Prof. Dr. Frédéric Laquai
Academic Research Focus
- Photophysics of excitonic solar cells
- Exciton dissociation, charge carrier generation, transport and recombination in polymer and small molecule organic and hybrid solar cells
- Steady-state and transient all-optical and electro-optical techniques e.g. transient absorption pump-probe spectroscopy and time-resolved photoluminescence spectroscopy
- Exciton dissociation, charge carrier generation, transport and recombination in polymer and small molecule organic and hybrid solar cells
- Steady-state and transient all-optical and electro-optical techniques e.g. transient absorption pump-probe spectroscopy and time-resolved photoluminescence spectroscopy
Fields of Application
Nanomaterials, Photo-(electro)catalysis, Solar Cells / Photovoltaics
Publications
2.
S Alam, C E Petoukhoff, J P Jurado, H Aldosari, X Jiang, T Váry, H A Nasser, A Dahman, W Althobaiti, S P G Lopez, W Alsufyani, P Müller-Buschbaum, V Nádaždy, H Hoppe, F Laquai
Influence of thermal annealing on microstructure, energetic landscape and device performance of P3HT:PCBM-based organic solar cells Journal Article
In: Journal of Physics: Energy, vol. 6, no. 2, pp. 025013, 2024, ISSN: 2515-7655.
@article{nokey,
title = {Influence of thermal annealing on microstructure, energetic landscape and device performance of P3HT:PCBM-based organic solar cells},
author = {S Alam and C E Petoukhoff and J P Jurado and H Aldosari and X Jiang and T V\'{a}ry and H A Nasser and A Dahman and W Althobaiti and S P G Lopez and W Alsufyani and P M\"{u}ller-Buschbaum and V N\'{a}da\v{z}dy and H Hoppe and F Laquai},
url = {https://dx.doi.org/10.1088/2515-7655/ad2498},
doi = {10.1088/2515-7655/ad2498},
issn = {2515-7655},
year = {2024},
date = {2024-03-14},
journal = {Journal of Physics: Energy},
volume = {6},
number = {2},
pages = {025013},
abstract = {Thermal annealing alters the morphology of organic donor-acceptor bulk-heterojunction thin films used in organic solar cells. Here, we studied the influence of thermal annealing on blends of amorphous regio-random (RRa) and semi-crystalline regio-regular (RR) poly (3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C60-butyric acid methyl ester. Since the P3HT:PCBM blend is one of the most studied in the OPV community, the existing research provides a solid foundation for us to compare and benchmark our innovative characterization techniques that have been previously under-utilized to investigate bulk heterojunction organic thin films. Here, we combine advanced novel microscopies and spectroscopies, including polarized light microscopy, photo-deflection spectroscopy, hyperspectral photoluminescence imaging, and energy resolved-electrochemical impedance spectroscopy, with structural characterization techniques, including grazing-incidence wide-angle x-ray scattering, grazing-incidence x-ray diffraction, and Raman spectroscopy, in order to reveal the impact of thermal annealing on the microstructural crystallinity and morphology of the photoactive layer in organic solar cells. Coupled transfer matrix and drift-diffusion simulations were used to study the impact of the density of states on the solar cells’ device performance parameters, namely the short-circuit current (J SC), open circuit voltage (V OC), fill factor (FF), and power conversion efficiency (PCE).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Thermal annealing alters the morphology of organic donor-acceptor bulk-heterojunction thin films used in organic solar cells. Here, we studied the influence of thermal annealing on blends of amorphous regio-random (RRa) and semi-crystalline regio-regular (RR) poly (3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C60-butyric acid methyl ester. Since the P3HT:PCBM blend is one of the most studied in the OPV community, the existing research provides a solid foundation for us to compare and benchmark our innovative characterization techniques that have been previously under-utilized to investigate bulk heterojunction organic thin films. Here, we combine advanced novel microscopies and spectroscopies, including polarized light microscopy, photo-deflection spectroscopy, hyperspectral photoluminescence imaging, and energy resolved-electrochemical impedance spectroscopy, with structural characterization techniques, including grazing-incidence wide-angle x-ray scattering, grazing-incidence x-ray diffraction, and Raman spectroscopy, in order to reveal the impact of thermal annealing on the microstructural crystallinity and morphology of the photoactive layer in organic solar cells. Coupled transfer matrix and drift-diffusion simulations were used to study the impact of the density of states on the solar cells’ device performance parameters, namely the short-circuit current (J SC), open circuit voltage (V OC), fill factor (FF), and power conversion efficiency (PCE).
