Near-infrared-to-visible photon upconversion holds great promise for a diverse range of applications. Current photosensitizers for triplet-fusion upconversion across this spectral window often contain either precious or toxic elements and have relatively low efficiencies. Although colloidal nanocrystals have emerged as versatile photosensitizers, the only family of nanocrystals discovered for near-infrared upconversion is the highly toxic lead chalcogenides. Here we report zinc-doped CuInSe2 nanocrystals as a low-cost and lead-free alternate, enabling near-infrared-to-yellow upconversion with an external quantum efficiency reaching 16.7%. When directly merged with photoredox catalysis, this system enables efficient near-infrared-driven organic synthesis and polymerization, which in turn solves the issue of reabsorption loss for nanocrystal-sensitized upconversion. Moreover, the broadband light capture of these nanocrystals enables very rapid reactions under indoor sunlight. Extending the reach of ‘solar synthesis’ into the near-infrared may realize the century-long dream of conducting high-added-value chemical transformations using sunlight.
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All data are available in the Article or the Supplementary Information and can be obtained upon request from the corresponding author. These data are also available via Figshare at https://figshare.com/articles/figure/Data_for_CISe_TTA-UC_and_photoredox/21701204. Source data are provided with this paper.
Zhou, B., Shi, B., Jin, D. & Liu, X. Controlling upconversion nanocrystals for emerging applications. Nat. Nanotechnol. 10, 924–936 (2015).
Wen, S. et al. Future and challenges for hybrid upconversion nanosystems. Nat. Photonics 13, 828–838 (2019).
Zhou, J., Liu, Q., Feng, W., Sun, Y. & Li, F. Upconversion luminescent materials: advances and applications. Chem. Rev. 115, 395–465 (2015).
Schulze, T. F. & Schmidt, T. W. Photochemical upconversion: present status and prospects for its application to solar energy conversion. Energy Environ. Sci. 8, 103–125 (2015).
Chen, G., Qiu, H., Prasad, P. N. & Chen, X. Upconversion nanoparticles: design, nanochemistry, and applications in theranostics. Chem. Rev. 114, 5161–5214 (2014).
Ravetz, B. D. et al. Photoredox catalysis using infrared light via triplet fusion upconversion. Nature 565, 343–346 (2019).
Ciamician, G. The photochemistry of the future. Science 36, 385–394 (1912).
Schultz, D. M. & Yoon, T. P. Solar synthesis: prospects in visible light photocatalysis. Science 343, 1239176 (2014).
Singh-Rachford, T. N. & Castellano, F. N. Photon upconversion based on sensitized triplet–triplet annihilation. Coord. Chem. Rev. 254, 2560–2573 (2010).
Bharmoria, P., Bildirir, H. & Moth-Poulsen, K. Triplet–triplet annihilation based near infrared to visible molecular photon upconversion. Chem. Soc. Rev. 49, 6529–6554 (2020).
Han, S. et al. Lanthanide-doped inorganic nanoparticles turn molecular triplet excitons bright. Nature 587, 594–599 (2020).
Yanai, N. & Kimizuka, N. New triplet sensitization routes for photon upconversion: thermally activated delayed fluorescence molecules, inorganic nanocrystals, and singlet-to-triplet absorption. Acc. Chem. Res. 50, 2487–2495 (2017).
Wu, W., Guo, H., Wu, W., Ji, S. & Zhao, J. Organic triplet sensitizer library derived from a single chromophore (BODIPY) with long-lived triplet excited state for triplet–triplet annihilation based upconversion. J. Org. Chem. 76, 7056–7064 (2011).
Singh-Rachford, T. N. & Castellano, F. N. Low power visible-to-UV upconversion. J. Phys. Chem. A 113, 5912–5917 (2009).
Wu, T. C., Congreve, D. N. & Baldo, M. A. Solid state photon upconversion utilizing thermally activated delayed fluorescence molecules as triplet sensitizer. Appl. Phys. Lett. 107, 031103 (2015).
Islangulov, R. R., Kozlov, D. V. & Castellano, F. N. Low power upconversion using MLCT sensitizers. Chem. Commun., 3776–3778 (2005).
Amemori, S., Sasaki, Y., Yanai, N. & Kimizuka, N. Near-infrared-to-visible photon upconversion sensitized by a metal complex with spin-forbidden yet strong S0–T1 absorption. J. Am. Chem. Soc. 138, 8702–8705 (2016).
