Buildup of Triplet-State Population in Operating TQ1:PC71BM Devices Does Not Limit Their Performance
| Autor: | Safakath Karuthedath, Armantas Melianas, Martijn Kemerink, Julien Gorenflot, Zhipeng Kan, Frédéric Laquai |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
education.field_of_study
Range (particle radiation) Materials science Organic solar cell Population Charge (physics) 02 engineering and technology Condensed Matter Physics 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics 0104 chemical sciences Ultrafast laser spectroscopy General Materials Science Charge carrier Physical and Theoretical Chemistry Triplet state 0210 nano-technology education Den kondenserade materiens fysik Recombination |
| Zdroj: | The Journal of Physical Chemistry Letters. 11:2838-2845 |
| ISSN: | 1948-7185 |
| Popis: | Triplet generation in organic solar cells has been considered a major loss channel. Determining the density of the triplet-state population in an operating device is challenging. Here, we employ transient absorption (TA) spectroscopy on the quinoxaline-thiophene copolymer TQ1 blended with PC71BM, quantify the transient charge and tripletstate densities, and parametrize their generation and recombination dynamics. The charge recombination parameters reproduce the experimentally measured current-voltage characteristics in charge carrier drift-diffusion simulations, and they yield the steady-state charge densities. We demonstrate that triplets are formed by both geminate and nongeminate recombination of charge carriers and decay primarily by triplet-triplet annihilation. Using the charge densities in the rate equations describing triplet-state dynamics, we find that triplet-state densities in devices are in the range of charge carrier densities. Despite this substantial triplet-state buildup, TQ1:PC71BM devices exhibit only moderate geminate recombination and significantly reduced nongeminate charge recombination, with reduction factors between 10(-4) and 10(-3) compared to Langevin recombination. Funding Agencies|King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) [OSR2018-CARF/CCF-3079]; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW 2016.0494] |
| Databáze: | OpenAIRE |
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