Skip to main content
SpringerLink
Log in

Constructing vertical phase separation of polymer blends via mixed solvents to enhance their photovoltaic performance

  • Articles
  • Special Issue Organic Photovoltaics
  • Published:
Science China Chemistry Aims and scope Submit manuscript

Abstract

A polymer blend comprising poly(3-hexylthiophene) (P3HT) donor and poly[2,7-(9,9′-octyl-fluorene)-alt-5,5-(4′,7′-di-2-thienyl-5′,6′-bis(hexyloxy)-2′,1′,3′-benzothiadiazole)] (PFDTBT-OC6) acceptor is used as the active layer to fabricate all-polymer solar cells. The blend morphology variance processed with pure and mixed solvents, and the related photovoltaic performance, are investigated in detail. It is found that, due to its low surface energy, a thin P3HT enrichment layer on the top surface of the active layer greatly increases bimolecular recombination and results in S-kinks of the illuminated current density-voltage curves. With the incorporation of p-xylene (a marginal solvent of P3HT) in the blend solution, the P3HT enrichment atop the active layer surface is effectively decreased because the high boiling-point p-xylene suppresses the diffusion of P3HT chains toward the top surface during the film-drying process. The bimolecular recombination was thus improved and the S-kinks of the photovoltaic curves were completely removed. The overall power conversion efficiencies of the devices are strongly boosted (from 0.88% to 1.41%) when chlorobenzene:p-xylene mixed solvent is used to replace pure chlorobenzene.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. He ZC, Zhong CM, Su SJ, Xu M, Wu HB, Cao Y. Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure. Nat Photon, 2012, 6: 591–595

    Google Scholar 

  2. Small CE, Chen S, Subbiah J, Amb CM, Tsang SW, Lai TH, Reynolds JR, So F. High-efficiency inverted dithienogermole-thienopyrrolodione-based polymer solar cells. Nat Photon, 2012, 6: 115–120

    Article  CAS  Google Scholar 

  3. Chen S, Small CE, Amb CM, Subbiah J, Lai TH, Tsang SW, Manders JR, Reynolds JR, So F. Inverted polymer solar cells with reduced interface recombination. Adv Energy Mater, 2012, 2: 1333–1337

    Article  CAS  Google Scholar 

  4. Yang TB, Wang M, Duan CH, Hu XW, Huang L, Peng JB, Huang F, Gong X. Inverted polymer solar cells with 8.4% efficiency by conjugated polyelectrolyte. Energy Environ Sci, 2012, 5: 8208–8214

    Article  CAS  Google Scholar 

  5. Cabanetos C, El LA, Bartelt JA, Douglas JD, Mateker WR, Fréchet JMJ, McGehee MD, Beaujuge PM. Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione polymers direct self-assembly and solar cell performance. J Am Chem Soc, 2013, 135: 4656–4659

    Article  CAS  Google Scholar 

  6. Osaka I, Kakara T, Takemura N, Koganezawa T, Takimiya K. Naphthodithiophene-naphthobisthiadiazole copolymers for solar cells: alkylation drives the polymer backbone flat and promotes efficiency. J Am Chem Soc, 2013, 135: 8834–8837

    Article  CAS  Google Scholar 

  7. Deng YF, Liu J, Wang JT, Liu LH, Li WL, Tian HK, Zhang XJ, Xie ZY, Geng YH, Wang FS. Dithienocarbazole and isoindigo based amorphous low bandgap conjugated polymers for efficient polymer solar cells. Adv Mater, 2014, 26: 471–476

    Article  CAS  Google Scholar 

  8. Stalder R, Mei JG, Subbiah J, Grand C, Estrada LA, So F, Reynolds JR. n-Type conjugated polyisoindigos. Macromolecules, 2011, 44: 6303–6310

    Article  CAS  Google Scholar 

  9. Ahmed E, Ren GQ, Kim FS, Hollenbeck EC, Jenekhe SA. Design of new electron acceptor materials for organic photovoltaics: synthesis, electron transport, photophysics, and photovoltaic properties of oligothiophene-functionalized naphthalene diimides. Chem Mater, 2011, 23: 4563–4577

    Article  CAS  Google Scholar 

  10. Zhou EJ, Cong JZ, Hashimoto K, Tajima K. Control of miscibility and aggregation via the material design and coating process for high-performance polymer blend solar cells. Adv Mater, 2013, 25: 6991–6996

    Article  CAS  Google Scholar 

  11. Mori D, Benten H, Ohkita H, Ito S, Miyake K. Polymer/polymer blend solar cells improved by using high-molecular-weight fluorene-based copolymer as electron acceptor. Acs Appl Mater Interfaces, 2012, 4: 3325–3329

    Article  CAS  Google Scholar 

  12. Cheng P, Ye L, Zhao XG, Hou JH, Li YF, Zhan XW. Binary additives synergistically boost the efficiency of all-polymer solar cells up to 3.45%. Energy Environ Sci, 2014, 7: 1351–1356

