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Small-molecule solar cells with efficiency over 9%

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Abstract

At present, state-of-the-art single-junction organic photovoltaic devices have power conversion efficiencies of >9% and >8% for polymer- and small-molecule-based devices, respectively. Here, we report a solution-processed organic photovoltaic device based on DRCN7T, which employs an oligothiophene-like small molecule with seven conjugation units as the backbone and 2-(1,1-dicyanomethylene)rhodanine as the terminal unit. With [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as the acceptor, an optimized power conversion efficiency of 9.30% (certified at 8.995%) is achieved. The DRCN7T-based devices have a nearly 100% internal quantum efficiency, which we believe is due to an optimized nanoscale interpenetrating donor/acceptor network (with highly crystalline donor fibrils with diameters of 10 nm, close to the exciton diffusion length in organic materials) and the use of an efficient electron transport layer.

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Figure 1: Molecular design and characterization.
Figure 2: Device performance with structure ITO/PEDOT:PSS/DRCN7T:PC71BM or DERHD7T:PC71BM/PFN/Al.
Figure 3: Morphology of blend films.
Figure 4: GIXD data of the blend films.

References

  1. 1

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

    ADS  Article  Google Scholar 

  2. 2

    Liao, S. H., Jhuo, H. J., Cheng, Y. S. & Chen, S. A. Fullerene derivative-doped zinc oxide nanofilm as the cathode of inverted polymer solar cells with low-bandgap polymer (PTB7-Th) for high performance. Adv. Mater. 25, 4766–4771 (2013).

    Article  Google Scholar 

  3. 3

    You, J. et al. A polymer tandem solar cell with 10.6% power conversion efficiency. Nature Commun. 4, 1446 (2013).

    ADS  Article  Google Scholar 

  4. 4

    Coughlin, J. E., Henson, Z. B., Welch, G. C. & Bazan, G. C. Design and synthesis of molecular donors for solution-processed high-efficiency organic solar cells. Acc. Chem. Res. 47, 257–270 (2013).

    Article  Google Scholar 

  5. 5

    Chen, Y., Wan, X. & Long, G. High performance photovoltaic applications using solution-processed small molecules. Acc. Chem. Res. 46, 2645–2655 (2013).

    Article  Google Scholar 

  6. 6

    Mishra, A. & Bäuerle, P. Small molecule organic semiconductors on the move: promises for future solar energy technology. Angew. Chem. Int. Ed. 51, 2020–2067 (2012).

    Article  Google Scholar 

  7. 7

    Zhou, J. et al. Solution-processed and high-performance organic solar cells using small molecules with a benzodithiophene unit. J. Am. Chem. Soc. 135, 8484–8487 (2013).

    Article  Google Scholar 

  8. 8

    Kyaw, A. K. K. et al. Improved light harvesting and improved efficiency by insertion of an optical spacer (ZnO) in solution-processed small-molecule solar cells. Nano Lett. 13, 3796–3801 (2013).

    ADS  Article  Google Scholar 

  9. 9

    Liu, Y. et al. Solution-processed small-molecule solar cells: breaking the 10% power conversion efficiency. Sci. Rep. 3, 3356 (2013).

    Article  Google Scholar 

  10. 10

    Heliatek. Heliatek consolidates its technology leadership by establishing a new world record for organic solar technology with a cell efficiency of 12%. Available at http://www.heliatek.com/wp-content/uploads/2013/01/130116_PR_Heliatek_achieves_record_cell_effiency_for_OPV.pdf. (January, 2013).

  11. 11

    Steinmann, V. et al. Simple, highly efficient vacuum-processed bulk heterojunction solar cells based on merocyanine dyes. Adv. Energy Mater. 1, 888–893 (2011).

    Article  Google Scholar 

  12. 12

    Sun, Y. et al. Solution-processed small-molecule solar cells with 6.7% efficiency. Nature Mater. 11, 44–48 (2012).

    ADS  Article  Google Scholar 

  13. 13

    Walker, B., Kim, C. & Nguyen, T.-Q. Small molecule solution-processed bulk heterojunction solar cells. Chem. Mater. 23, 470–482 (2010).

    Article  Google Scholar 

  14. 14

    Jorgensen, M., Norrman, K. & Krebs, F. C. Stability/degradation of polymer solar cells. Sol. Energy Mater. Sol. Cells 92, 686–714 (2008).

