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Colloidal quantum dot solids for solution-processed solar cells


Solution-processed photovoltaic technologies represent a promising way to reduce the cost and increase the efficiency of solar energy harvesting. Among these, colloidal semiconductor quantum dot photovoltaics have the advantage of a spectrally tuneable infrared bandgap, which enables use in multi-junction cells, as well as the benefit of generating and harvesting multiple charge carrier pairs per absorbed photon. Here we review recent progress in colloidal quantum dot photovoltaics, focusing on three fronts. First, we examine strategies to manage the abundant surfaces of quantum dots, strategies that have led to progress in the removal of electronic trap states. Second, we consider new device architectures that have improved device performance to certified efficiencies of 10.6%. Third, we focus on progress in solution-phase chemical processing, such as spray-coating and centrifugal casting, which has led to the demonstration of manufacturing-ready process technologies.

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Figure 1: Advantages of CQD solids.
Figure 2: Advances in purifying the bandgap of CQD solids.
Figure 3: Band edge control via ligands and stoichiometry.
Figure 4: Advanced materials processing techniques for the scalable manufacturing of CQD solids.


  1. 1

    Masson, G. et al. Global Market Outlook for Photovoltaics until 2016 (EPIA, 2012).

    Google Scholar 

  2. 2

    Best Research Cell Efficiencies (NREL, accessed on 11 January 2016);

  3. 3

    Choi, H., Ko, J., Kim, Y. & Jeong, S. Steric-hindrance-driven shape transistion in PbS quantum dots: understanding size-dependent stability. J. Am. Chem. Soc. 135, 5278–5281 (2013).

    Article  Google Scholar 

  4. 4

    Smith, D. K., Luther, J. M., Semonin, O. E., Nozik, A. J. & Beard, M. C. Tuning the synthesis of ternary lead chalcogenide quantum dots by balancing precursor reactivity. ACS Nano 5, 183–190 (2011).

    Article  Google Scholar 

  5. 5

    Moreels, I. et al. Composition and size-dependent extinction coefficient of colloidal PbSe quantum dots. Chem. Mater. 19, 6101–6106 (2007).

    Article  Google Scholar 

  6. 6

    Hwang, G. W. et al. Identifying and eliminating emissive sub-bandgap states in thin films of PbS nanocrystals. Adv. Mater. 27, 4481–4486 (2015).

    Article  Google Scholar 

  7. 7

    Kim, D., Kim, D., Lee, J. & Grossman, J. C. Impact of stoichiometry on the electronic structure of PbS quantum dots. Phys. Rev. Lett. 110, 196802 (2013). This paper demonstrates the impact of quantum dots' stoichiometry on the electronic structure indicating how precise control over the stoichiometry in the quantum dots will play an important role in improving the performance of optoelectronic devices.

    Article  Google Scholar 

  8. 8

    Gai, Y., Peng, H. & Li, J., Electronic properties of nonstoichiometric PbSe quantum dots from first principles. J. Phys. Chem. C 113, 21506–21511 (2009).

    Article  Google Scholar 

  9. 9

    Zhang, M. et al. Charge percolation pathways guided by defects in quantum dot solids. Nano Lett. 15, 3249–3253 (2015).

    Article  Google Scholar 

  10. 10

    Talapin, D. V. & Murray, C. B. PbSe nanocrystal solids for n- and p-channel thin film field-effect transistors. Science 310, 86–89 (2005).

    Article  Google Scholar 

  11. 11

    Bozyigt, D., Volk, S., Yarema, O. & Wood, V. Quantification of deep traps in nanocrystal solids, their electronic properties, and their influence on device behavior. Nano Lett. 13, 5284–5288 (2013).

    Article  Google Scholar 

  12. 12

    Zhitomirsky, D. et al. Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime. Nature Commun. 5, 3803 (2013).

    Article  Google Scholar 

  13. 13

    Bozyigit, D., Lin, W. M. M., Yazdani, N., Yarema, O. & Wood, V. A quantitative model for charge carrier transport, trapping and recombination in nanocrystal-based solar cells. Nature Commun. 6, 6180 (2014). This paper provides insight into charge transport in different nanocrystal solids and device architectures essential to understanding the design guidelines for engineering high-performance nanocrystal-based devices.