    Article  CAS  Google Scholar 

  13. Mori D, Benten H, Okada I, Ohkita H, Ito S. Low-bandgap donor/acceptor polymer blend solar cells with efficiency exceeding 4%. Adv Energy Mater, 2014, 4: 1301006

    Article  Google Scholar 

  14. Yang QQ, Song HY, Gao BR, Wang Y, Fu YY, Yang JW, Xie ZY, Wang LX. High open-circuit voltage polymer/polymer blend solar cells with a polyfluorene copolymer as the electron acceptor. RSC Adv, 2014, 4: 12579–12585

    Article  CAS  Google Scholar 

  15. Qi BY, Wang JZ. Fill factor in organic solar cells. Phys Chem Chem Phys, 2013, 15: 8972–8982

    Article  CAS  Google Scholar 

  16. Tress W, Petrich A, Hummert M, Hein M, Leo K, Riede M. Imbalanced mobilities causing S-shaped IV curves in planar heterojunction organic solar cells. Appl Phys Lett, 2011, 98: 063301

    Article  Google Scholar 

  17. Kumar A, Sista S, Yang Y. Dipole induced anomalous S-shape I–V curves in polymer solar cells. J Appl Phys, 2009, 105: 094512

    Article  Google Scholar 

  18. Uhrich C, Wynands D, Olthof S, Riede MK, Leo K, Sonntag S, Maennig B, Pfeiffer M. Origin of open circuit voltage in planar and bulk heterojunction organic thin-film photovoltaics depending on doped transport layers. J Appl Phys, 2008, 104: 043107

    Article  Google Scholar 

  19. Schulze K, Uhrich C, Schüppel R, Leo K, Pfeiffer M, Brier E, Reinold E, Bäuerle P. Efficient vacuum-deposited organic solar cells based on a new low-bandgap oligothiophene and fullerene C60. Adv Mater, 2006, 18: 2872–2875

    Article  CAS  Google Scholar 

  20. Tress W, Leo K, Riede M. Influence of hole-transport layers and donor materials on open-circuit voltage and shape of I–V curves of organic solar cells. Adv Funct Mater, 2011, 21: 2140–2149

    Article  CAS  Google Scholar 

  21. Gupta D, Mukhopadhyay S, Narayan KS. Fill factor in organic solar cells. Sol Energy Mater Sol Cells, 2010, 94: 1309–1313

    Article  CAS  Google Scholar 

  22. Jin H, Tuomikoski M, Hiltunen J, Kopola P, Maaninen A, Pino F. polymer-electrode interfacial effect on photovoltaic performances in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester based solar cells. J Phys Chem C, 2009, 113: 16807–16810

    Article  CAS  Google Scholar 

  23. Wagenpfahl A, Rauh D, Binder M, Deibel C, Dyakonov V. S-shaped current-voltage characteristics of organic solar devices. Phys Rev B, 2010, 82: 115306

    Article  Google Scholar 

  24. Wang JC, Ren XC, Shi SQ, Leung CW, Chan PKL. Charge accumulation induced S-shape J-V curves in bilayer heterojunction organic solar cells. Org Electron, 2011, 12: 880–885

    Article  CAS  Google Scholar 

  25. Li MG, Wang L, Liu JG, Zhou K, Yu XH, Xing RB, Geng YH, Han YC. Cooperative effects of solvent and polymer acceptor co-additives in P3HT:PDI solar cells: simultaneous optimization in lateral and vertical phase separation. Phys Chem Chem Phys, 2014, 16: 4528–4537

    Article  CAS  Google Scholar 

  26. Sun Y, Liu JG, Ding Y, Han YC. Controlling the surface composition of PCBM in P3HT/PCBM blend films by using mixed solvents with different evaporation rates. Chinese J Polym Sci, 2013, 31: 1029–1037

    Article  CAS  Google Scholar 

  27. Yao Y, Hou JH, Xu Z, Li G, Yang Y. Effect of solvent mixture on the nanoscale phase separation in polymer solar cells. Adv Funct Mater, 2008, 18: 1783–1789

    Article  CAS  Google Scholar 

  28. Park YD, Lee HS, Choi YJ, Kwak D, Cho Jeong H, Lee S, Cho K. Solubility-induced ordered polythiophene precursors for high-performance organic thin-film transistors. Adv Funct Mater, 2009, 19: 1200–1206

    Article  CAS  Google Scholar 

  29. Moule AJ, Meerholz K. Controlling morphology in polymer-fullerene mixtures. Adv Mater, 2008, 20: 240–245

    Article  CAS  Google Scholar 

  30. Li LG, Lu GH, Yang XN. Improving performance of polymer photovoltaic devices using an annealing-free approach via construction of ordered aggregates in solution. J Mater Chem, 2008, 18: 1984–1990

