Issue 12, 2022

Harnessing near-infrared light via S0 to T1 sensitizer excitation in a molecular photon upconversion solar cell

Abstract

Integrating molecular photon upconversion via triplet–triplet annihilation (TTA-UC) directly into a solar cell offers a means of harnessing sub-bandgap, near infrared (NIR) photons and surpassing the Shockley–Queisser limit. However, all integrated TTA-UC solar cells to date only harness visible light. Here, we incorporate an osmium polypyridal complex (Os) as the triplet sensitizer in a metal ion linked multilayer photoanode that is capable of harnessing NIR light via S0 to T1* excitation, triple energy transfer to a phosphonated bis(9,10-diphenylethynyl)anthracene annihilator (A), TTA-UC, and electron injection into TiO2 from the upcoverted state. The TiO2-A-Zn-Os devices have five-fold higher photocurrent (∼3.5 μA cm−2) than the sum of their parts. IPCE data and excitation intensity dependent measurements indicate that the NIR photons are harvested through a TTA-UC mechanism. Transient absorption spectroscopy is used to show that the low photocurrent, as compared to visible light harnessing TTA-UC solar cells, can be atributed to: (1) slow sensitizer to annihilator triplet energy transfer, (2) a low injection yield for the annihilator, and (3) fast back energy transfer from the upconverted state to the sensitizer. Regardless, these results serve as a proof-of-concept that NIR photons can be harnessed via an S0 to T1* sensitizer excited, integrated TTA-UC solar cell and that further improvements can readily be made by remedying the performance limiting processes noted above.

Graphical abstract: Harnessing near-infrared light via S0 to T1 sensitizer excitation in a molecular photon upconversion solar cell

Supplementary files

Article information

Article type
Paper
Submitted
01 Nov. 2021
Accepted
24 Febr. 2022
First published
28 Febr. 2022

J. Mater. Chem. C, 2022,10, 4947-4954

Author version available

Harnessing near-infrared light via S0 to T1 sensitizer excitation in a molecular photon upconversion solar cell

D. Beery, A. Arcidiacono, J. P. Wheeler, J. Chen and K. Hanson, J. Mater. Chem. C, 2022, 10, 4947 DOI: 10.1039/D1TC05270E

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