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Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells.

Park K, Oh S, Jung D, Chae H, Kim H, Boo JH - Nanoscale Res Lett (2012)

Bottom Line: A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure.For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + 66-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively.The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Brain Korea 21 Physics Research Division, and Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746, Republic of Korea. djung@skku.ac.kr.

ABSTRACT
We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + 66-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm2 (AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs.

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Changes of work functions in the ECHD/Al structures. These are measured from UPS measurements as a function of ECHD thickness.
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Figure 6: Changes of work functions in the ECHD/Al structures. These are measured from UPS measurements as a function of ECHD thickness.

Mentions: The spectra shown in Figure 5a, b illustrate the relationships between the width of the spectrum, the sample work function Φ, and the photon energy hν. By subtracting the binding energy of the low energy cutoff from the high binding energy edge of the UPS spectra, the work function of the sample is obtained [8]. The change in the work function of ECHD/Al for various ECHD thicknesses is shown in Figure 6. As the ECHD thickness increased from 0 to 0.7 nm, Φ decreased by as much as 0.50 eV. However, further increasing the ECHD thickness above 0.7 nm increased the Φ values of ECHD/Al structures. In this experiment, therefore, the minimum Φ value was found for the ECHD (0.7 nm)/Al structure. In this structure, the Φ value was decreased to 3.62 eV from the Φ of Al, which is 4.12 eV.


Hafnium metallocene compounds used as cathode interfacial layers for enhanced electron transfer in organic solar cells.

Park K, Oh S, Jung D, Chae H, Kim H, Boo JH - Nanoscale Res Lett (2012)

Changes of work functions in the ECHD/Al structures. These are measured from UPS measurements as a function of ECHD thickness.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275463&req=5

Figure 6: Changes of work functions in the ECHD/Al structures. These are measured from UPS measurements as a function of ECHD thickness.
Mentions: The spectra shown in Figure 5a, b illustrate the relationships between the width of the spectrum, the sample work function Φ, and the photon energy hν. By subtracting the binding energy of the low energy cutoff from the high binding energy edge of the UPS spectra, the work function of the sample is obtained [8]. The change in the work function of ECHD/Al for various ECHD thicknesses is shown in Figure 6. As the ECHD thickness increased from 0 to 0.7 nm, Φ decreased by as much as 0.50 eV. However, further increasing the ECHD thickness above 0.7 nm increased the Φ values of ECHD/Al structures. In this experiment, therefore, the minimum Φ value was found for the ECHD (0.7 nm)/Al structure. In this structure, the Φ value was decreased to 3.62 eV from the Φ of Al, which is 4.12 eV.

Bottom Line: A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure.For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + 66-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively.The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Brain Korea 21 Physics Research Division, and Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746, Republic of Korea. djung@skku.ac.kr.

ABSTRACT
We have used hafnium metallocene compounds as cathode interfacial layers for organic solar cells [OSCs]. A metallocene compound consists of a transition metal and two cyclopentadienyl ligands coordinated in a sandwich structure. For the fabrication of the OSCs, poly[3,4-ethylenedioxythiophene]:poly(styrene sulfonate), poly(3-hexylthiophene-2,5-diyl) + 66-phenyl C61 butyric acid methyl ester, bis-(ethylcyclopentadienyl)hafnium(IV) dichloride, and aluminum were deposited as a hole transport layer, an active layer, a cathode interfacial layer, and a cathode, respectively. The hafnium metallocene compound cathode interfacial layer improved the performance of OSCs compared to that of OSCs without the interfacial layer. The current density-voltage characteristics of OSCs with an interfacial layer thickness of 0.7 nm and of those without an interfacial layer showed power conversion efficiency [PCE] values of 2.96% and 2.34%, respectively, under an illumination condition of 100 mW/cm2 (AM 1.5). It is thought that a cathode interfacial layer of an appropriate thickness enhances the electron transfer between the active layer and the cathode, and thus increases the PCE of the OSCs.

No MeSH data available.


Related in: MedlinePlus