    Article  CAS  Google Scholar 

  31. Owens DK, Wendt RC. Estimation of the surface free energy of polymers. J Appl Polym Sci, 1969, 13: 1741–1747

    Article  CAS  Google Scholar 

  32. Gong X, Tong MH, Brunetti FG, Seo J, Sun YM, Moses D, Wudl Fred, Heeger AJ. Bulk heterojunction solar cells with large open-circuit voltage: electron transfer with small donor-acceptor energy offset. Adv Mater, 2011, 23: 2272–2277

    Article  CAS  Google Scholar 

  33. Chang M, Choi D, Fu BY, Reichmanis E. Solvent based hydrogen bonding: impact on poly(3-hexylthiophene) nanoscale morphology and charge transport characteristics. ACS Nano, 2013, 7: 5402–5413

    Article  CAS  Google Scholar 

  34. McNeill CR, Halls JJM, Wilson R, Whiting GL, Berkebile S, Ramsey MG, Friend RH, Greenham NC. Efficient polythiophene/polyfluorene copolymer bulk heterojunction photovoltaic devices: device physics and annealing effects. Adv Funct Mater, 2008, 18: 2309–2321

    Article  CAS  Google Scholar 

  35. Guo XG, Zhou NJ, Lou SJ, Smith J, Tice DB, Hennek JW, Ortiz RP, Navarrete JTL, Li SY, Strzalka J, Chen LX, Chang RPH, Facchetti A, Marks TJ. Polymer solar cells with enhanced fill factor. Nat Photon, 2013, 7: 825–833

    Article  CAS  Google Scholar 

  36. Rand BP, Burk DP, Forrest SR. Offset energies at organic semiconductor heterojunctions and their influence on the open-circuit voltage of thin-film solar cells. Phys Rev B, 2007, 75: 115327

    Article  Google Scholar 

  37. Liu J, Shi Y, Yang Y. Solvation-induced morphology effects on the performance of polymer-based photovoltaic devices. Adv Funct Mater, 2001, 11: 420–424

    Article  CAS  Google Scholar 

  38. Bartelt JA, Beiley ZM, Hoke ET, Mateker WR, Douglas JD, Collins BA, Tumbleston JR, Graham KR, Amassian A, Ade H, Fréchet JMJ, Toney MF, McGehee MD. The importance of fullerene percolation in the mixed regions of polymer-fullerene bulk heterojunction solar cells. Adv Energy Mater, 2013, 3: 364–374

    Article  CAS  Google Scholar 

  39. Yu W, Xu YM, Li HM, Wang J, Fu GS, Lu WB. Enhanced photon-generated carrier extraction from Si nanostructure under additional infrared light irradiation. Appl Phys Lett, 2013, 102: 201101

    Article  Google Scholar 

  40. Sharenko A, Proctor CM, van der PTS, Henson ZB, Nguyen TQ, Bazan GC. A high-performing solution-processed small molecule:perylene diimide bulk heterojunction solar cell. Adv Mater, 2013, 25: 4403–4406

    Article  CAS  Google Scholar 

  41. Li Z, Gao F, Greenham NC, McNeill CR. Comparison of the operation of polymer/fullerene, polymer/polymer, and polymer/nanocrystal solar cells: a transient photocurrent and photovoltage study. Adv Funct Mater, 2011, 21: 1419–1431

    Article  CAS  Google Scholar 

  42. Jan Anton Koster L, Kemerink M, Wienk MM, Maturová K, Janssen RA. Quantifying bimolecular recombination losses in organic bulk heterojunction solar cells. Adv Mater, 2011, 23: 1670–1674

    Article  Google Scholar 

  43. Clarke TM, Peet J, Nattestad A, Drolet N, Dennler G, Lungenschmied C, Leclerc M, Mozer AJ. Charge carrier mobility, bimolecular recombination and trapping in polycarbazole copolymer:fullerene (PCDTBT:PCBM) bulk heterojunction solar cells. Org Electron, 2012, 13: 2639–2646

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China

    Qingqing Yang, Jiantai Wang, Xiaoqin Zhang, Jun Zhang, Yingying Fu & Zhiyuan Xie

  2. University of Chinese Academy of Sciences, Beijing, 100039, China

    Qingqing Yang, Jiantai Wang, Xiaoqin Zhang & Jun Zhang

Authors
  1. Qingqing Yang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Jiantai Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Xiaoqin Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jun Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Yingying Fu
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Zhiyuan Xie
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Zhiyuan Xie.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yang, Q., Wang, J., Zhang, X. et al. Constructing vertical phase separation of polymer blends via mixed solvents to enhance their photovoltaic performance. Sci. China Chem. 58, 309–316 (2015). https://doi.org/10.1007/s11426-014-5187-7

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11426-014-5187-7

Keywords

Search

Navigation