The recombination of electrons and holes is a major loss mechanism in photovoltaic devices that controls their performance. We review scientific literature on bimolecular recombination (BR) in bulk heterojunction organic photovoltaic devices to bring forward existing ideas on the origin and nature of BR and highlight both experimental and theoretical work done to quantify its extent. For these systems, Langevin theory fails to explain BR, and recombination dynamics turns out to be dependent on mobility, temperature, electric field, charge carrier concentration, and trapped charges. Relationships among the photocurrent, open-circuit voltage, fill factor, and morphology are discussed. Finally, we highlight the recent emergence of a molecular-level picture of recombination, taking into account the spin and delocalization of charges. Together with the macroscopic picture of recombination, these new insights allow for a comprehensive understanding of BR and provide design principles for future materials and devices.


Article metrics loading...

Loading full text...

Full text loading...


Literature Cited

  1. Brabec C, Gowrisanker S, Halls J, Laird D, Jia S, Williams S. 1.  2010. Polymer-fullerene bulk-heterojunction solar cells. Adv. Mater. 22:3839–56 [Google Scholar]
  2. Dennler G, Scharber MC, Brabec CJ. 2.  2009. Polymer-fullerene bulk-heterojunction solar cells. Adv. Mater. 21:1323–38 [Google Scholar]
  3. Dennler G, Scharber MC, Ameri T, Denk P, Forberich K. 3.  et al. 2008. Design rules for donors in bulk-heterojunction tandem solar cells towards 15% energy-conversion efficiency. Adv. Mater. 20:579–83 [Google Scholar]
  4. Brabec C, Scherf U, Dyakonov V. 4.  2008. Organic Photovoltaics: Materials, Device Physics, and Manufacturing Technologies New York: Wiley [Google Scholar]
  5. Scharber MC, Mühlbacher D, Koppe M, Denk P, Waldauf C. 5.  et al. 2006. Design rules for donors in bulk-heterojunction solar cells: towards 10% energy-conversion efficiency. Adv. Mater. 18:789–94 [Google Scholar]
  6. Li G, Zhu R, Yang Y. 6.  2012. Polymer solar cells. Nat. Photon. 6:153–61 [Google Scholar]
  7. Chen L-M, Hong Z, Li G, Yang Y. 7.  2009. Recent progress in polymer solar cells: manipulation of polymer:fullerene morphology and the formation of efficient inverted polymer solar cells. Adv. Mater. 21:1434–49 [Google Scholar]
  8. Liang Y, Xu Z, Xia J, Tsai S-T, Wu Y. 8.  et al. 2010. For the bright future: bulk heterojunction polymer solar cells with power conversion efficiency of 7.4%. Adv. Mater. 22:E135–38 [Google Scholar]
  9. Credgington D, Hamilton R, Atienzar P, Nelson J, Durrant JR. 9.  2011. Non-geminate recombination as the primary determinant of open-circuit voltage in polythiophene:fullerene blend solar cells: an analysis of the influence of device processing conditions. Adv. Funct. Mater. 21:2744–53 [Google Scholar]
  10. Shuttle CG, Hamilton R, O'Regan BC, Nelson J, Durrant JR. 10.  2010. Charge-density-based analysis of the current–voltage response of polythiophene/fullerene photovoltaic devices. Proc. Natl. Acad. Sci. USA 107:16448–52 [Google Scholar]
  11. Halls JJM, Walsh CA, Greenham NC, Marseglia EA, Friend RH. 11.  et al. 1995. Efficient photodiodes from interpenetrating polymer networks. Nature 376:498–500 [Google Scholar]
  12. Yu G, Gao J, Hummelen JC, Wudl F, Heeger AJ. 12.  1995. Polymer photovoltaic cells: enhanced efficiencies via a network of internal donor-acceptor heterojunctions. Science 270:1789–91 [Google Scholar]
