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A New Framework for Understanding Recombination-Limited Charge Extraction in Disordered Semiconductors
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Ardalan Armin,
Oskar Sandberg
The Journal of Physical Chemistry Letters, Volume: 15, Issue: 16, Pages: 4416 - 4421
Swansea University Authors:
Austin Kay, DREW RILEY, Paul Meredith , Ardalan Armin, Oskar Sandberg
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DOI (Published version): 10.1021/acs.jpclett.4c00218
Abstract
Recombination of free charges is a key loss mechanism limiting the performance of organic semiconductor-based photovoltaics such as solar cells and photodetectors. The carrier density-dependence of the rate of recombination and the associated rate coefficients are often estimated using transient cha...
| Published in: | The Journal of Physical Chemistry Letters |
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| ISSN: | 1948-7185 1948-7185 |
| Published: |
American Chemical Society (ACS)
2024
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| Online Access: |
Check full text
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa66033 |
| Abstract: |
Recombination of free charges is a key loss mechanism limiting the performance of organic semiconductor-based photovoltaics such as solar cells and photodetectors. The carrier density-dependence of the rate of recombination and the associated rate coefficients are often estimated using transient charge extraction (CE) experiments. These experiments, however, often neglect the effect of recombination during the transient extraction process. In this work, the validity of the CE experiment for low-mobility devices, such as organic semiconductor-based photovoltaics, is investigated using transient drift-diffusion simulations. We find that recombination leads to incomplete CE, resulting in carrier density-dependent recombination rate constants and overestimated recombination orders; an effect that depends on both the charge carrier mobilities and the resistance–capacitance time constant. To overcome this intrinsic limitation of the CE experiment, we present an analytical model that accounts for charge carrier recombination, validate it using numerical simulations, and employ it to correct the carrier density-dependence observed in experimentally determined bimolecular recombination rate constants. |
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| Keywords: |
Carrier dynamics, Electrical properties, Kinetic parameters, Light, Recombination |
| College: |
Faculty of Science and Engineering |
| Funders: |
Research Council of Finland - 357196; Engineering and Physical Sciences Research Council - EP/T028513/1; Llywodraeth Cymru; European Regional Development Fund; Research England; Swansea University |
| Issue: |
16 |
| Start Page: |
4416 |
| End Page: |
4421 |