performance verification, Fangyan Xie of Sun Yat-San University for XPS measurements, Bin Wu of South China University of Technology for XRD measurements, Yanhong Meng for refractive index and extinction coefficient measurements, Xueqing Xu for reflectance measurements and Feng Liu for critical reading of the manuscript. H.W. and Y.C. acknowledge financial support from the National Basic Research Program of China (no. 2009CB623602), the National Nature Science Foundation of China (nos 50990065, 51010003, 60906032 and 61177022), the Program for New Century Excellent Talents in University (NCET-10-0400) and Fundamental Research Funds for the Central Universities (2009ZZ0047).

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Authors and Affiliations

  1. Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, PR China

    Zhicai He, Chengmei Zhong, Shijian Su, Miao Xu, Hongbin Wu & Yong Cao

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  1. Zhicai He
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  2. Chengmei Zhong
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  5. Hongbin Wu
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Contributions

H.W., Z.H. and C.Z. conceived the idea and designed the experiments. Z.H. fabricated and characterized the devices. C.Z. carried out the optical calculation. S.S. synthesized the interlayer polymer. H.W. and Y.C. coordinated and directed the study. All authors contributed to manuscript preparation, data analysis and interpretation, and discussed the results.

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Correspondence to Hongbin Wu.

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He, Z., Zhong, C., Su, S. et al. Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure. Nature Photon 6, 591–595 (2012). https://doi.org/10.1038/nphoton.2012.190

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