Huang, L. et al. Highly effective near-infrared activating triplet–triplet annihilation upconversion for photoredox catalysis. J. Am. Chem. Soc. 142, 18460–18470 (2020).
Wu, M. et al. Solid-state infrared-to-visible upconversion sensitized by colloidal nanocrystals. Nat. Photonics 10, 31–34 (2016).
Huang, Z. et al. Hybrid molecule–nanocrystal photon upconversion across the visible and near-infrared. Nano Lett. 15, 5552–5557 (2015).
Mongin, C., Garakyaraghi, S., Razgoniaeva, N., Zamkov, M. & Castellano, F. N. Direct observation of triplet energy transfer from semiconductor nanocrystals. Science 351, 369–372 (2016).
Mase, K., Okumura, K., Yanai, N. & Kimizuka, N. Triplet sensitization by perovskite nanocrystals for photon upconversion. Chem. Commun. 53, 8261–8264 (2017).
Han, Y., He, S. & Wu, K. Molecular triplet sensitization and photon upconversion using colloidal semiconductor nanocrystals. ACS Energy Lett. 6, 3151–3166 (2021).
Nienhaus, L. et al. Triplet-sensitization by lead halide perovskite thin films for near-infrared-to-visible upconversion. ACS Energy Lett. 4, 888–895 (2019).
Izawa, S. & Hiramoto, M. Efficient solid-state photon upconversion enabled by triplet formation at an organic semiconductor interface. Nat. Photonics 15, 895–900 (2021).
Fückel, B. et al. Singlet oxygen mediated photochemical upconversion of NIR light. J. Phys. Chem. Lett. 2, 966–971 (2011).
Mahboub, M., Huang, Z. & Tang, M. L. Efficient infrared-to-visible upconversion with subsolar irradiance. Nano Lett. 16, 7169–7175 (2016).
Gholizadeh, E. M. et al. Photochemical upconversion of near-infrared light from below the silicon bandgap. Nat. Photonics 14, 585–590 (2020).
Talapin, D. V., Lee, J.-S., Kovalenko, M. V. & Shevchenko, E. V. Prospects of colloidal nanocrystals for electronic and optoelectronic applications. Chem. Rev. 110, 389–458 (2009).
Sandroni, M., Wegner, K. D., Aldakov, D. & Reiss, P. Prospects of chalcopyrite-type nanocrystals for energy applications. ACS Energy Lett. 2, 1076–1088 (2017).
Yarema, O. et al. Highly luminescent, size- and shape-tunable copper indium selenide based colloidal nanocrystals. Chem. Mater. 25, 3753–3757 (2013).
Du, J., Singh, R., Fedin, I., Fuhr, A. S. & Klimov, V. I. Spectroscopic insights into high defect tolerance of Zn:CuInSe2 quantum-dot-sensitized solar cells. Nat. Energy 5, 409–417 (2020).
Du, J. et al. Zn–Cu–In–Se quantum dot solar cells with a certified power conversion efficiency of 11.6%. J. Am. Chem. Soc. 138, 4201–4209 (2016).
Wu, K., Li, H. & Klimov, V. I. Tandem luminescent solar concentrators based on engineered quantum dots. Nat. Photonics 12, 105–110 (2018).
Meinardi, F. et al. Highly efficient large-area colourless luminescent solar concentrators using heavy-metal-free colloidal quantum dots. Nat. Nanotechnol. 10, 878–885 (2015).
Fuhr, A., Yun, H. J., Crooker, S. A. & Klimov, V. I. Spectroscopic and magneto-optical signatures of Cu1+ and Cu2+ defects in copper indium sulfide quantum dots. ACS Nano 14, 2212–2223 (2020).
Han, Y. et al. Triplet sensitization by “self-trapped” excitons of nontoxic CuInS2 nanocrystals for efficient photon upconversion. J. Am. Chem. Soc. 141, 13033–13037 (2019).
Berends, A. C. et al. Radiative and nonradiative recombination in CuInS2 nanocrystals and CuInS2-based core/shell nanocrystals. J. Phys. Chem. Lett. 7, 3503–3509 (2016).
Knowles, K. E. et al. Luminescent colloidal semiconductor nanocrystals containing copper: synthesis, photophysics, and applications. Chem. Rev. 116, 10820–10851 (2016).
Huang, Z. et al. PbS/CdS core–shell quantum dots suppress charge transfer and enhance triplet transfer. Angew. Chem. Int. Ed. 56, 16583–16587 (2017).