  13. Rao A, Chow PCY, Gélinas S, Schlenker CW, Li C-Z. 13.  et al. 2013. The role of spin in the kinetic control of recombination in organic photovoltaics. Nature 500:435–39 [Google Scholar]
  14. Brédas J-L, Norton JE, Cornil J, Coropceanu V. 14.  2009. Molecular understanding of organic solar cells: the challenges. Acc. Chem. Res. 42:1691–99 [Google Scholar]
  15. Bakulin A, Rao A, Pavelyev V, van Loosdrecht P, Pshenichnikov M. 15.  et al. 2012. The role of driving energy and delocalized states for charge separation in organic semiconductors. Science 335:1340–44 [Google Scholar]
  16. Friend R, Phillips M, Rao A, Wilson M, Li Z, McNeill C. 16.  2012. Excitons and charges at organic semiconductor heterojunctions. Faraday Discuss. 155:339–48 [Google Scholar]
  17. Grancini G, Maiuri M, Fazzi D, Petrozza A, Egelhaaf HJ. 17.  et al. 2013. Hot exciton dissociation in polymer solar cells. Nat. Mater. 12:29–33 [Google Scholar]
  18. Veldman D, Meskers SCJ, Janssen RAJ. 18.  2009. The energy of charge-transfer states in electron donor–acceptor blends: insight into the energy losses in organic solar cells. Adv. Funct. Mater. 19:1939–48 [Google Scholar]
  19. Deibel C, Strobel T, Dyakonov V. 19.  2010. Role of the charge transfer state in organic donor-acceptor solar cells. Adv. Mater. 22:4097–111 [Google Scholar]
  20. Jailaubekov A, Willard AP, Tritsch JR, Chan W-L, Sai N. 20.  et al. 2013. Hot charge-transfer excitons set the time limit for charge separation at donor/acceptor interfaces in organic photovoltaics. Nat. Mater. 12:66–73 [Google Scholar]
  21. Zhu XY, Yang Q, Muntwiler M. 21.  2009. Charge-transfer excitons at organic semiconductor surfaces and interfaces. Acc. Chem. Res. 42:1779–87 [Google Scholar]
  22. McGehee MD. 22.  2009. Organic solar cells: overcoming recombination. Nat. Photon. 3:250–52 [Google Scholar]
  23. Sun Y, Takacs C, Cowan S, Seo J, Gong X. 23.  et al. 2011. Efficient, air-stable bulk heterojunction polymer solar cells using MoOx as the anode interfacial layer. Adv. Mater. 23:2226–30 [Google Scholar]
  24. Vaynzof Y, Kabra D, Zhao L, Ho PKH, Wee ATS, Friend RH. 24.  2010. Improved photoinduced charge carriers separation in organic-inorganic hybrid photovoltaic devices. Appl. Phys. Lett. 97:033309 [Google Scholar]
  25. Liu X, Wen W, Bazan G. 25.  2012. Post-deposition treatment of an arylated-carbazole conjugated polymer for solar cell fabrication. Adv. Mater. 24:4505–10 [Google Scholar]
  26. Seo JH, Gutacker A, Sun Y, Wu H, Huang F. 26.  et al. 2011. Improved high-efficiency organic solar cells via incorporation of a conjugated polyelectrolyte interlayer. J. Am. Chem. Soc. 133:8416–19 [Google Scholar]
  27. He Z, Zhong C, Su S, Xu M, Wu H, Cao Y. 27.  2012. Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure. Nat. Photon. 6:591–95 [Google Scholar]
  28. He Z, Zhong C, Huang X, Wong W-Y, Wu H. 28.  et al. 2011. Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in polymer solar cells. Adv. Mater. 23:4636–43 [Google Scholar]
  29. Etzold F, Howard I, Mauer R, Meister M, Kim T-D. 29.  et al. 2011. Ultrafast exciton dissociation followed by nongeminate charge recombination in PCDTBT:PCBM photovoltaic blends. J. Am. Chem. Soc. 133:9469–79 [Google Scholar]
  30. Bakulin AA, Dimitrov SD, Rao A, Chow PCY, Nielsen CB. 30.  et al. 2013. Charge-transfer state dynamics following hole and electron transfer in organic photovoltaic devices. J. Phys. Chem. Lett. 4:209–15 [Google Scholar]
