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Title: Interference-enhanced infrared-to-visible upconversion in solid-state thin films sensitized by colloidal nanocrystals

Infrared-to-visible photon upconversion has potential applications in photovoltaics, sensing, and bioimaging. In this paper, we demonstrate a solid-state thin-film device that utilizes sensitized triplet-triplet exciton annihilation, converting infrared photons absorbed by colloidal lead sulfide nanocrystals (NCs) into visible photons emitted from a luminescent dopant in rubrene at low incident light intensities. A typical bilayer device consisting of a monolayer of NCs and a doped film of rubrene is limited by low infrared absorption in the thin NC film. Here, we augment the bilayer with an optical spacer layer and a silver-film back reflector, resulting in interference effects that enhance the optical field and thus the absorption in the NC film. The interference-enhanced device shows an order-of-magnitude increase in the upconverted emission at the wavelength of λ = 610 nm when excited at λ = 980 nm. Finally, at incident light intensities above 1.1 W/cm 2, the device attains maximum efficiency, converting (1.6 ± 0.2)% of absorbed infrared photons into higher-energy singlet excitons in rubrene.
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Energy Frontier Research Center for Excitonics
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 21; Journal ID: ISSN 0003-6951
American Institute of Physics (AIP)
Research Org:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; doping; photoluminescence; II-VI semiconductors; photons; excitons; thin film devices; colloidal systems; silver; nanocrystals; monolayers
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1361912