Porous film impregnation method for record-efficiency visible-to-UV photon upconversion and subsolar light harvesting

19 January 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Photon upconversion from visible light to ultraviolet (UV) light is useful for various photochemical reactions such as artificial photosynthesis, but its efficiency has been low under practical film conditions. Here, we demonstrate a film with a record-high visible-to-UV upconversion efficiency of 27.6% by simply soaking a porous film with a low-volatile upconversion solution. Furthermore, by combining this film with a microlens array, a significantly low threshold excitation light intensity of less than 0.60 mW cm−2, at least one order of magnitude lower than solar irradiance, is achieved.


Photon upconversion
UV light
porous film
microlens array

Supplementary materials

Electronic Supplementary Information (ESI)
Experimental details, Transmittance of solvents, TTA-UC results of a solution, absorption and fluorescence spectra, SEM images of a porous film, upconverted photoluminescence intensities for one hour, and threshold excitation light intensity.


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