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Effects of magnetic nanoparticles and external magnetostatic field on the bulk heterojunction polymer solar cells.

Wang K, Yi C, Liu C, Hu X, Chuang S, Gong X - Sci Rep (2015)

Bottom Line: In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials.To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field.Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs.

View Article: PubMed Central - PubMed

Affiliation: College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325, USA.

ABSTRACT
The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.

No MeSH data available.


Related in: MedlinePlus

(A) The molecular structures of PTB7-F20 and PC71BM; (B) the conventional device structure of PSCs without incorporating any Fe3O4 magnetic nanoparticels (MNPs); (C) the conventional device structure of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D)–(F) the fabrication procedures of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D) BHJ active layer incorporated with Fe3O4 MNPs was spin-coated on PEDOT:PSS coated ITO substrate; (E) a ferromagnet was suspend above the surface of BHJ composite incorporated with Fe3O4 MNPs layer. The magnetic intensity is ~30–40 G and the distance between the ferromagnet and BHJ composite layer is ~10 cm; (F) oriented Fe3O4 MNPs inside BHJ active layer by an external magnetostatic field. In pre-devices; (G) Drawing of partial enlargement of Fe3O4 MNP in (C), showing an antiparallel relation between the magnetic dipole (caused by the Fe3O4 crystal inside the particle) and electric dipole (caused by the difference of charge density between the inside Fe3O4 and outside organic coater).
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f2: (A) The molecular structures of PTB7-F20 and PC71BM; (B) the conventional device structure of PSCs without incorporating any Fe3O4 magnetic nanoparticels (MNPs); (C) the conventional device structure of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D)–(F) the fabrication procedures of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D) BHJ active layer incorporated with Fe3O4 MNPs was spin-coated on PEDOT:PSS coated ITO substrate; (E) a ferromagnet was suspend above the surface of BHJ composite incorporated with Fe3O4 MNPs layer. The magnetic intensity is ~30–40 G and the distance between the ferromagnet and BHJ composite layer is ~10 cm; (F) oriented Fe3O4 MNPs inside BHJ active layer by an external magnetostatic field. In pre-devices; (G) Drawing of partial enlargement of Fe3O4 MNP in (C), showing an antiparallel relation between the magnetic dipole (caused by the Fe3O4 crystal inside the particle) and electric dipole (caused by the difference of charge density between the inside Fe3O4 and outside organic coater).

Mentions: In MNPs, a coercive electric field is produced among MNPs due to dipole interactions21. If the BHJ composite is incorporated with MNPs and then followed with an external magnetostatic field alignment, an orientated coercive electric field (E) will be created within BHJ composite (see in Fig. 2G). The E is described as: E = (4πσf/ε)222324, where ε is the dielectric permittivity, σ is the surface charge density and f is the volume fraction of MNPs. For example, an additional E of 177.4 V/μm, which is at least 2 times larger than 50–70 V/μm, can be obtained by BHJ composite incorporated with 5% (by volume) of Fe3O4 MNPs. The details in calculation of E are described in Supplementary Information (SI 1). This additional coercive electric field is expected to enlarge the sweep-out rate of photogenerated carriers and suppress charge carrier recombination (both geminate and non-geminate); consequently resulting in enhanced PCEs in BHJ PSCs. In addition, these MNPs are also expected to influence the formation of thin film morphology of BHJ composite due to the motion of these MNPs under an external magnetostatic field23.


Effects of magnetic nanoparticles and external magnetostatic field on the bulk heterojunction polymer solar cells.

Wang K, Yi C, Liu C, Hu X, Chuang S, Gong X - Sci Rep (2015)

(A) The molecular structures of PTB7-F20 and PC71BM; (B) the conventional device structure of PSCs without incorporating any Fe3O4 magnetic nanoparticels (MNPs); (C) the conventional device structure of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D)–(F) the fabrication procedures of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D) BHJ active layer incorporated with Fe3O4 MNPs was spin-coated on PEDOT:PSS coated ITO substrate; (E) a ferromagnet was suspend above the surface of BHJ composite incorporated with Fe3O4 MNPs layer. The magnetic intensity is ~30–40 G and the distance between the ferromagnet and BHJ composite layer is ~10 cm; (F) oriented Fe3O4 MNPs inside BHJ active layer by an external magnetostatic field. In pre-devices; (G) Drawing of partial enlargement of Fe3O4 MNP in (C), showing an antiparallel relation between the magnetic dipole (caused by the Fe3O4 crystal inside the particle) and electric dipole (caused by the difference of charge density between the inside Fe3O4 and outside organic coater).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4363869&req=5

f2: (A) The molecular structures of PTB7-F20 and PC71BM; (B) the conventional device structure of PSCs without incorporating any Fe3O4 magnetic nanoparticels (MNPs); (C) the conventional device structure of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D)–(F) the fabrication procedures of PSCs incorporated with Fe3O4 MNPs and aligned by an external magnetostatic field; (D) BHJ active layer incorporated with Fe3O4 MNPs was spin-coated on PEDOT:PSS coated ITO substrate; (E) a ferromagnet was suspend above the surface of BHJ composite incorporated with Fe3O4 MNPs layer. The magnetic intensity is ~30–40 G and the distance between the ferromagnet and BHJ composite layer is ~10 cm; (F) oriented Fe3O4 MNPs inside BHJ active layer by an external magnetostatic field. In pre-devices; (G) Drawing of partial enlargement of Fe3O4 MNP in (C), showing an antiparallel relation between the magnetic dipole (caused by the Fe3O4 crystal inside the particle) and electric dipole (caused by the difference of charge density between the inside Fe3O4 and outside organic coater).
Mentions: In MNPs, a coercive electric field is produced among MNPs due to dipole interactions21. If the BHJ composite is incorporated with MNPs and then followed with an external magnetostatic field alignment, an orientated coercive electric field (E) will be created within BHJ composite (see in Fig. 2G). The E is described as: E = (4πσf/ε)222324, where ε is the dielectric permittivity, σ is the surface charge density and f is the volume fraction of MNPs. For example, an additional E of 177.4 V/μm, which is at least 2 times larger than 50–70 V/μm, can be obtained by BHJ composite incorporated with 5% (by volume) of Fe3O4 MNPs. The details in calculation of E are described in Supplementary Information (SI 1). This additional coercive electric field is expected to enlarge the sweep-out rate of photogenerated carriers and suppress charge carrier recombination (both geminate and non-geminate); consequently resulting in enhanced PCEs in BHJ PSCs. In addition, these MNPs are also expected to influence the formation of thin film morphology of BHJ composite due to the motion of these MNPs under an external magnetostatic field23.

Bottom Line: In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials.To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field.Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs.

View Article: PubMed Central - PubMed

Affiliation: College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325, USA.

ABSTRACT
The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated with MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.

No MeSH data available.


Related in: MedlinePlus