  31. Jamieson FC, Domingo EB, McCarthy-Ward T, Heeney M, Stingelin N, Durrant JR. 31.  2012. Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells. Chem. Sci. 3:485–92 [Google Scholar]
  32. Dimitrov S, Bakulin A, Nielsen C, Schroeder B, Du J. 32.  et al. 2012. On the energetic dependence of charge separation in low-band-gap polymer/fullerene blends. J. Am. Chem. Soc. 134:18189–92 [Google Scholar]
  33. Clarke TM, Durrant JR. 33.  2010. Charge photogeneration in organic solar cells. Chem. Rev. 110:6736–67 [Google Scholar]
  34. Ohkita H, Cook S, Astuti Y, Duffy W, Tierney S. 34.  et al. 2008. Charge carrier formation in polythiophene/fullerene blend films studied by transient absorption spectroscopy. J. Am. Chem. Soc. 130:3030–42 [Google Scholar]
  35. Park SH, Roy A, Beaupre S, Cho S, Coates N. 35.  et al. 2009. Bulk heterojunction solar cells with internal quantum efficiency approaching 100%. Nat. Photon. 3:297–302 [Google Scholar]
  36. Price S, Stuart A, Yang L, Zhou H, You W. 36.  2011. Fluorine substituted conjugated polymer of medium band gap yields 7% efficiency in polymer-fullerene solar cells. J. Am. Chem. Soc. 133:4625–31 [Google Scholar]
  37. Credgington D, Durrant JR. 37.  2012. Insights from transient optoelectronic analyses on the open-circuit voltage of organic solar cells. J. Phys. Chem. Lett. 3:1465–78 [Google Scholar]
  38. Hoke ET, Sachs-Quintana IT, Lloyd MT, Kauvar I, Mateker WR. 38.  et al. 2012. The role of electron affinity in determining whether fullerenes catalyze or inhibit photooxidation of polymers for solar cells. Adv. Energy Mater. 2:1351–57 [Google Scholar]
  39. Mayer AC, Michael FT, Shawn RS, Jonathan R, Christoph JB. 39.  et al. 2009. Bimolecular crystals of fullerenes in conjugated polymers and the implications of molecular mixing for solar cells. Adv. Funct. Mater. 19:1173–79 [Google Scholar]
  40. Cates NC, Gysel R, Beiley Z, Miller CE, Toney MF. 40.  et al. 2009. Tuning the properties of polymer bulk heterojunction solar cells by adjusting fullerene size to control intercalation. Nano Lett. 9:4153–57 [Google Scholar]
  41. Liu F, Gu Y, Jung JW, Jo WH, Russell TP. 41.  2012. On the morphology of polymer-based photovoltaics. J. Polymer Sci. B 50:1018–44 [Google Scholar]
  42. Hammond MR, Kline RJ, Herzing AA, Richter LJ, Germack DS. 42.  et al. 2011. Molecular order in high-efficiency polymer/fullerene bulk heterojunction solar cells. ACS Nano 5:8248–57 [Google Scholar]
  43. Credgington D, Durrant JR. 43.  2012. Insights from transient optoelectronic analyses on the open-circuit voltage of organic solar cells. J. Phys. Chem. Lett. 3:1465–78 [Google Scholar]
  44. Koster LJA, Kemerink M, Wienk MM, Maturová K, Janssen RAJ. 44.  2011. Quantifying bimolecular recombination losses in organic bulk heterojunction solar cells. Adv. Mater. 23:1670–74 [Google Scholar]
  45. Shockley W, Queisser HJ. 45.  1961. Detailed balance limit of efficiency of p-n junction solar cells. J. Appl. Phys. 32:510–19 [Google Scholar]
  46. Miller OD, Yablonovitch E, Kurtz SR. 46.  2012. Strong internal and external luminescence as solar cells approach the Shockley-Queisser limit. IEEE J. Photovolt. 2:303–11 [Google Scholar]
  47. Giebink NC, Wiederrecht GP, Wasielewski MR, Forrest SR. 47.  2010. Ideal diode equation for organic heterojunctions. I. Derivation and application. Phys. Rev. B 82:155305 [Google Scholar]