    Article  Google Scholar 

  14. 14

    Yoon, W. et al. Enhanced open-circuit voltage of PbS nanocrystal quantum dot solar cells. Sci. Rep. 3, 2225 (2013).

    Article  Google Scholar 

  15. 15

    Zhitomirsky, D., Voznyy, O., Hoogland, S. & Sargent, E. H. Measuring charge carrier diffusion in coupled colloidal quantum dot solids. ACS Nano 6, 5282–5290 (2013).

    Article  Google Scholar 

  16. 16

    Diaconescu, B., Padilha, L. A., Nagpal, P., Swartzentruber, B. S. & Klimov, V. I. Measurement of electronic states of PbS nanocrystal quantum dots using scanning tunneling spectroscopy: the role of parity selection rules in optical absorption. Phys. Rev. Lett. 110, 127406 (2013).

    Article  Google Scholar 

  17. 17

    Nagpal, P. & Klimov, V. I. Role of mid-gap states in charge transport and photoconductivity in semiconductor nanocrystal films. Nature Commun. 2, 486 (2011).

    Article  Google Scholar 

  18. 18

    Bozyigit, D., Jakob, M., Yarema, O. & Wood, V. Deep level transient spectroscopy (DLTS) on colloidal-synthesized nanocrystal solids. ACS Appl. Mater. Interfaces 5, 2915–2919 (2013).

    Article  Google Scholar 

  19. 19

    Oh, S. J. et al. Stochiometric control of lead chalcogenide nanocrystal solids to enhance their electronic and optoelectronic device performance. ACS Nano 7, 2413–2421 (2013).

    Article  Google Scholar 

  20. 20

    Allgaier, R. S. & Scanlon, W. W. Mobility of electrons and holes in PbS, PbSe and PbTe between room temperature and 4.2 K. Phys. Rev. 111, 1029–1037 (1958).

    Article  Google Scholar 

  21. 21

    Goodwin, E. D. et al. The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films. Chem. Phys. (in the press).

  22. 22

    Bae, W. K. et al. Highly effective surface passivation of PbSe quantum dots through reaction with molecular chlorine. J. Am. Chem. Soc. 134, 20160–20168 (2012).

    Article  Google Scholar 

  23. 23

    Lan, X. et al. Passivation using molecular halides increases quantum dot solar cell performance. Adv. Mater. 28, 299–304 (2016).

    Article  Google Scholar 

  24. 24

    Debnath, R. et al. Ambient-processed colloidal quantum dot solar cells via individual pre-encapsulation of nanoparticles. J. Am. Chem. Soc. 132, 5952–5953 (2010).

    Article  Google Scholar 

  25. 25

    Zhang, J. et al. PbSe quantum dot solar cells with more than 6% efficiency fabricated in ambient atmosphere. Nano Lett. 14, 6010–6015 (2014).

    Article  Google Scholar 

  26. 26

    Ip, A. H. et al. Hybrid passivated colloidal quantum dot solids. Nature Nanotech. 7, 577–582 (2012). This study reports the use of a multiple-liganding strategy that was more effective than a single-ligand approach in eliminating midgap trap states.

    Article  Google Scholar 

  27. 27

    Thon, S. M. et al. Role of bond adaptability in the passivation of colloidal quantum dot solids. ACS Nano 7, 7680–7688 (2013).

    Article  Google Scholar 

  28. 28

    Tang, J. et al. Colloidal-quantum-dot photovoltaics using atomic-ligand passivation. Nature Mater. 10, 765–772 (2011).

    Article  Google Scholar 

  29. 29

    Ning, Z. et al. All-inorganic colloidal quantum dot photovoltaics employing solution-phase-halide passivation. Adv. Mater. 24, 6295–6299 (2012).

    Article  Google Scholar 

  30. 30

    Niu, G. et al. Inorganic halogen ligands in quantum dots: I, Br, Cl and film fabrication through electrophoretic deposition. Phys. Chem. Chem. Phys. 15, 19595–19560 (2013).

