Ellipsometric studies on thin film CuPC: C60 blends for solar cell applications

Datta, Dilip; Tripathi, Vibha; Gogoi, Pranjal Kumar; Banerjee, Suman; Kumar, Satyendra

doi:10.1016/j.tsf.2007.12.043

Cited by 37 publications

(20 citation statements)

References 18 publications

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“…Since there are only a few publications concerned with optical spectra of organic blends, [20][21][22][23] no "standard procedure" for a data analysis of coupling effects has emerged. As a first approach, we perform a decomposition into single-component subbands.…”

Section: A Linear Decomposition Into Single-film Subbandsmentioning

confidence: 99%

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene

et al. 2011

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We present optical absorption spectra of mixed films of pentacene (PEN) and perfluoropentacene (PFP) grown on SiO 2 . We investigated the influence of intermolecular coupling between PEN and PFP on the optical spectra by analyzing samples with five different mixing ratios of PFP:PEN with variable angle spectroscopic ellipsometry and differential reflectance spectroscopy. The data show how the spectral shape is influenced by changes in the volume ratio of the two components. By comparison with the pure film spectra an attempt is made to distinguish transitions due to intermolecular coupling between PEN and PFP from transitions caused by interactions of PEN (PFP) with other molecules of the same type. We observe a new transition at 1.6 eV which is not found in the pure film spectra and which we assign to the coupling of PFP and PEN.

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Section: A Linear Decomposition Into Single-film Subbandsmentioning

confidence: 99%

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene

et al. 2011

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“…[21][22][23][24] Apart from the film structure, also intermolecular coupling can significantly affect the optical properties of the mixed system either due to the differences in the film structure compared with the pure films, which results in changes in the intermolecular interactions between molecules of the same compound, 25 or due to a a) Electronic mail: alexander.gerlach@uni-tuebingen.de possible charge transfer between molecules of the two different compounds. [26][27][28][29][30][31] Pentacene (PEN, C 22 H 14 ) and diindenoperylene (DIP, C 32 H 16 ) are two of the most prominent small-molecule organic semiconductors, 13,[33][34][35][36] which exhibit an anomalous ordering in PEN:DIP blends with a smectic-C-like structure. 11 The perfluorinated derivative of PEN (PFP, C 22 F 14 ) has recently attracted significant interest in pure films as well as in blends with PEN.…”

Section: Introductionmentioning

confidence: 99%

Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth

Broch

Gerlach

Lorch

et al. 2013

The Journal of Chemical Physics

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We discuss the result of the competing effects of favourable intermolecular interactions and steric incompatibilities due to the size mismatch of perfluoropentacene (PFP) and diindenoperylene (DIP) on the structure formation and associated optical properties in mixed films. Using real-time grazing incidence X-ray diffraction we investigate the size of coherently scattering islands l(s) as a function of film thickness and mixing ratio. We find that for PFP:DIP 1:2 blends l(s) is by a factor of ~4 smaller than in pure DIP films, while l(s) of the PFP:DIP 2:1 blends is not significantly reduced compared with pure PFP. Yet, we observe an increase in l(s) with film thickness for all of the samples, independent on the mixing ratio. In parallel with the structural characterization we investigate the evolution of the absorption spectra in the visible spectral range and its dependence on l(s) in situ during film growth using differential reflectance spectroscopy. We observe a surprisingly strong effect of changes in the structural order on the shape of ε(2, xy)(E), evident by a pronounced evolution of characteristic peaks in the thickness range from 1.6 nm to 9.6 nm. The combined results of the real-time experiments allow to identify the thickness dependent crystal grain size as the origin of the observed transient effects in the absorption spectra.

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“…Kramers-Kronig consistency in anisotropic pentacene film, not considering a model dielectric function based on electronic density of states at the band edge, has been found to be crucial for the varied optical constants at the various crystallographic directions [19]. In spite of the Kramers-Kronig consistency and the success of Tauc-Lorentz model in inorganic semiconductors, along with the irregularity in application of the various models to organic semiconductors, only a few report exists with application of Tauc-Lorentz model for the true optical constants of important organic semiconductors [20].…”

Section: Introductionmentioning

confidence: 99%

Determination of optical constants of pentacene thin film by spectroscopic ellipsometry

Datta

Kumar

2010

Solar Energy Materials and Solar Cells

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Ellipsometric studies on thin film CuPC: C60 blends for solar cell applications

Cited by 37 publications

References 18 publications

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene

Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth

Determination of optical constants of pentacene thin film by spectroscopic ellipsometry

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