  48. Giebink NC, Lassiter BE, Wiederrecht GP, Wasielewski MR, Forrest SR. 48.  2010. Ideal diode equation for organic heterojunctions. II. The role of polaron pair recombination. Phys. Rev. B 82:155306 [Google Scholar]
  49. Koster LJA, Shaheen SE, Hummelen JC. 49.  2012. Pathways to a new efficiency regime for organic solar cells. Adv. Energy Mater. 2:1246–53 [Google Scholar]
  50. Rau U. 50.  2007. Reciprocity relation between photovoltaic quantum efficiency and electroluminescent emission of solar cells. Phys. Rev. B 76:085303 [Google Scholar]
  51. Vandewal K, Tvingstedt K, Gadisa A, Inganas O, Manca J. 51.  2009. On the origin of the open-circuit voltage of polymer-fullerene solar cells. Nat. Mater. 8:904–9 [Google Scholar]
  52. Schiff EA. 52.  1995. Diffusion-controlled bimolecular recombination of electrons and holes in a-Si:H. J. Non-Cryst. Solids 190:1–8 [Google Scholar]
  53. Jackson WB. 53.  1989. Role of bimolecular recombination in picosecond photoinduced absorption of hydrogenated amorphous silicon. Philos. Mag. Lett. 60:277–82 [Google Scholar]
  54. Langevin P. 54.  2013. Recombinaison et mobilites des ions dans les gaz. Ann. Chim. Phys. 28:433–530 [Google Scholar]
  55. Smoluchowski MV. 55.  1917. Versuch einer mathematischen Theorie der Koagulationskinetik kolloider Loeschungen. Z. Phys. Chem. 92:129 [Google Scholar]
  56. Debye P. 56.  1942. Reaction rates in ionic solution. J. Electrochem. Soc. 82:265–72 [Google Scholar]
  57. Kepler RG, Coppage FN. 57.  1966. Generation and recombination of holes and electrons in anthracene. Phys. Rev. 151:610–14 [Google Scholar]
  58. Silver M, Sharma R. 58.  1967. Carrier generation and recombination in anthracene. J. Chem. Phys. 46:692–96 [Google Scholar]
  59. Karl N, Sommer G. 59.  1971. Field dependent losses of electrons and holes by bimolecular volume recombination in the excitation layer of anthracene single crystals studied by drift current pulses. Phys. Status Solidi A 6:231–41 [Google Scholar]
  60. Braun CL. 60.  1984. Electric field assisted dissociation of charge transfer states as a mechanism of photocarrier production. J. Chem. Phys. 80:4157–61 [Google Scholar]
  61. Adriaenssens GJ, Arkhipov VI. 61.  1997. Non-Langevin recombination in disordered materials with random distributions. Solid State Commun. 103:541–43 [Google Scholar]
  62. Arkhipov VI, Adriaenssens GJ. 62.  1997. Kinetics of low temperature charge carrier recombination. J. Phys. Condens. Matter 9:6869–76 [Google Scholar]
  63. Nelson J. 63.  2003. Diffusion-limited recombination in polymer-fullerene blends and its influence on photocurrent collection. Phys. Rev. B 67:155209 [Google Scholar]
  64. Scher H, Montroll E. 64.  1975. Anomalous transit-time dispersion in amorphous solids. Phys. Rev. B 12:2455–77 [Google Scholar]
  65. Schmidlin F. 65.  1977. Theory of trap-controlled transient photoconduction. Phys. Rev. B 16:2362–85 [Google Scholar]
  66. Koster LJA, Mihailetchi VD, Blom PWM. 66.  2006. Bimolecular recombination in polymer/fullerene bulk heterojunction solar cells. Appl. Phys. Lett. 88:052104 [Google Scholar]
  67. Groves C, Greenham NC. 67.  2008. Bimolecular recombination in polymer electronic devices. Phys. Rev. B 78:155205 [Google Scholar]
  68. Mandoc MM, Kooistra FB, Hummelen JC, Boer BD, Blom PWM. 68.  2007. Effect of traps on the performance of bulk heterojunction organic solar cells. Appl. Phys. Lett. 91:263505 [Google Scholar]
