The generation and transfer of triplet excitons across semiconductor nanomaterial–molecular interfaces will play an important role in emerging photonic and optoelectronic technologies, and understanding the rules that govern such phenomena is essential. The ability to cooperatively merge the photophysical properties of semiconductor quantum dots with those of well-understood and inexpensive molecular chromophores is therefore paramount. Here we show that 1-pyrenecarboxylic acid-functionalized CdSe quantum dots undergo thermally activated delayed photoluminescence. This phenomenon results from a near quantitative triplet–triplet energy transfer from the nanocrystals to 1-pyrenecarboxylic acid, producing a molecular triplet-state ‘reservoir’ that thermally repopulates the photoluminescent state of CdSe through endothermic reverse triplet–triplet energy transfer. The photoluminescence properties are systematically and predictably tuned through variation of the quantum dot–molecule energy gap, temperature and the triplet-excited-state lifetime of the molecular adsorbate. The concepts developed are likely to be applicable to semiconductor nanocrystals interfaced with molecular chromophores, enabling potential applications of their combined excited states.
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This work was supported by the Air Force Office of Scientific Research (FA9550-13-1-0106) and the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under award no. DE-SC0011979. P.M. and M.Z. were supported by award no. DE-SC0016872, funded by the US Department of Energy, Office of Science.
The authors declare no competing financial interests.
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Mongin, C., Moroz, P., Zamkov, M. et al. Thermally activated delayed photoluminescence from pyrenyl-functionalized CdSe quantum dots. Nature Chem 10, 225–230 (2018). https://doi.org/10.1038/nchem.2906
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