    Article  Google Scholar 

  31. 31

    Zhang, H., Jang, J., Liu, W. & Talapin, D. V. Colloidal nanocrystals with inorganic halide, pseudohalide, and halometallate ligands. ACS Nano 8, 7359–7369 (2014).

    Article  Google Scholar 

  32. 32

    Dirin, D. N. et al. Lead halide perovskites and other metal halide complexes as inorganic capping ligands for colloidal nanocrystals. J. Am. Chem. Soc. 136, 6550–6553 (2014).

    Article  Google Scholar 

  33. 33

    Woo, J. Y. et al. Ultrastable PbSe nanocrystal quantum dots via in situ formation of atomically thin halide layers on PbSe(100). J. Am. Chem. Soc. 136, 8883–8886 (2014).

    Article  Google Scholar 

  34. 34

    Crisp, R. W. et al. Nanocrystal grain growth and device architecture for high-efficient CdTe ink-based photovoltaics. ACS Nano 8, 9063–9072 (2014).

    Article  Google Scholar 

  35. 35

    Goodwin, E. D. et al. Effects of post-synthesis processing on CdSe nanocrystals and their solids: correlation between surface chemistry and optoelectronic properties. J. Phys. Chem. C 118, 27097–27105 (2014).

    Article  Google Scholar 

  36. 36

    Greaney, M. J. et al. Controlling the trap state landscape of colloidal CdSe nanocrystals with cadmium halide ligands. Chem. Mater. 27, 744–756 (2015).

    Article  Google Scholar 

  37. 37

    Brown, P. R. et al. Energy level modification in lead sulfide quantum dot thin films through ligand exchange. ACS Nano 8, 5863–5872 (2014). This paper demonstrates that the absolute energy level of CQDs is critically dependent on surface chemistry. It represents an adjustable parameter in the optimization of CQD-based optoelectronic devices.

    Article  Google Scholar 

  38. 38

    Soreni-Harani, M. et al. Tuning energetic levels in nanocrystal quantum dots through surface manipulations. Nano Lett. 8, 678–684 (2008).

    Article  Google Scholar 

  39. 39

    Yang, S., Prendergast, D. & Neaton, J. B. Tuning semiconductor band edge energies for solar photocatalysis via surface ligand passivation. Nano Lett. 12, 383–388 (2012).

    Article  Google Scholar 

  40. 40

    Munro, A. M., Zacher, B., Graham, A. & Armstrong, N. R. Photoemission spectroscopy of tethered CdSe nanocrystals: shifts in ionization potential and local vacuum level as a function of nanocrystal capping ligand. ACS Appl. Mater. Interfaces 2, 863–869 (2010).

    Article  Google Scholar 

  41. 41

    Jasieniak, J., Califano, M. & Watkins, S. E. Size-dependent valence and conduction band-edge energies of semiconductor nanocrystals. ACS Nano 5, 5888–5902 (2011).

    Article  Google Scholar 

  42. 42

    Geyer, S. M. et al. Control of the carrier type in InAs nanocrystal films by predeposition incorporation of Cd. ACS Nano 4, 7373–7378 (2010).

    Article  Google Scholar 

  43. 43

    Mocatta, D. et al. Heavily doped semiconductor nanocrystal quantum dots. Science 332, 77–81 (2011).

    Article  Google Scholar 

  44. 44

    Sahu, A. et al. Electronic impurity doping in CdSe nanocrystals. Nano Lett. 12, 2587–2594 (2012).

    Article  Google Scholar 

  45. 45

    Choi, J. et al. Bandlike transport in strongly coupled and doped quantum dot solids: a route to high-performance thin-film electronics. Nano Lett. 12, 2631–2638 (2012).

    Article  Google Scholar 

  46. 46

    Gao, J. et al. Quantum dot size dependent J-V characteristics in heterojunction ZnO/PbS quantum dot solar cell. Nano Lett. 11, 1002–1008 (2011).

