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Solid-State Infrared Upconversion in Perylene Diimides Followed by Direct Electron Injection.
Kevin M Felter1, Maria C Fravventura1, Emma Koster1
1Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
ACS Energy Letters
|January 21, 2020
Summary
This study presents a solid-state triplet-triplet annihilation upconversion method for solar cells, enabling near-infrared light absorption and direct electron injection into titanium dioxide (TiO2). This advances solar energy conversion efficiency.
Area of Science:
- Materials Science
- Photochemistry
- Renewable Energy
Background:
- Triplet-triplet annihilation upconversion (TTA-UC) is a promising method for enhancing light absorption in solar cells.
- Efficient energy transfer and charge separation are crucial for effective TTA-UC in solid-state devices.
Purpose of the Study:
- To demonstrate a solid-state TTA-UC approach for solar cell applications.
- To investigate near-infrared light absorption and subsequent electron injection into an inorganic substrate.
Main Methods:
- Utilized time-resolved microwave photoconductivity (TRMC) experiments.
- Fabricated a trilayer device with a triplet sensitizer (fluorinated zinc phthalocyanine), triplet acceptor (methyl substituted perylenediimide), and titanium dioxide (TiO2) substrate.
Main Results:
- Achieved efficient generation of triplet excited states via intersystem crossing upon 700 nm light absorption.
- Observed Dexter energy transfer to the triplet acceptor, followed by triplet annihilation.
- Confirmed electron injection into TiO2 from the upconverted singlet excited state.
Conclusions:
- The demonstrated solid-state TTA-UC system enables efficient conversion of near-infrared light into charge carriers for solar cells.
- This approach facilitates direct electron injection into inorganic substrates like TiO2, paving the way for improved solar energy harvesting.