  69. Shockley W, Read WT Jr. 69.  1952. Statistics of the recombination of holes and electrons. Phys. Rev. 87:835–42 [Google Scholar]
  70. Szmytkowski J. 70.  2009. Analysis of the image force effects on the recombination at the donor-acceptor interface in organic bulk heterojunction solar cells. Chem. Phys. Lett. 470:123–25 [Google Scholar]
  71. Scott JC, Malliaras GG. 71.  1999. Charge injection and recombination at the metal–organic interface. Chem. Phys. Lett. 299:115–19 [Google Scholar]
  72. Collins FC, Kimball GE. 72.  1949. Diffusion controlled reaction rates. J. Colloid Sci. 4:425–37 [Google Scholar]
  73. Hilczer M, Tachiya M. 73.  2010. Unified theory of geminate and bulk electron-hole recombination in organic solar cells. J. Phys. Chem. C 114:6808–13 [Google Scholar]
  74. Pivrikas A, Juška G, Mozer AJ, Scharber M, Arlauskas K. 74.  et al. 2005. Bimolecular recombination coefficient as a sensitive testing parameter for low-mobility solar-cell materials. Phys. Rev. Lett. 94:176806 [Google Scholar]
  75. Juška G, Genevičius K, Sliaužys G, Nekrašas N, Österbacka R. 75.  2008. Double injection in organic bulk heterojunction. J. Non-Cryst. Solids 354:2858–61 [Google Scholar]
  76. Juška G, Genevičius K, Nekrašas N, Sliaužys G, Österbacka R. 76.  2009. Two dimensional Langevin recombination in regioregular poly(3-hexylthiophene). Appl. Phys. Lett. 95:013303 [Google Scholar]
  77. Greenham NC, Bobbert PA. 77.  2003. Two-dimensional electron-hole capture in a disordered hopping system. Phys. Rev. B 68:245301 [Google Scholar]
  78. Pivrikas A, Sariciftci NS, Juška G, Österbacka R. 78.  2007. A review of charge transport and recombination in polymer/fullerene organic solar cells. Prog. Photovolt. 15:677–96 [Google Scholar]
  79. Shuttle CG, O'Regan B, Ballantyne AM, Nelson J, Bradley DDC. 79.  et al. 2008. Experimental determination of the rate law for charge carrier decay in a polythiophene:fullerene solar cell. Appl. Phys. Lett. 92:093311 [Google Scholar]
  80. Shuttle CG, O'Regan B, Ballantyne AM, Nelson J, Bradley DDC, Durrant JR. 80.  2008. Bimolecular recombination losses in polythiophene:fullerene solar cells. Phys. Rev. B 78:113201 [Google Scholar]
  81. Shuttle CG, Maurano A, Hamilton R, O'Regan B, Mello JCD, Durrant JR. 81.  2008. Charge extraction analysis of charge carrier densities in a polythiophene/fullerene solar cell: analysis of the origin of the device dark current. Appl. Phys. Lett. 93:183501 [Google Scholar]
  82. Hwang I, McNeill CR, Greenham NC. 82.  2009. Drift-diffusion modeling of photocurrent transients in bulk heterojunction solar cells. J. Appl. Phys. 106:094506 [Google Scholar]
  83. Li Z, Lakhwani G, Greenham NC, McNeill CR. 83.  2013. Voltage-dependent photocurrent transients of PTB7:PC70BM solar cells: experiment and numerical simulation. J. Appl. Phys. 114:034502 [Google Scholar]
  84. Street RA. 84.  2011. Localized state distribution and its effect on recombination in organic solar cells. Phys. Rev. B 84:075208 [Google Scholar]
  85. Cowan SR, Street RA, Cho S, Heeger AJ. 85.  2011. Transient photoconductivity in polymer bulk heterojunction solar cells: competition between sweep-out and recombination. Phys. Rev. B 83:035205 [Google Scholar]
  86. Cowan SR, Leong WL, Banerji N, Dennler G, Heeger AJ. 86.  2011. Identifying a threshold impurity level for organic solar cells: enhanced first-order recombination via well-defined PC84BM traps in organic bulk heterojunction solar cells. Adv. Funct. Mater. 21:3083–92 [Google Scholar]
