Improved efficiency of zinc phthalocyanine/C60 based photovoltaic cells via nanoscale interface modification

Hong, Ziruo; Maennig, B.; Lessmann, Rudolf; Pfeiffer, Martin; Leo, Karl; Simon, Paul

doi:10.1063/1.2739364

Cited by 62 publications

(41 citation statements)

References 12 publications

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“…We focus on multi-layered structures as these enable us to vary the interfacial volume while maintaining the superior mobility of neat films. Alternate deposition of ultrathin layers yields a phasesegregated morphology with superior charge transport vis-à-vis co-sublimed blends 22 .…”

Section: Resultsmentioning

confidence: 99%

Hot photocarrier dynamics in organic solar cells

et al. 2015

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Photocurrent in an organic solar cell is generated by a charge transfer reaction between electron donors and acceptors. Charge transfer is expected to proceed from thermalized states, but this picture has been challenged by recent studies that have investigated the role of hot excitons. Here we show a direct link between excess excitation energy and photocarrier mobility. Charge transfer from excited donor molecules generates hot photocarriers with excess energy coming from the offset between the lowest unoccupied molecular orbital of the donor and that of the acceptor. Hot photocarriers manifest themselves through a short-lived spike in terahertz photoconductivity that decays on a picosecond timescale as carriers thermalize. Different dynamics are observed when exciting the acceptor at its absorption edge to a thermalized state. Charge transfer in this case generates thermalized carriers described by terahertz photoconductivity dynamics consisting of an instrument-limited rise to a long-lived signal.

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Section: Resultsmentioning

confidence: 99%

Hot photocarrier dynamics in organic solar cells

et al. 2015

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“…In case of organic light emitting diodes, these advantages have resulted in first commercially available devices admitting the efficient conversion of electrical energy into light. [5][6][7][8][9][10] Among these concepts, photovoltaic elements based on exciton generation, diffusion to the donor-acceptor interfaces, and subsequent dissociation, are the most promising ones. 3,4 Therefore, various innovative device concepts implementing organic thin films are currently under investigation.…”

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confidence: 99%

Exciton diffusion length in the organic semiconductor diindenoperylene

Kurrle

Pflaum

2008

Applied Physics Letters

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Exciton diffusion and energy transfer in organic solar cells based on dicyanovinyl-terthiophene J. Appl. Phys.The photovoltaic behavior of Schottky barrier devices consisting of a single diindenoperylene ͑DIP͒ layer sandwiched between an indium tin oxide and Ag electrode has been investigated. Correlating the spectral dependence of the photocurrent and the absorption coefficient, we estimated the exciton diffusion length in DIP to ϳ100 nm along the cЈ direction. X-ray structural analysis yielded this length to be in agreement with the average crystallite size, thereby, revealing domain boundaries to be the limiting effect on the exciton transport. The corresponding exciton diffusion constant of 5 ϫ 10 −3 cm 2 / s resembles that of highly ordered single crystals of polyaromatic hydrocarbons.

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“…It has been reported that the nano-scale multilayer heterojunction with ultrathin crystalline organic films can greatly improve photocurrent genration. 13,14 As one of the most promising OPV materials, metal phthalocynine including zinc phthalocyanine (ZnPc) is attracting continual interests due to its high absorption coefficient and good chemical and thermal stability. 15 The growth characteristics of evaporated phthalocynine films have been experimentally and theoretically investigated.…”

Section: Introductionmentioning

confidence: 99%

Structural modifications of zinc phthalocyanine thin films for organic photovoltaic applications

Zhou

Taima

Miyadera

et al. 2012

Journal of Applied Physics

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Zinc phthalocyanine (ZnPc) thin films are vacuum-evaporated on bare indium-tin-oxide (ITO) coated glass by varying substrate temperature and growth rate. The samples are characterized by atomic force microscopy, X-ray diffraction and infrared spectroscopy. The temperature does not play a clear role in the crystalline growth of ZnPc possibly due to the significant structural defects on ITO surface, while it strongly influences the surface morphology and molecular alignment. The relationships between growth characteristics and performances of photovoltaics with planar heterojunction are discussed in detail. Increasing temperature or growth rate leads to a rougher surface morphology, which enables more donor/accepter interface area for photocurrent generation. Moreover, at elevated temperature, more molecules adopt standing-up geometry, resulting in a reduction in overall efficiency. The results imply that low-temperature a) Electronic mail: zhou@se.kanazawa-u.ac.jp, b) Electronic mail: taima@se.kanazawa-u.ac.jp 2 process in order to control the molecular alignment is preferred for efficient organic photovoltaics. By simply increasing the growth rate of ZnPc up to 40 Å/s at room temperature,ZnPc/C60 planar heterojunction shows an efficiency of 1.66%, compared to 1.24% for the cell when ZnPc is prepared at 0.10 Å/s.

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Improved efficiency of zinc phthalocyanine/C60 based photovoltaic cells via nanoscale interface modification

Cited by 62 publications

References 12 publications

Hot photocarrier dynamics in organic solar cells

Hot photocarrier dynamics in organic solar cells

Exciton diffusion length in the organic semiconductor diindenoperylene

Structural modifications of zinc phthalocyanine thin films for organic photovoltaic applications

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