- The interplay between free charge carriers, charge transfer (CT) states and singlet excitons (S-1) determines the recombination pathway and the resulting open circuit voltage (V-OC) of organic solar cells.
By combining a well-aggregated low bandgap polymer with different blend ratios of the fullerenes PCBM and ICBA, the energy of the CT state (E-CT) is varied by 130 meV while leaving the S-1 energy of the polymer (ES1\[{E_{{{\rm{S}}_1}}}\]) unaffected.
It is found that the polymer exciton dominates the radiative properties of the blend when ECT\[{E_{{\rm{CT}}}}\] approaches ES1\[{E_{{{\rm{S}}_1}}}\], while the V-OC remains limited by the non-radiative decay of the CT state.
It is concluded that an increasing strength of the exciton in the optical spectra of organic solar cells will generally decrease the non-radiative voltage loss because it lowers the radiative V-OC limit (V-OC,V-rad), but not because it is more emissive.
The analysis further suggests that electronic coupling between the CT state and the S-1 will not improveThe interplay between free charge carriers, charge transfer (CT) states and singlet excitons (S-1) determines the recombination pathway and the resulting open circuit voltage (V-OC) of organic solar cells.
By combining a well-aggregated low bandgap polymer with different blend ratios of the fullerenes PCBM and ICBA, the energy of the CT state (E-CT) is varied by 130 meV while leaving the S-1 energy of the polymer (ES1\[{E_{{{\rm{S}}_1}}}\]) unaffected.
It is found that the polymer exciton dominates the radiative properties of the blend when ECT\[{E_{{\rm{CT}}}}\] approaches ES1\[{E_{{{\rm{S}}_1}}}\], while the V-OC remains limited by the non-radiative decay of the CT state.
It is concluded that an increasing strength of the exciton in the optical spectra of organic solar cells will generally decrease the non-radiative voltage loss because it lowers the radiative V-OC limit (V-OC,V-rad), but not because it is more emissive.
The analysis further suggests that electronic coupling between the CT state and the S-1 will not improve the V-OC, but rather reduce the V-OC,V-rad.
It is anticipated that only at very low CT state absorption combined with a fairly high CT radiative efficiency the solar cell benefit from the radiative properties of the singlet excitons.…
MetadatenAuthor details: | Tobias FritschORCiD, Jona KurpiersORCiDGND, Steffen RolandORCiDGND, Nurlan TokmoldinORCiDGND, Safa ShoaeeORCiDGND, Thomas FerronORCiD, Brian A. CollinsORCiD, Silvia JanietzORCiDGND, Koen VandewalORCiDGND, Dieter NeherORCiDGND |
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DOI: | https://doi.org/10.1002/aenm.202200641 |
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ISSN: | 1614-6832 |
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ISSN: | 1614-6840 |
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Title of parent work (English): | Advanced energy materials |
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Publisher: | Wiley-VCH |
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Place of publishing: | Weinheim |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2022/06/28 |
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Publication year: | 2022 |
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Release date: | 2024/05/24 |
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Tag: | external quantum efficiency; organic photovoltaics; ternary blends; voltage losses |
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Volume: | 12 |
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Issue: | 31 |
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Article number: | 2200641 |
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Number of pages: | 11 |
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Funding institution: | (German Science Foundation DFG) [256605806, 460766640]; US National; Science Foundation [1905790]; DOE Office of Science User Facility; [DE-AC02-05CH11231]; Projekt DEAL |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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Publishing method: | Open Access / Hybrid Open-Access |
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License (German): | CC-BY - Namensnennung 4.0 International |
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