Efficient hybrid colloidal quantum dot/organic solar cells mediated by near-infrared sensitizing small molecules

Abstract

Solution-processed semiconductors are promising materials to realize optoelectronic devices that combine high performance with inexpensive manufacturing. In particular, the exploitation of colloidal quantum dots (CQDs) capable of harvesting infrared photons, in conjunction with visible-absorbing organic chromophores, has been demonstrated as an interesting route. Unfortunately, CQD/organic hybrid photovoltaics have been limited to power conversion efficiencies (PCEs) below 10% due to chemical mismatch and difficulties in facilitating charge collection. Here we devise a hybrid architecture that overcomes these limitations by introducing small molecules into the CQD/organic stacked structure. The small molecule complements CQD absorption and creates an exciton cascade with the host polymer, thus enabling efficient energy transfer and also promoting exciton dissociation at heterointerfaces. The resulting hybrid solar cells exhibit PCEs of 13.1% and retain over 80% of their initial PCE after 150 h of continuous operation unencapsulated, outperforming present air-processed solution-cast CQD/organic photovoltaics.

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Fig. 1: Hybrid CQD/polymer structure design strategy.
Fig. 2: Photo-induced carrier dynamics in CQD–organics hybrid films.
Fig. 3: Structure and spectral response of hybrid solar cells.
Fig. 4: Photovoltaic performance.

Data availability

The authors declare that the main data supporting the findings of this study are available within the article and its Supplementary Information. Extra data are available from the authors upon request.

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Acknowledgements

This research was supported by Ontario Research Fund–Research Excellence program (ORF7–Ministry of Research and Innovation, Ontario Research Fund–Research Excellence Round 7); and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. This work was supported by National Research Foundation of Korea (NRF) grants (nos. NRF-2015M1A2A2057509 and NRF-2019R1A2C3008035). J.H.S. and S. Jeong were supported by grant no. NRF-2019M3D1A1078296. A.H.P. was supported by an NSERC CGS-D fellowship.

Author information

S.-W.B., F.P.G.A., S.O.K., S.H. and O.V. developed the idea and prepared the manuscript. S. Jun, G.W., A.H.P., H.R.B. and M.S.J. studied and characterized the carrier dynamics. C.K. and B.K. optimized the record device structure. J.K., J.H.S. and S. Jeong synthesized the CQDs dots and characterized the films. O.O. performed the optical calculations. J.-Y. L. and E.H.S. supervised the project. All authors discussed the results and commented on the manuscript.

Correspondence to Jung-Yong Lee or Edward H. Sargent.

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Supplementary Figs. 1–23, Tables 1–3, Notes 1–6 and refs. 1–14.

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Baek, S., Jun, S., Kim, B. et al. Efficient hybrid colloidal quantum dot/organic solar cells mediated by near-infrared sensitizing small molecules. Nat Energy 4, 969–976 (2019). https://doi.org/10.1038/s41560-019-0492-1

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