Lanthanide-doped inorganic nanoparticles turn molecular triplet excitons bright

Sanyang Han; Renren Deng; Qifei Gu; Limeng Ni; Uyen Huynh; Jiangbin Zhang; Zhigao Yi; Baodan Zhao; Hiroyuki Tamura; Anton Pershin; Hui Xu; Zhiyuan Huang; Shahab Ahmad; Mojtaba Abdi-Jalebi; Aditya Sadhanala; Ming Lee Tang; Artem Bakulin; David Beljonne; Xiaogang Liu; Akshay Rao

doi:10.1038/s41586-020-2932-2

Lanthanide-doped inorganic nanoparticles turn molecular triplet excitons bright

Nature. 2020 Nov;587(7835):594-599. doi: 10.1038/s41586-020-2932-2. Epub 2020 Nov 25.

Authors

Sanyang Han^#¹, Renren Deng^#^{2

3}, Qifei Gu¹, Limeng Ni¹, Uyen Huynh¹, Jiangbin Zhang^{1

4

5}, Zhigao Yi⁶, Baodan Zhao^{1

7}, Hiroyuki Tamura⁸, Anton Pershin⁹, Hui Xu¹⁰, Zhiyuan Huang¹¹, Shahab Ahmad¹², Mojtaba Abdi-Jalebi^{1

13}, Aditya Sadhanala¹, Ming Lee Tang¹¹, Artem Bakulin⁴, David Beljonne⁹, Xiaogang Liu^{14

15

16}, Akshay Rao¹⁷

Affiliations

¹ Cavendish Laboratory, University of Cambridge, Cambridge, UK.
² Cavendish Laboratory, University of Cambridge, Cambridge, UK. [email protected].
³ Institute for Composites Science Innovation, School of Materials Science and Engineering, Zhejiang University, Hangzhou, China. [email protected].
⁴ Department of Chemistry, Imperial College London, London, UK.
⁵ College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China.
⁶ Department of Chemistry, National University of Singapore, Singapore, Singapore.
⁷ State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China.
⁸ Department of Chemical System Engineering, The University of Tokyo, Tokyo, Japan.
⁹ Laboratory for Chemistry of Novel Materials, University of Mons, Mons, Belgium.
¹⁰ School of Chemistry and Material Science, Heilongjiang University, Harbin, China.
¹¹ Department of Chemistry, University of California, Riverside, Riverside, CA, USA.
¹² Advanced Energy Materials Group, Department of Physics, Indian Institute of Technology Jodhpur, Jodhpur, India.
¹³ Institute for Materials Discovery, University College London, London, UK.
¹⁴ Department of Chemistry, National University of Singapore, Singapore, Singapore. [email protected].
¹⁵ The N.1 Institute for Health, National University of Singapore, Singapore, Singapore. [email protected].
¹⁶ Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou, China. [email protected].
¹⁷ Cavendish Laboratory, University of Cambridge, Cambridge, UK. [email protected].

^# Contributed equally.

PMID: 33239799
DOI: 10.1038/s41586-020-2932-2

Abstract

The generation, control and transfer of triplet excitons in molecular and hybrid systems is of great interest owing to their long lifetime and diffusion length in both solid-state and solution phase systems, and to their applications in light emission¹, optoelectronics^2,3, photon frequency conversion^4,5 and photocatalysis^6,7. Molecular triplet excitons (bound electron-hole pairs) are 'dark states' because of the forbidden nature of the direct optical transition between the spin-zero ground state and the spin-one triplet levels⁸. Hence, triplet dynamics are conventionally controlled through heavy-metal-based spin-orbit coupling^9-11 or tuning of the singlet-triplet energy splitting^12,13 via molecular design. Both these methods place constraints on the range of properties that can be modified and the molecular structures that can be used. Here we demonstrate that it is possible to control triplet dynamics by coupling organic molecules to lanthanide-doped inorganic insulating nanoparticles. This allows the classically forbidden transitions from the ground-state singlet to excited-state triplets to gain oscillator strength, enabling triplets to be directly generated on molecules via photon absorption. Photogenerated singlet excitons can be converted to triplet excitons on sub-10-picosecond timescales with unity efficiency by intersystem crossing. Triplet exciton states of the molecules can undergo energy transfer to the lanthanide ions with unity efficiency, which allows us to achieve luminescent harvesting of the dark triplet excitons. Furthermore, we demonstrate that the triplet excitons generated in the lanthanide nanoparticle-molecule hybrid systems by near-infrared photoexcitation can undergo efficient upconversion via a lanthanide-triplet excitation fusion process: this process enables endothermic upconversion and allows efficient upconversion from near-infrared to visible frequencies in the solid state. These results provide a new way to control triplet excitons, which is essential for many fields of optoelectronic and biomedical research.

Publication types

Research Support, Non-U.S. Gov't

Grants and funding

ERC_/European Research Council/International