  87. Deibel C, Baumann A, Dyakonov V. 87.  2008. Polaron recombination in pristine and annealed bulk heterojunction solar cells. Appl. Phys. Lett. 93:163303 [Google Scholar]
  88. Deibel C, Wagenpfahl A, Dyakonov V. 88.  2009. Origin of reduced polaron recombination in organic semiconductor devices. Phys. Rev. B 80:075203 [Google Scholar]
  89. Juška G, Arlauskas K, Stuchlik J, Österbacka R. 89.  2006. Non-Langevin bimolecular recombination in low-mobility materials. J. Non-Cryst. Solids 352:1167–71 [Google Scholar]
  90. Coehoorn R, Pasveer W, Bobbert P, Michels M. 90.  2005. Charge-carrier concentration dependence of the hopping mobility in organic materials with Gaussian disorder. Phys. Rev. B 72:155206 [Google Scholar]
  91. Bouhassoune M, van Mensfoort SLM, Bobbert PA, Coehoorn R. 91.  2009. Carrier-density and field-dependent charge-carrier mobility in organic semiconductors with correlated Gaussian disorder. Org. Electron. 10:437–45 [Google Scholar]
  92. Pasveer WF, Cottaar J, Tanase C, Coehoorn R, Bobbert PA. 92.  et al. 2005. Unified description of charge-carrier mobilities in disordered semiconducting polymers. Phys. Rev. Lett. 94:206601 [Google Scholar]
  93. Shuttle CG, Hamilton R, Nelson J, O'Regan BC, Durrant JR. 93.  2010. Measurement of charge-density dependence of carrier mobility in an organic semiconductor blend. Adv. Funct. Mater. 20:698–702 [Google Scholar]
  94. Rauh D, Deibel C, Dyakonov V. 94.  2012. Charge density dependent nongeminate recombination in organic bulk heterojunction solar cells. Adv. Funct. Mater. 22:3371–77 [Google Scholar]
  95. Street RA, Schoendorf M, Roy A, Lee JH. 95.  2010. Interface state recombination in organic solar cells. Phys. Rev. B 81:205307 [Google Scholar]
  96. Deibel C, Wagenpfahl A. 96.  2010. Comment on “Interface state recombination in organic solar cells.”. Phys. Rev. B 82:207301 [Google Scholar]
  97. Street RA. 97.  2010. Reply to “Comment on ‘Interface state recombination in organic solar cells.’”. Phys. Rev. B 82:207302 [Google Scholar]
  98. Kirchartz T, Nelson J. 98.  2012. Meaning of reaction orders in polymer:fullerene solar cells. Phys. Rev. B 86:165201 [Google Scholar]
  99. Deibel C, Rauh D, Foertig A. 99.  2013. Order of decay of mobile charge carriers in P3HT:PCBM solar cells. Appl. Phys. Lett. 103:043307 [Google Scholar]
  100. Lenes M, Morana M, Brabec CJ, Blom PWM. 100.  2009. Recombination-limited photocurrents in low bandgap polymer/fullerene solar cells. Adv. Funct. Mater. 19:1106–11 [Google Scholar]
  101. Goodman AM, Rose A. 101.  1971. Double extraction of uniformly generated electron-hole pairs from insulators with noninjecting contacts. J. Appl. Phys. 42:2823–30 [Google Scholar]
  102. Mihailetchi VD, Wildeman J, Blom PWM. 102.  2005. Space-charge limited photocurrent. Phys. Rev. Lett. 94:126602 [Google Scholar]
  103. Tessler N, Rappaport N. 103.  2004. Excitation density dependence of photocurrent efficiency in low mobility semiconductors. J. Appl. Phys. 96:1083–87 [Google Scholar]
  104. Rappaport N, Solomesch O, Tessler N. 104.  2005. The interplay between space charge and recombination in conjugated polymer/molecule photocells. J. Appl. Phys. 98:033714 [Google Scholar]
  105. Kirchartz T, Pieters BE, Kirkpatrick J, Rau U, Nelson J. 105.  2011. Recombination via tail states in polythiophene:fullerene solar cells. Phys. Rev. B 83:115209 [Google Scholar]
