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X-Ray Nanoscopy of a Bulk Heterojunction.

Patil N, Skjønsfjell ET, Van den Brande N, Chavez Panduro EA, Claessens R, Guizar-Sicairos M, Van Mele B, Breiby DW - PLoS ONE (2016)

Bottom Line: X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers.The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates.Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway.

ABSTRACT
Optimizing the morphology of bulk heterojunctions is known to significantly improve the photovoltaic performance of organic solar cells, but available quantitative imaging techniques are few and have severe limitations. We demonstrate X-ray ptychographic coherent diffractive imaging applied to all-organic blends. Specifically, the phase-separated morphology in bulk heterojunction photoactive layers for organic solar cells, prepared from a 50:50 blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) and thermally treated for different annealing times is imaged to high resolution. Moreover, using a fast-scanning calorimetry chip setup, the nano-morphological changes caused by repeated thermal annealing applied to the same sample could be monitored. X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers. The quantitative phase contrast images further allow us to estimate the local volume fraction of PCBM across the photovoltaically active layers. The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates. Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

No MeSH data available.


Related in: MedlinePlus

(a) Reconstructed phase contrast high resolution projection of P3HT/PCBM layer isothermally annealed for 7500 s at 127°C. The black line in the projection image corresponds to the PCBM concentration profile shown in (b). The red curve in (b) shows the fitting analysis applied to the PCBM concentration profile using Eq 5. The fitted parameters of L = 6.0 μm and D = 7 x 10−12 cm2 s-1 provide excellent agreement between the experimental data and the model.
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pone.0158345.g004: (a) Reconstructed phase contrast high resolution projection of P3HT/PCBM layer isothermally annealed for 7500 s at 127°C. The black line in the projection image corresponds to the PCBM concentration profile shown in (b). The red curve in (b) shows the fitting analysis applied to the PCBM concentration profile using Eq 5. The fitted parameters of L = 6.0 μm and D = 7 x 10−12 cm2 s-1 provide excellent agreement between the experimental data and the model.

Mentions: Here L is the distance between neighboring PCBM aggregates, χ0 = 50% is the initial concentration of PCBM in the active layer and χb = 12% is the estimated concentration at the base of the aggregate. The area with the highest concentration of PCBM was assumed to be pure PCBM. An assumption for the diffusion analysis was that the distance between the PCBM aggregates is 6.0 μm (c.f. Fig 4). The diffusion coefficient was fitted to be 7 x 10−12 cm2 s-1 corroborating earlier studies.


X-Ray Nanoscopy of a Bulk Heterojunction.

Patil N, Skjønsfjell ET, Van den Brande N, Chavez Panduro EA, Claessens R, Guizar-Sicairos M, Van Mele B, Breiby DW - PLoS ONE (2016)

(a) Reconstructed phase contrast high resolution projection of P3HT/PCBM layer isothermally annealed for 7500 s at 127°C. The black line in the projection image corresponds to the PCBM concentration profile shown in (b). The red curve in (b) shows the fitting analysis applied to the PCBM concentration profile using Eq 5. The fitted parameters of L = 6.0 μm and D = 7 x 10−12 cm2 s-1 provide excellent agreement between the experimental data and the model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4930208&req=5

pone.0158345.g004: (a) Reconstructed phase contrast high resolution projection of P3HT/PCBM layer isothermally annealed for 7500 s at 127°C. The black line in the projection image corresponds to the PCBM concentration profile shown in (b). The red curve in (b) shows the fitting analysis applied to the PCBM concentration profile using Eq 5. The fitted parameters of L = 6.0 μm and D = 7 x 10−12 cm2 s-1 provide excellent agreement between the experimental data and the model.
Mentions: Here L is the distance between neighboring PCBM aggregates, χ0 = 50% is the initial concentration of PCBM in the active layer and χb = 12% is the estimated concentration at the base of the aggregate. The area with the highest concentration of PCBM was assumed to be pure PCBM. An assumption for the diffusion analysis was that the distance between the PCBM aggregates is 6.0 μm (c.f. Fig 4). The diffusion coefficient was fitted to be 7 x 10−12 cm2 s-1 corroborating earlier studies.

Bottom Line: X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers.The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates.Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway.

ABSTRACT
Optimizing the morphology of bulk heterojunctions is known to significantly improve the photovoltaic performance of organic solar cells, but available quantitative imaging techniques are few and have severe limitations. We demonstrate X-ray ptychographic coherent diffractive imaging applied to all-organic blends. Specifically, the phase-separated morphology in bulk heterojunction photoactive layers for organic solar cells, prepared from a 50:50 blend of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) and thermally treated for different annealing times is imaged to high resolution. Moreover, using a fast-scanning calorimetry chip setup, the nano-morphological changes caused by repeated thermal annealing applied to the same sample could be monitored. X-ray ptychography resolves to better than 100 nm the phase-segregated domains of electron donor and electron acceptor materials over a large field of view within the active layers. The quantitative phase contrast images further allow us to estimate the local volume fraction of PCBM across the photovoltaically active layers. The volume fraction gradient for different regions provides insight on the PCBM diffusion across the depletion zone surrounding PCBM aggregates. Phase contrast X-ray microscopy is under rapid development, and the results presented here are promising for future studies of organic-organic blends, also under in situ conditions, e.g., for monitoring the structural stability during UV-Vis irradiation.

No MeSH data available.


Related in: MedlinePlus