    Article  Google Scholar 

  47. 47

    Tang, J. et al. Quantum junction solar cells. Nano Lett. 12, 4889–4894 (2012). This paper reports the first quantum junction diodes based on a single materials synthesis and processing platform. It provides a powerful new degree of freedom in CQD optoelectronics.

    Article  Google Scholar 

  48. 48

    Voznyy, O. et al. Charge–orbital balance picture of doping in colloidal quantum dot solids. ACS Nano 6, 8448–8455 (2012).

    Article  Google Scholar 

  49. 49

    Scheele, M. et al. PbS nanoparticles capped with tetrathiafulvalenetetracarboxylate: utilizing energy level alignment for efficient carrier transport. ACS Nano 8, 2532–2540 (2014).

    Article  Google Scholar 

  50. 50

    Koh, W. et al. Heavily doped n-type PbSe and PbS nanocrystals using ground-state charge transfer from cobaltocene. Sci. Rep. 3, 2004 (2013).

    Article  Google Scholar 

  51. 51

    Osedach, T. P. et al. Bias-stress effect in 1,2-ethanedithiol-treated PbS quantum dot field-effect transistors. ACS Nano 6 3121–3127 (2012).

    Article  Google Scholar 

  52. 52

    Engel, J. & Alivisatos, A. P. Postsynthetic doping control of nanocrystal thin films: balancing space charge to improve photovoltaic efficiency. Chem. Mater. 26, 153–162 (2014).

    Article  Google Scholar 

  53. 53

    Ning, Z. et al. Air-stable n-type colloidal quantum dot solids. Nature Mater. 13, 822–828 (2014). This paper reports the first high-performance, air-stable n-type CQD solids. It provides a platform for active electronics that leverage air-stable quantum-tuned materials.

    Article  Google Scholar 

  54. 54

    Luther, J. M. et al. Stoichiometry control in quantum dots: a viable analog to impurity doping of bulk materials. ACS Nano 7, 1845–1849 (2013).

    Article  Google Scholar 

  55. 55

    Zhitomirsky, D. et al. N-type colloidal-quantum-dot solids for photovoltaics. Adv. Mater. 24, 6181–6185 (2012).

    Article  Google Scholar 

  56. 56

    Pattantyus-Abraham, A. G. et al. Depleted-heterojunction colloidal quantum dot solar cells. ACS Nano 4, 3374–3380 (2010).

    Article  Google Scholar 

  57. 57

    Luther, J. M. et al. Efficient, stable infrared photovoltaics based on a 3% PbS/ZnO quantum dot heterojunction solar cell. Adv. Mater. 22, 3704–3707 (2010).

    Article  Google Scholar 

  58. 58

    Tang, J. & Sargent, E. H. Infrared colloidal quantum dots for photovoltaics: fundamentals and recent progress. Adv. Mater. 23, 12–29 (2011).

    Article  Google Scholar 

  59. 59

    Lan, X., Masala, S. & Sargent, E. H. Charge-extraction strategies for colloidal quantum dot photovolatics. Nature Mater. 13, 233–240 (2014).

    Article  Google Scholar 

  60. 60

    Jean, J. et al. ZnO nanowire arrays for enhanced photocurrent in PbS quantum dot solar cells. Adv. Mater. 25, 2790–2796 (2013).

    Article  Google Scholar 

  61. 61

    Wang, H., Kubo, T., Nakazaki, J., Kinoshita, T. & Segawa, H. PbS-quantum-dot-based heterojunctionsolar cells utilizing ZnO nanowires for high external quantum efficiency in the near-infrared region. J. Phys. Chem. Lett. 4, 2455–2460 (2013).

    Article  Google Scholar 

  62. 62

    Labelle, A. et al. Colloidal quantum dot solar cells exploiting hierarchical structuring. Nano Lett. 15, 1101–1108 (2015).

    Article  Google Scholar 

  63. 63

    Adachi, M. M. et al. Broadband solar absorption enhancement via periodic nanostructuring of electrodes. Sci. Rep. 3, 2928 (2013).