  106. Albrecht U, Bässler H. 106.  1995. Langevin-type charge carrier recombination in a disordered hopping system. Phys. Status Solidi B 191:455–59 [Google Scholar]
  107. Bartelt JA, Beiley ZM, Hoke ET, Mateker WR, Douglas JD. 107.  et al. 2013. The importance of fullerene percolation in the mixed regions of polymer-fullerene bulk heterojunction solar cells. Adv. Energy Mater. 3:364–74 [Google Scholar]
  108. Yang X, Wang RZ, Wang YC, Sheng CX, Li H. 108.  et al. 2013. Long lived photoexcitation dynamics in π-conjugated polymer and fullerene blended films. Org. Electron. 14:2058–64 [Google Scholar]
  109. Nenashev AV, Jansson F, Baranovskii SD, Österbacka R, Dvurechenskii AV, Gebhard F. 109.  2010. Role of diffusion in two-dimensional bimolecular recombination. Appl. Phys. Lett. 96:213304 [Google Scholar]
  110. Maturová K, van Bavel SS, Wienk MM, Janssen RAJ, Kemerink M. 110.  2009. Morphological device model for organic bulk heterojunction solar cells. Nano Lett. 9:3032–37 [Google Scholar]
  111. Street RA, Krakaris A, Cowan SR. 111.  2012. Recombination through different types of localized states in organic solar cells. Adv. Funct. Mater. 22:4608–19 [Google Scholar]
  112. Yang XN, Loos J, Veenstra SC, Verhees WJH, Wienk MM. 112.  et al. 2005. Nanoscale morphology of high-performance polymer solar cells. Nano Lett. 5:579–83 [Google Scholar]
  113. Armin A, Juška G, Philippa BW, Burn PL, Meredith P. 113.  et al. 2013. Doping-induced screening of the built-in-field in organic solar cells: effect on charge transport and recombination. Adv. Energy Mater. 3:321–27 [Google Scholar]
  114. Lee JK, Ma WL, Brabec CJ, Yuen J, Moon JS. 114.  et al. 2008. Processing additives for improved efficiency from bulk heterojunction solar cells. J. Am. Chem. Soc. 130:3619–23 [Google Scholar]
  115. Albrecht S, Schindler W, Kurpiers J, Kniepert J, Blakesley JC. 115.  et al. 2012. On the field dependence of free charge carrier generation and recombination in blends of PCPDTBT/PC70BM: influence of solvent additives. J. Phys. Chem. Lett. 3:640–45 [Google Scholar]
  116. Peet J, Kim JY, Coates NE, Ma WL, Moses D. 116.  et al. 2007. Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols. Nat. Mater. 6:497–500 [Google Scholar]
  117. Westenhoff S, Howard IA, Hodgkiss JM, Kirov KR, Bronstein HA. 117.  et al. 2008. Charge recombination in organic photovoltaic devices with high open-circuit voltages. J. Am. Chem. Soc. 130:13653–58 [Google Scholar]
  118. Sánchez-Díaz A, Izquierdo M, Filippone S, Martin N, Palomares E. 118.  2010. The origin of the high voltage in DPM12/P3HT organic solar cells. Adv. Funct. Mater. 20:2695–700 [Google Scholar]
  119. Massip S, Oberhumer PM, Tu G, Albert-Seifried S, Huck WTS. 119.  et al. 2011. Influence of side chains on geminate and bimolecular recombination in organic solar cells. J. Phys. Chem. C 115:25046–55 [Google Scholar]
  120. Proctor CM, Kim C, Neher D, Nguyen T-Q. 120.  2013. Nongeminate recombination and charge transport limitations in diketopyrrolopyrrole-based solution-processed small molecule solar cells. Adv. Funct. Mater. 23:3584–94 [Google Scholar]
  121. Maurano A, Hamilton R, Shuttle CG, Ballantyne AM, Nelson J. 121.  et al. 2010. Recombination dynamics as a key determinant of open circuit voltage in organic bulk heterojunction solar cells: a comparison of four different donor polymers. Adv. Mater. 22:4987–92 [Google Scholar]