1.
S Alam, H Aldosari, C E Petoukhoff, T Váry, W Althobaiti, M Alqurashi, H Tang, J I Khan, V Nádaždy, P Müller-Buschbaum, G C Welch, F Laquai
Thermally-Induced Degradation in PM6:Y6-Based Bulk Heterojunction Organic Solar Cells Journal Article
In: Advanced Functional Materials, vol. n/a, no. n/a, pp. 2308076, 2023, ISSN: 1616-301X.
@article{nokey,
title = {Thermally-Induced Degradation in PM6:Y6-Based Bulk Heterojunction Organic Solar Cells},
author = {S Alam and H Aldosari and C E Petoukhoff and T V\'{a}ry and W Althobaiti and M Alqurashi and H Tang and J I Khan and V N\'{a}da\v{z}dy and P M\"{u}ller-Buschbaum and G C Welch and F Laquai},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202308076},
doi = {https://doi.org/10.1002/adfm.202308076},
issn = {1616-301X},
year = {2023},
date = {2023-10-27},
journal = {Advanced Functional Materials},
volume = {n/a},
number = {n/a},
pages = {2308076},
abstract = {Abstract Thermally induced degradation of organic photovoltaic devices hinders the commercialization of this emerging PV technology. Thus, a precise understanding of the origin of thermal device instability, as well as identifying strategies to circumvent degradation is of utmost importance. Here, it investigates thermally-induced degradation of state-of-the-art PBDB-T-2F (PM6):BTP (Y6) bulk heterojunction solar cells at different temperatures and reveal changes of their optical properties, photophysics, and morphology. The open-circuit voltage and fill factor of thermally degraded devices are limited by dissociation and charge collection efficiency differences, while the short-circuit current density is only slightly affected. Energy-resolved electrochemical impedance spectroscopy measurements reveal that thermally degraded samples exhibit a higher energy barrier for the charge-transfer state to charge-separated state conversion. Furthermore, the field dependence of charge generation, recombination, and extraction are studied by time-delayed collection field and transient photocurrent and photovoltage experiments, indicating significant bimolecular recombination limits device performance. Finally, coupled optical-electrical device simulations are conducted to fit the devices’ current-voltage characteristics, enabling us to find useful correlations between optical and electrical properties of the active layers and device performance parameters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Thermally induced degradation of organic photovoltaic devices hinders the commercialization of this emerging PV technology. Thus, a precise understanding of the origin of thermal device instability, as well as identifying strategies to circumvent degradation is of utmost importance. Here, it investigates thermally-induced degradation of state-of-the-art PBDB-T-2F (PM6):BTP (Y6) bulk heterojunction solar cells at different temperatures and reveal changes of their optical properties, photophysics, and morphology. The open-circuit voltage and fill factor of thermally degraded devices are limited by dissociation and charge collection efficiency differences, while the short-circuit current density is only slightly affected. Energy-resolved electrochemical impedance spectroscopy measurements reveal that thermally degraded samples exhibit a higher energy barrier for the charge-transfer state to charge-separated state conversion. Furthermore, the field dependence of charge generation, recombination, and extraction are studied by time-delayed collection field and transient photocurrent and photovoltage experiments, indicating significant bimolecular recombination limits device performance. Finally, coupled optical-electrical device simulations are conducted to fit the devices’ current-voltage characteristics, enabling us to find useful correlations between optical and electrical properties of the active layers and device performance parameters.