    Article  Google Scholar 

  64. 64

    Yuan, M., Voznyy, O., Zhitomirsky, D., Kanjanaboos, P. & Sargent, E. H. Synergistic doping of fullerene electron transport layer and colloidal quantum dot solids enhances solar cell performance. Adv. Mater. 27, 917–921 (2014).

    Article  Google Scholar 

  65. 65

    Choi, J. J. et al. Solution-processed nanocrystal quantum dot tandem solar cells. Adv. Mater. 23, 3144–3148 (2011).

    Article  Google Scholar 

  66. 66

    Liu, H. et al. Systematic optimization of quantum junction colloidal quantum dot solar cells. Appl. Phys. Lett. 101, 151112 (2012).

    Article  Google Scholar 

  67. 67

    Stavrinadis, A. et al. Heterovalent cation substitutional doping for quantum dot homojunction solar cells. Nature Commun. 4, 2981 (2013).

    Article  Google Scholar 

  68. 68

    Rath, A. K. et al. Solution-processed inorganic bulk nano-heterojunctions and their application to solar cells. Nature Photon. 6, 529–534 (2012).

    Article  Google Scholar 

  69. 69

    Rath, A. K., Bernechea, M., Martinez, L. & Konstantatos, G. Solution-processed heterojunction solar cells based on p-type PbS quantum dots and n-type Bi2S3 nanocrystals. Adv. Mater. 23, 3712–3717 (2011).

    Article  Google Scholar 

  70. 70

    Rath, A. K. et al. Remote trap passivation in colloidal quantum dot bulk nano-heterojunctions and its effect in solution-processed solar cells. Adv. Mater. 26, 4741–4747 (2014).

    Article  Google Scholar 

  71. 71

    Ning, Z. et al. Graded doping for enhanced colloidal quantum dot photovoltaics. Adv. Mater. 25, 1719–1723 (2013).

    Article  Google Scholar 

  72. 72

    Yuan, M. et al. Doping control via molecularly-engineered surface ligand coordination, Adv. Mater. 25, 5586–5590 (2013).

    Article  Google Scholar 

  73. 73

    Chuang, C.-H. M., Brown, P. R., Bulovic, V. & Bawendi, M. G. Improved performance and stability in quantum dot solar cells through band alignment engineering. Nature Mater. 13, 796–801 (2014). This paper demonstrates high-performance air-stable quantum dot solar cells through engineering of band alignment at the quantum dot/quantum dot and quantum dot/anode interfaces.

    Article  Google Scholar 

  74. 74

    Nag, A. et al. Metal-free inorganic ligands for colloidal nanocrystals: S2−, HS, Se2−, HSe, Te2−, HTe, TeS32−, OH, and NH2− as surface ligands. J. Am. Chem. Soc. 133, 10612–10620 (2011).

    Article  Google Scholar 

  75. 75

    Nag, A., Zhang, H., Janke, E. & Talapin, D. V. Inorganic surface ligands for colloidal nanomaterials. Z. Phys. Chem. 229, 85–107 (2015).

    Article  Google Scholar 

  76. 76

    Kim, D. K., Lai, Y., Diroll, B. T., Murray, C. B. & Kagan, C. R. Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors. Nature Commun. 3, 1216 (2012).

    Article  Google Scholar 

  77. 77

    Kovalenko, M. V., Scheele, M. & Talapin, D. V. Colloidal nanocrystals with molecular metal chalcogenide surface ligands. Science 324, 1417–1420 (2009). This paper demonstrates all-inorganic ligand-capped nanocrystals for highly efficient field-effect transistors.

    Article  Google Scholar 

  78. 78

    Kovalenko, M. V., Bodnarchuk, M. I., Zaumseil, J., Lee, J. & Talapin, D. V. Expanding the chemical versatility of colloidal nanocrystals capped with molecular metal chalcogenide ligands. J. Am. Chem. Soc. 132, 10085–10092 (2010).

    Article  Google Scholar 

  79. 79

    Lee, J., Kovalenko, M. V., Huang, J., Chung, D. S. & Talapin, D. V. Band-like transport, high electron mobility and high photoconductivity in all-inorganic nanocrystal arrays. Nature Nanotech. 6, 348–352 (2011).