    Article  Google Scholar 

  15. 15

    Blom, P. W., 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 

  16. 16

    Roncali, J. Molecular bulk heterojunctions: an emerging approach to organic solar cells. Acc. Chem. Res. 42, 1719–1730 (2009).

    Article  Google Scholar 

  17. 17

    Liang, Y. & Yu, L. A new class of semiconducting polymers for bulk heterojunction solar cells with exceptionally high performance. Acc. Chem. Res. 43, 1227–1236 (2010).

    Article  Google Scholar 

  18. 18

    Zhou, H., Yang, L. & You, W. Rational design of high performance conjugated polymers for organic solar cells. Macromolecules 45, 607–632 (2012).

    ADS  Article  Google Scholar 

  19. 19

    Li, Y. Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption. Acc. Chem. Res. 45, 723–733 (2012).

    Article  Google Scholar 

  20. 20

    Lin, Y., Li, Y. & Zhan, X. Small molecule semiconductors for high-efficiency organic photovoltaics. Chem. Soc. Rev. 41, 4245–4272 (2012).

    Article  Google Scholar 

  21. 21

    Brabec, C. J., Heeney, M., McCulloch, I. & Nelson, J. Influence of blend microstructure on bulk heterojunction organic photovoltaic performance. Chem. Soc. Rev. 40, 1185–1199 (2011).

    Article  Google Scholar 

  22. 22

    Liu, F. et al. Characterization of the morphology of solution-processed bulk heterojunction organic photovoltaics. Prog. Polym. Sci. 38, 1990–2052 (2013).

    Article  Google Scholar 

  23. 23

    Chen, L.-M., Xu, Z., Hong, Z. & Yang, Y. Interface investigation and engineering—achieving high performance polymer photovoltaic devices. J. Mater. Chem. 20, 2575–2598 (2010).

    Article  Google Scholar 

  24. 24

    Yip, H.-L. & Jen, A. K. Y. Recent advances in solution-processed interfacial materials for efficient and stable polymer solar cells. Energy Environ. Sci. 5, 5994–6011 (2012).

    Article  Google Scholar 

  25. 25

    He, Z., Wu, H. & Cao, Y. Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol soluble conjugated polymers as electrode buffer layer. Adv. Mater. 26, 1006–1024 (2014).

    ADS  Article  Google Scholar 

  26. 26

    Kyaw, A. K. K. et al. Efficient solution processed small molecule solar cells with inverted structure. Adv. Mater. 25, 2397–2402 (2013).

    Article  Google Scholar 

  27. 27

    Li, X. et al. Dual plasmonic nanostructures for high performance inverted organic solar cells. Adv. Mater. 24, 3046–3052 (2012).

    ADS  Article  Google Scholar 

  28. 28

    Dou, L. et al. 25th anniversary article: A decade of organic/polymeric photovoltaic research. Adv. Mater. 25, 6642–6671 (2013).

    Article  Google Scholar 

  29. 29

    Li, Z. et al. Solution processable rhodanine-based small molecule organic photovoltaic cells with a power conversion efficiency of 6.1%. Adv. Energy Mater. 2, 74–77 (2012).

    ADS  Article  Google Scholar 

  30. 30

    Proctor, C. M., Kuik, M. & Nguyen, T.-Q. Charge carrier recombination in organic solar cells. Prog. Polym. Sci. 38, 1941–1960 (2013).

    Article  Google Scholar 

  31. 31

    Mao, J. et al. Stable dyes containing double acceptors without COOH as anchors for highly efficient dye-sensitized solar cells. Angew. Chem. Int. Ed. 124, 10011–10014 (2012).

    Article  Google Scholar 

  32. 32

    Kuo, M. Y., Chen, H. Y. & Chao, I. Cyanation: providing a three in one advantage for the design of n-type organic field-effect transistors. Chem. Eur. J. 13, 4750–4758 (2007).

    Article  Google Scholar 

  33. 33

    Brédas, J.-L., Beljonne, D., Coropceanu, V. & Cornil, J. Charge-transfer and energy-transfer processes in π-conjugated oligomers and polymers: a molecular picture. Chem. Rev. 104, 4971–5004 (2004).

    Article  Google Scholar 

  34. 34

    Park, S. H. et al. Bulk heterojunction solar cells with internal quantum efficiency approaching 100%. Nature Photon. 3, 297–302 (2009).