  122. Li W, Hendriks KH, Roelofs WSC, Kim Y, Wienk MM, Janssen RAJ. 122.  2013. Efficient small bandgap polymer solar cells with high fill factors for 300 nm thick films. Adv. Mater. 25:3182–86 [Google Scholar]
  123. Kyaw AKK, Wang DH, Gupta V, Leong WL, Ke L. 123.  et al. 2013. Intensity dependence of current-voltage characteristics and recombination in high-efficiency solution-processed small-molecule solar cells. ACS Nano 7:4569–77 [Google Scholar]
  124. Howard IA, Laquai F, Keivanidis PE, Friend RH, Greenham NC. 124.  2009. Perylene tetracarboxydiimide as an electron acceptor in organic solar cells: a study of charge generation and recombination. J. Phys. Chem. C 113:21225–32 [Google Scholar]
  125. Di Nuzzo D, Wetzelaer G-JAH, Bouwer RKM, Gevaerts VS, Meskers SCJ. 125.  et al. 2013. Simultaneous open-circuit voltage enhancement and short-circuit current loss in polymer:fullerene solar cells correlated by reduced quantum efficiency for photoinduced electron transfer. Adv. Energy Mater. 3:85–94 [Google Scholar]
  126. Nicolai HT, Kuik M, Wetzelaer GAH, Boer BD, Campbell C. 126.  et al. 2012. Unification of trap-limited electron transport in semiconducting polymers. Nat. Mater. 11:882–87 [Google Scholar]
  127. Kuik M, Koster LJA, Wetzelaer GAH, Blom PWM. 127.  2011. Trap-assisted recombination in disordered organic semiconductors. Phys. Rev. Lett. 107:256805 [Google Scholar]
  128. Chen LM, Xu Z, Hong Z, Yang Y. 128.  2010. Interface investigation and engineering: achieving high performance polymer photovoltaic devices. J. Mater. Chem. 20:2575–98 [Google Scholar]
  129. Graetzel M, Janssen R, Mitzi D, Sargent E. 129.  2012. Materials interface engineering for solution-processed photovoltaics. Nature 488:304–12 [Google Scholar]
  130. Kumar A, Lakhwani G, Elmalem E, Huck WTS, Rao A. 130.  et al. 2014. Interface limited charge extraction and recombination in organic photovoltaics. Submitted manuscript
  131. Wallikewitz BH, Kabra D, Gelinas S, Friend RH. 131.  2012. Triplet dynamics in fluorescent polymer light-emitting diodes. Phys. Rev. B 85:045209 [Google Scholar]
  132. Kabra D, Lu L, Song M, Snaith H, Friend R. 132.  2010. Efficient single-layer polymer light-emitting diodes. Adv. Mater. 22:3194–98 [Google Scholar]
  133. Köhler A, Wilson JS, Friend RH. 133.  2002. Fluorescence and phosphorescence in organic materials. Adv. Mater. 14:701–7 [Google Scholar]
  134. Friend RH, Gymer RW, Holmes AB, Burroughes JH, Marks RN. 134.  et al. 1999. Electroluminescence in conjugated polymers. Nature 397:121–28 [Google Scholar]
  135. Köhler A, Bässler H. 135.  2009. Triplet states in organic semiconductors. Mater. Sci. Eng. R 66:71–109 [Google Scholar]
  136. Uoyama H, Goushi K, Shizu K, Nomura H, Adachi C. 136.  2012. Highly efficient organic light-emitting diodes from delayed fluorescence. Nature 492:234–38 [Google Scholar]
  137. Goushi K, Yoshida K, Sato K, Adachi C. 137.  2012. Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion. Nat. Photon. 6:253–58 [Google Scholar]
  138. Segal M, Singh M, Rivoire K, Difley S, Van Voorhis T, Baldo MA. 138.  2007. Extrafluorescent electroluminescence in organic light-emitting devices. Nat. Mater. 6:374–78 [Google Scholar]
  139. Baldo MA, O'Brien DF, You Y, Shoustikov A, Sibley S. 139.  et al. 1998. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395:151–54 [Google Scholar]

Data & Media loading...

  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error