    Article  Google Scholar 

  80. 80

    Ning, Z., Dong, H., Zhang, Q., Voznyy, O. & Sargent, E. H. Solar cells based on inks of n-type colloidal quantum dots. ACS Nano 8, 10321–10327 (2014).

    Article  Google Scholar 

  81. 81

    Yang, Z. et al. Colloidal quantum dot photovoltaics enhanced by perovskite shelling. Nano Lett. 15, 7539–7543 (2015).

    Article  Google Scholar 

  82. 82

    Fischer, A. et al. Directly deposited quantum dot solids using a colloidally stable nanoparticle ink. Adv. Mater. 25, 5742–5749 (2013).

    Article  Google Scholar 

  83. 83

    Kim, J. Y. et al. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films. Nature Commun. 6, 7772 (2015).

    Article  Google Scholar 

  84. 84

    Carney, R. P. et al. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation. Nature Commun. 2, 335 (2011).

    Article  Google Scholar 

  85. 85

    Zhitomirsky, D. et al. Colloidal quantum dot photovoltaics: the effect of polydispersity. Nano Lett. 12, 1007–1012 (2012).

    Article  Google Scholar 

  86. 86

    Jasieniak, J., Califano, M. & Watkins, S. E. Size-dependent valence and conduction band-edge energies of semiconductor nanocrystal. ACS Nano 5, 5888–5902 (2011).

    Article  Google Scholar 

  87. 87

    Xu, F. et al. Efficient exciton funneling in cascaded PbS quantum dots superstructures. ACS Nano 5, 9950–9957 (2011).

    Article  Google Scholar 

  88. 88

    Kramer, I. J., Levina, L., Debnath, R., Zhitomirsky, D. & Sargent, E. H. Solar cells using quantum funnels. Nano Lett. 11, 3701–3706 (2011).

    Article  Google Scholar 

  89. 89

    Konstantatos, G. et al. Hybrid graphene–quantum dot phototransistors with ultrahigh gain. Nature Nanotech. 7, 363–368 (2012).

    Article  Google Scholar 

  90. 90

    Nie, W. et al. High efficiency organic solar cells with spray coated active layers comprised of a low band gap conjugated polymer. Appl. Phys. Lett. 100, 083301 (2012).

    Article  Google Scholar 

  91. 91

    Akhavan, V. A. et al. Spray-deposited CuInSe2 nanocrystal photovoltaics. Energy Environ. Sci. 3, 1600–1606 (2010).

    Article  Google Scholar 

  92. 92

    Genovese, M. P., Lightcap, I. V. & Kamat, P. V. Sun-believable solar paint. A transformative one-step approach for designing nanocrystalline solar cells. ACS Nano 5, 865–872 (2011).

    Google Scholar 

  93. 93

    Kramer, I. J. et al. Efficient spray-coated colloidal quantum dot solar cell. Adv. Mater. 27, 116–121 (2015).

    Article  Google Scholar 

  94. 94

    Kramer, I. J., Moreno-Bautista, G., Minor, J. C., Kopilovic, D. & Sargent, E. H. Colloidal quantum dot solar cells on curved and flexible substrates. Appl. Phys. Lett. 105, 163902 (2014).

    Article  Google Scholar 

  95. 95

    Kramer, I. J. & Sargent, E. H. The architecture of colloidal quantum dot solar cells: materials to devices. Chem. Rev. 114, 863–882 (2014).

    Article  Google Scholar 

  96. 96

    Ip, A. H. et al. Infrared colloidal quantum dot photovoltaics via coupling enhancement and agglomeration suppression. ACS Nano 9, 8833–8842 (2015).

    Article  Google Scholar 

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This publication is based in part on work supported by Award KUS-11-009-21 made by King Abdullah University of Science and Technology; by the Ontario Research Fund Research Excellence Program; and by the Natural Sciences and Engineering Research Council of Canada.

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Correspondence to Edward H. Sargent.

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Yuan, M., Liu, M. & Sargent, E. Colloidal quantum dot solids for solution-processed solar cells. Nat Energy 1, 16016 (2016).

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