    ADS  Article  Google Scholar 

  35. 35

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

    ADS  Article  Google Scholar 

  36. 36

    Peumans, P., Yakimov, A. & Forrest, S. R. Small molecular weight organic thin-film photodetectors and solar cells. J. Appl. Phys. 93, 3693–3723 (2003).

    ADS  Article  Google Scholar 

  37. 37

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

    Article  Google Scholar 

  38. 38

    Long, G. et al. Impact of the electron-transport layer on the performance of solution-processed small-molecule organic solar cells. ChemSusChem 7, 2358–2364 (2014).

    Article  Google Scholar 

  39. 39

    Mandoc, M. M., Veurman, W., Koster, L. J. A., de Boer, B. & Blom, P. W. Origin of the reduced fill factor and photocurrent in MDMO-PPV:PCNEPV all polymer solar cells. Adv. Funct. Mater. 17, 2167–2173 (2007).

    Article  Google Scholar 

  40. 40

    Proctor, C. M., Kim, C., Neher, D. & Nguyen, T.-Q. Nongeminate recombination and charge transport limitations in diketopyrrolopyrrole-based solution-processed small molecule solar cells. Adv. Funct. Mater. 23, 3584–3594 (2013).

    Article  Google Scholar 

  41. 41

    Guerrero, A. et al. Solution-processed small molecule:fullerene bulk-heterojunction solar cells: impedance spectroscopy deduced bulk and interfacial limits to fill-factors. Phys. Chem. Chem. Phys. 15, 16456–16462 (2013).

    Article  Google Scholar 

  42. 42

    Lenes, M., Morana, M., Brabec, C. J. & Blom, P. W. Recombination limited photocurrents in low bandgap polymer/fullerene solar cells. Adv. Funct. Mater. 19, 1106–1111 (2009).

    Article  Google Scholar 

  43. 43

    Mozer, A. J. et al. Charge transport and recombination in bulk heterojunction solar cells studied by the photoinduced charge extraction in linearly increasing voltage technique. Appl. Phys. Lett. 86, 112104 (2005).

    ADS  Article  Google Scholar 

  44. 44

    Li, W. et al. Effect of the fibrillar microstructure on the efficiency of high molecular weight diketopyrrolopyrrole-based polymer solar cells. Adv. Mater. 26, 1565–1570 (2014).

    ADS  Article  Google Scholar 

  45. 45

    Guo, X. G. et al. Polymer solar cells with enhanced fill factors. Nature Photon. 7, 825–833 (2013).

    ADS  Article  Google Scholar 

  46. 46

    Chen, D., Liu, F., Wang, C., Nakahara, A. & Russell, T. P. Bulk heterojunction photovoltaic active layers via bilayer interdiffusion. Nano Lett. 11, 2071–2078 (2011).

    ADS  Article  Google Scholar 

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Acknowledgements

The authors acknowledge financial support from the Ministry of Science and Technology of China (MoST, 2014CB643502 and 2012CB933401), the National Natural Science Foundation of China (NSFC, 51373078) and the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, IRT1257). The morphological characterization of the active layers was supported by the DOE-funded Energy Frontier Research Center on Polymer-Based Materials for Harvesting Solar Energy (DE-SC0001087). Portions of this research were carried out at the Advanced Light Source, Berkeley National Laboratory, which was supported by the DOE, Office of Science and Office of Basic Energy Sciences. The authors also acknowledge Beamline BL14B1 (Shanghai Synchrotron Radiation Facility) for providing beam time.

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Contributions

Y.C., Q.Z. and X.W. proposed and designed the project and Y.C. and X.W. directed the study. Q.Z. and M.L. fabricated and characterized the devices. B.K. synthesized most of the donor materials with help from W.N., Y.Z. and H.Z. F.L. and T.R. performed and analysed the GIXD and RSoXS film characterization. G.K. and M.Z. performed the DFT calculations and the optical simulations. X.C. and Z.L. performed the experiments on refractive index n and extinction coefficient k and photo-CELIV. Z.H., F.H. and Y.C. provided the PFN materials. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Yongsheng Chen.

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A patent (application no. CN2014100099426) has been filed for the materials and devices.

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Zhang, Q., Kan, B., Liu, F. et al. Small-molecule solar cells with efficiency over 9%. Nature Photon 9, 35–41 (2015). https://doi.org/10.1038/nphoton.2014.269

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