Strategies for High-Performance Solid-State Photon Upconversion
Photon upconversion, a process that converts multiple low-energy photons into higher energies, has promising applications such as photovoltaics, bio-imaging, and photo-chemistry. Among the techniques capable of achieving photon upconversion, manipulating the excited states of organic molecules is es...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2022
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| Online Access: | https://hdl.handle.net/1721.1/144821 |
| _version_ | 1811095673296125952 |
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| author | Lin, Ting-An |
| author2 | Baldo, Marc A. |
| author_facet | Baldo, Marc A. Lin, Ting-An |
| author_sort | Lin, Ting-An |
| collection | MIT |
| description | Photon upconversion, a process that converts multiple low-energy photons into higher energies, has promising applications such as photovoltaics, bio-imaging, and photo-chemistry. Among the techniques capable of achieving photon upconversion, manipulating the excited states of organic molecules is especially attractive for practical applications thanks to its capability of being operated with low-intensity incoherent light sources. The performance in solid-state, however, is unsatisfactory for applications due to weak optical absorption, internal losses, and the fundamental limit from the upconverting process—triplet-triplet annihilation (TTA)—itself. In this thesis, we investigate strategies to tackle the limitations in solid-state photon upconversion. First, optical absorption is enhanced via embedding an archetypical solid-state infrared-to-visible upconverter into an optical cavity, which results in 74-fold enhancement in absorption and two-orders-of-magnitude reduction in required excitation intensity down to subsolar flux. Charge-exciton hybrid system is also explored as a second approach to enhance absorption. With detailed mechanism further investigated, the optimized device exhibits 0.04- fold lower excitation intensity without external optical structures. Next, we dive into the internal loss pathways within an upconverter. Consisting of an absorbing and an upconverting layer, solid-state upconverters suffer from back transfer and material aggregation. Here, we demonstrate that a bilayer structure with the absorbing layer diluted into a host material can simultaneously mitigate these losses, which results in 7 times higher efficiency and 6 times lower excitation intensity. Finally, we explore the very interior of photon upconversion—the potential to achieve TTA efficiency beyond its fundamental limit by utilizing high-lying non-emissive excited states. The experimental results manifest our concept as a design rule for further developing limit-breaking TTA molecules. With the strategies to develop high-performance solid-state photon upconverters, we look forward to further advancement in modern technologies that benefit from photon upconversion. |
| first_indexed | 2024-09-23T16:23:56Z |
| format | Thesis |
| id | mit-1721.1/144821 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:23:56Z |
| publishDate | 2022 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1448212022-08-30T03:03:59Z Strategies for High-Performance Solid-State Photon Upconversion Lin, Ting-An Baldo, Marc A. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science Photon upconversion, a process that converts multiple low-energy photons into higher energies, has promising applications such as photovoltaics, bio-imaging, and photo-chemistry. Among the techniques capable of achieving photon upconversion, manipulating the excited states of organic molecules is especially attractive for practical applications thanks to its capability of being operated with low-intensity incoherent light sources. The performance in solid-state, however, is unsatisfactory for applications due to weak optical absorption, internal losses, and the fundamental limit from the upconverting process—triplet-triplet annihilation (TTA)—itself. In this thesis, we investigate strategies to tackle the limitations in solid-state photon upconversion. First, optical absorption is enhanced via embedding an archetypical solid-state infrared-to-visible upconverter into an optical cavity, which results in 74-fold enhancement in absorption and two-orders-of-magnitude reduction in required excitation intensity down to subsolar flux. Charge-exciton hybrid system is also explored as a second approach to enhance absorption. With detailed mechanism further investigated, the optimized device exhibits 0.04- fold lower excitation intensity without external optical structures. Next, we dive into the internal loss pathways within an upconverter. Consisting of an absorbing and an upconverting layer, solid-state upconverters suffer from back transfer and material aggregation. Here, we demonstrate that a bilayer structure with the absorbing layer diluted into a host material can simultaneously mitigate these losses, which results in 7 times higher efficiency and 6 times lower excitation intensity. Finally, we explore the very interior of photon upconversion—the potential to achieve TTA efficiency beyond its fundamental limit by utilizing high-lying non-emissive excited states. The experimental results manifest our concept as a design rule for further developing limit-breaking TTA molecules. With the strategies to develop high-performance solid-state photon upconverters, we look forward to further advancement in modern technologies that benefit from photon upconversion. Ph.D. 2022-08-29T16:14:01Z 2022-08-29T16:14:01Z 2022-05 2022-06-21T19:15:40.210Z Thesis https://hdl.handle.net/1721.1/144821 In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Lin, Ting-An Strategies for High-Performance Solid-State Photon Upconversion |
| title | Strategies for High-Performance Solid-State Photon Upconversion |
| title_full | Strategies for High-Performance Solid-State Photon Upconversion |
| title_fullStr | Strategies for High-Performance Solid-State Photon Upconversion |
| title_full_unstemmed | Strategies for High-Performance Solid-State Photon Upconversion |
| title_short | Strategies for High-Performance Solid-State Photon Upconversion |
| title_sort | strategies for high performance solid state photon upconversion |
| url | https://hdl.handle.net/1721.1/144821 |
| work_keys_str_mv | AT lintingan strategiesforhighperformancesolidstatephotonupconversion |