Tuning of the electronic bandgap in colloidal quantum dots (CQDs) by changing their size enables the spectral response of CQD-based photodetectors1,2,3,4,5 and photovoltaic6,7,8,9,10,11,12 devices to be tailored. Multi-junction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun's broad spectrum. Here, we report the first CQD tandem solar cells using the size-effect tuning of a single CQD material, PbS. We use a graded recombination layer to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell, allowing matched electron and hole currents to meet and recombine. Our tandem solar cell has an open-circuit voltage of 1.06 V, equal to the sum of the two constituent single-junction devices, and a solar power conversion efficiency of up to 4.2%.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Konstantatos, G. et al. Ultrasensitive solution-cast quantum dot photodetectors. Nature 442, 180–183 (2006).
Konstantatos, G., Clifford, J., Levina, L. & Sargent, E. H. Sensitive solution-processed visible-wavelength photodetectors. Nature Photon. 1, 531–534 (2007).
Clifford, J. P. et al. Fast, sensitive and spectrally tuneable colloidal-quantum-dot photodetectors. Nature Nanotech. 4, 40–44 (2009).
Rauch, T. et al. Near-infrared imaging with quantum-dot-sensitized organic photodiodes. Nature Photon. 3, 332–336 (2009).
Sukhovatkin, V., Hinds, S., Brzozowski, L. & Sargent, E. H. Colloidal quantum-dot photodetectors exploiting multiexciton generation. Science 324, 1542–1544 (2009).
Sargent, E. H. Infrared photovoltaics made by solution processing. Nature Photon. 3, 325–331 (2009).
Gur, I., Fromer, N. A., Geier, M. L. & Alivisatos, A. P. Air-stable all-inorganic nanocrystal solar cells processed from solution. Science 31, 462–465 (2005).
Kamat, P. V. Quantum dot solar cells semiconductor nanocrystals as light harvesters. J. Phys. Chem. C 112, 18737–18753 (2008).
Luther, J. M. et al. Schottky solar cells based on colloidal nanocrystal films. Nano Lett. 8, 3488–3492 (2008).
Arango, A. C., Oertel, D. C., Xu, Y., Bawendi, M. G. & Bulovic, V. Heterojunction photovoltaics using printed Colloidal Quantum Dots as a photosensitive layer. Nano Lett. 9, 860–863 (2009).
Koleilat, G. I. et al. Efficient, stable infrared photovoltaics based on solution-cast colloidal quantum dots. ACS Nano 2, 833–840 (2008).
Choi, J. J. et al. PbSe nanocrystal excitonic solar cells. Nano Lett. 9, 3749–3755 (2009).
McDonald, S. A. et al. Solution-processed PbS quantum dot infrared photodetectors and photovoltaics. Nature Mater. 4, 138–142 (2005).
Pattantyus-Abraham, A. G. et al. Depleted-heterojunction colloidal quantum dot solar cells. ACS Nano 4, 3374–3380 (2010).
Lamorte, M. F. & Abbott, D. H. Analysis of AlGaAs–GaInAs cascade solar cell under AM0–AM5 spectra. Solid-State Electron. 22, 467–473 (1979).
Lemorte, M. F. & Abbott, D. H. Computer modeling of a two-junction, monolithic cascade solar cell. IEEE Trans. Electron. Dev. 27, 831–840 (1980).
Yamaguchi, M., Takamoto, T., Araki, K. & Ekins-Daukes, N. Multi-junction III–V solar cells: current status and future potential. Solar Energy 79, 78–85 (2005).
King, R. R. et al. 40% efficient metamorphic GaInP/GaInAs/Ge multijunction solar cell. Appl. Phys. Lett. 90, 183516 (2007).
Hiramoto, M., Suezaki, M. & Yokoyama, M. Effect of thin gold interstitial-layer on the photovoltaic properties of tandem organic solar cell. Chem. Lett. 19, 327–330 (1990).
Yakimov, A. & Forrest, S. R. High photovoltage multiple-heterojunction organic solar cells incorporating interfacial metallic nanoclusters. Appl. Phys. Lett. 80, 1667–1669 (2002).
Kim, J. Y. et al. Efficient tandem polymer solar cells fabricated by all-solution processing. Science 317, 222–225 (2007).
Sista, S. et al. Highly efficient tandem polymer photovoltaic cells. Adv. Mater. 22, 380–383 (2010).
Kroger, M. et al. Role of the deep-lying electronic states of MoO3 in the enhancement of hole-injection in organic thin films. Appl. Phys. Lett. 95, 012301 (2009).
Kurishima, K., Nakajima, H., Yamahata, S., Kobayashi, T. & Matsuoka, Y. Effects of a compositionally-graded InxGa1–xAs base in abrupt-emitter InP/InGaAs heterojunction biopolar transistors. Jpn J. Appl. Phys. 34, 1221–1227 (1995).
Chinn, S. R., Zory, P. S. & Reisinger, A. R. A model for GRIN-SCH-SQW diode lasers. IEEE J. Quantum Electron. 24, 2191–2214 (1998).
This publication is based in part on work supported by an award (no. KUS-11-009-21) made by King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellent Program, by the Natural Sciences and Engineering Research Council (NSERC) of Canada, Angstrom Engineering and Innovative Technology. The authors would like to acknowledge the assistance of M. Greiner and A. Fischer for UPS/XPS measurements and discussions. X.W. was partially supported by an Ontario Post Doctoral Fellowship from the Ontario Ministry of Research and Innovation. G.I.K. was partially supported by NSERC. The electron microscopy described in Supplementary Section SI1 was performed at the Canadian Centre for Electron Microscopy, which is supported by NSERC and other government agencies.
The authors declare no competing financial interests.
About this article
Cite this article
Wang, X., Koleilat, G., Tang, J. et al. Tandem colloidal quantum dot solar cells employing a graded recombination layer. Nature Photon 5, 480–484 (2011). https://doi.org/10.1038/nphoton.2011.123
International Journal of Quantum Chemistry (2021)
Journal of Materials Chemistry C (2021)
Science of The Total Environment (2021)
Lifetime elongation of quantum-dot light-emitting diodes by inhibiting the degradation of hole transport layer
RSC Advances (2021)
Effect of reduced graphene oxide on the sunlight-driven photocatalytic activity of rGO/h-MoO3 nanocomposites
Journal of Physics D: Applied Physics (2021)