Thompson, N. J. et al. Energy harvesting of non-emissive triplet excitons in tetracene by emissive PbS nanocrystals. Nat. Mater. 13, 1039–1043 (2014).
Luo, X. et al. Mechanisms of triplet energy transfer across the inorganic nanocrystal/organic molecule interface. Nat. Commun. 11, 28 (2020).
Luo, X. et al. Triplet energy transfer from CsPbBr3 nanocrystals enabled by quantum confinement. J. Am. Chem. Soc. 141, 4186–4190 (2019).
Monguzzi, A., Mezyk, J., Scotognella, F., Tubino, R. & Meinardi, F. Upconversion-induced fluorescence in multicomponent systems: steady-state excitation power threshold. Phys. Rev. B 78, 195112 (2008).
Haefele, A., Blumhoff, J., Khnayzer, R. S. & Castellano, F. N. Getting to the (square) root of the problem: how to make noncoherent pumped upconversion linear. J. Phys. Chem. Lett. 3, 299–303 (2012).
Zhou, Y., Castellano, F. N., Schmidt, T. W. & Hanson, K. On the quantum yield of photon upconversion via triplet–triplet annihilation. ACS Energy Lett. 5, 2322–2326 (2020).
Huang, Z. et al. Enhanced near-infrared-to-visible upconversion by synthetic control of PbS nanocrystal triplet photosensitizers. J. Am. Chem. Soc. 141, 9769–9772 (2019).
Sasaki, Y. et al. Near-infrared optogenetic genome engineering based on photon-upconversion hydrogels. Angew. Chem. Int. Ed. 58, 17827–17833 (2019).
Neumann, M., Füldner, S., König, B. & Zeitler, K. Metal-free, cooperative asymmetric organophotoredox catalysis with visible light. Angew. Chem. Int. Ed. 50, 951–954 (2011).
Mashraqui, S. H. & Kellogg, R. M. 3-Methyl-2,3-dihydrobenzothiazoles as reducing agent. Dye enhanced photoreactions. Tetrahedron Lett. 26, 1453–1456 (1985).
Anger, F. et al. Enhanced stability of rubrene against oxidation by partial and complete fluorination. J. Phys. Chem. C 120, 5515–5522 (2016).
Theriot Jordan, C. et al. Organocatalyzed atom transfer radical polymerization driven by visible light. Science 352, 1082–1086 (2016).
Xiao, P., Zhang, J., Graff, B., Fouassier, J. P. & Lalevée, J. Rubrene-based green-light-sensitive photoinitiating systems of polymerization. Macromol. Chem. Phys. 218, 1700314 (2017).
Jiang, Y., Wang, C., Rogers, C. R., Kodaimati, M. S. & Weiss, E. A. Regio- and diastereoselective intermolecular [2+2] cycloadditions photocatalysed by quantum dots. Nat. Chem. 11, 1034–1040 (2019).
Zhu, X., Lin, Y., Sun, Y., Beard, M. C. & Yan, Y. Lead-halide perovskites for photocatalytic α-alkylation of aldehydes. J. Am. Chem. Soc. 141, 733–738 (2019).
Huang, Y., Zhu, Y. & Egap, E. Semiconductor quantum dots as photocatalysts for controlled light-mediated radical polymerization. ACS Macro Lett. 7, 184–189 (2018).
Huang, C. et al. Quantum dots enable direct alkylation and arylation of allylic C(sp3)–H bonds with hydrogen evolution by solar energy. Chem 7, 1244–1257 (2021).
K.W. acknowledges financial support from the Chinese Academy of Sciences (YSBR-007), the National Natural Science Foundation of China (22173098, 21975253 and 22209180), the Ministry of Science and Technology of China (2018YFA0208703), the Dalian Institute of Chemical Physics (DICP I 202106) and the Fundamental Research Funds for the Central Universities (20720220009).
The authors declare no competing interests.
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Supplementary Texts 1–4, Table 1, Figs. 1–17 and refs. 1–26.
Supplementary Data 1
Raw data for the TTA-UC parameters listed in Table 1.
Source Data Fig. 1
Fig. 1 source data in spreadsheet.
Source Data Fig. 2
Fig. 2 source data in spreadsheet.
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Liang, W., Nie, C., Du, J. et al. Near-infrared photon upconversion and solar synthesis using lead-free nanocrystals. Nat. Photon. (2023). https://doi.org/10.1038/s41566-023-01156-6