Formation of Solid-State Excitons in Ultrathin Crystalline Films of PTCDA: From Single Molecules to Molecular Stacks

Proehl, Holger; Dienel, Thomas; Nitsche, Robert; Fritz, Torsten

doi:10.1103/physrevlett.93.097403

Cited by 108 publications

(94 citation statements)

References 20 publications

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“…The interactions among molecular 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9 transition dipoles in such stacks changes the spectral shape noticeably, and the bulk spectrum of PTCDA emerges. 36 It is worthwhile to note that the convergence towards the bulk spectrum takes as much as seven MLEs due to the growth of three-dimensional clusters of disordered PTCDA on ZnO, in contrast to the case on mica where four MLEs are sufficient.…”

Section: Resultsmentioning

confidence: 99%

“…discussion section); this observation indicates that there are no appreciable interactions among the molecular transition dipoles. 32,36 At higher coverages, the formation of PTCDA molecular stacks (or at least piles) is expected. The interactions among molecular 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9 transition dipoles in such stacks changes the spectral shape noticeably, and the bulk spectrum of PTCDA emerges.…”

Section: Resultsmentioning

confidence: 99%

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Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

et al. 2015

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We investigate the prototypical hybrid interface formed between PTCDA and conductive ndoped ZnO films by means of complementary optical and electronic spectroscopic techniques.We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level, but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

et al. 2015

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“…3(a) below). PTCDA thin films are excellent indicators for the sensitivity because their spectral properties highly depend on the detailed arrangement of the molecules on the surface [11]. Our findings are of relevance for a large variety of fields ranging from sensorial applications in industry, environmental studies, and bio-technology to fundamental research concerning thin film growth as well as the controlled interaction of light and matter at the ultimate, microscopic scale.…”

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confidence: 88%

Ultra-sensitive surface absorption spectroscopy using sub-wavelength diameter optical fibers

Warken¹,

Vetsch²,

Meschede³

et al. 2007

Opt. Express

131

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The guided modes of sub-wavelength diameter air-clad optical fibers exhibit a pronounced evanescent field. The absorption of particles on the fiber surface is therefore readily detected via the fiber transmission. We show that the resulting absorption for a given surface coverage can be orders of magnitude higher than for conventional surface spectroscopy. As a demonstration, we present measurements on sub-monolayers of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) molecules at ambient conditions, revealing the agglomeration dynamics on a second to minutes timescale.PACS numbers: 78.66. Qn, 39.30.+w, 68.43.Jk, 78.66.Jg During the last twenty years, numerous optical tools for surface and interface analysis have been developed [1]. The selective sensitivity to surface effects is often obtained by carrying out spectroscopy with evanescent waves (EW), created by total internal reflection of light at the interface. This is straightforwardly realized by exciting waveguide modes in unclad optical fibers [2,3]. If the EW is resonant with the transition frequency of particles (atoms, molecules, quantum dots, etc.) in the surrounding medium, one can use both the particles' fluorescence [4] or the peak attenuation of the waveguide mode [2,5] to infer the concentration of particles at the interface. Moreover, the line shapes allow to spectroscopically retrieve detailed physical information about the nature and strength of the particle-surface interaction.Fiber-based evanescent wave spectroscopy (EWS) is used in various sensors [6]. The robustness, reliability, and ease of use of an all-fiber-based sensor technology is advantageous for in situ sensing in a remote or isolated location or in a harsh environment, e.g., in industrial applications or environmental studies. Furthermore, such sensors also profit from the multiplexing and miniaturization potential inherent to fiber technology. When measuring a volumetric concentration of particles in the surrounding medium, these sensors yield however a reduced sensitivity compared to conventional free-beam absorption: a significant fraction of the light propagates inside the waveguide and therefore does not interact with the particles of interest. This problem can partially be overcome by increasing the power fraction in the EW through proper choice of the fiber mode or geometry [7,8,9]. Yet, even in the ultimate case of 100 % EW, the sensitivity will not exceed that of free-beam absorption techniques.In this letter, we demonstrate that the situation can be dramatically different when employing fiber-based EWS for the spectroscopic study of surface coverages instead of volumetric concentrations: The ultimate sensitivity of fiber-based surface absorption spectroscopy (SAS) is shown to strongly depend on the fiber diameter and to exceed free-beam SAS by several orders of magnitude in the case of sub-wavelength diameter fibers. Fiber-based surface absorption spectroscopy (SAS) has already been used for a number of applications, e.g., in bio-sensors [10]. However, to our kno...

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“…The relation bet− ween the molecular organization of self−assembled mono− layers and their optical properties has been first studied for single−component systems of planar conjugated molecules lying flat on single crystalline surfaces [39,40]. The symme− try breaking towards a non−centrosymmetric arrangement of an assembly of octupolar triphenylene−based molecules has also been evidenced [41] with possible consequences on non−linear optical properties of the system.…”

Section: D Molecular Self Assembly For Dye Immobilizationmentioning

confidence: 99%

Self-assembly: mastering photonic processes at nanoscale

Fiorini

Charra

2010

Opto-Electronics Review

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Supramolecular ordering happens as an important parameter for the control of light emission processes. In this review paper, we discuss several examples of application of self-assembly to the realization of nano-structures designed in view of mastering specific photonic processes. This comprises the formation of highly localized plasmon modes in self-organized 2D assemblies of metal nanoparticles, the immobilization of dyes inside highly homogeneous 2D alveolar self-assembled molecular matrices and molecular 3D building blocks designed to combine in-plane periodicity and off-plane π-conjugated protrusions. Finally, we will discuss 3D self-assembly in solution with the example of fluorescent labelling of DNA.

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Formation of Solid-State Excitons in Ultrathin Crystalline Films of PTCDA: From Single Molecules to Molecular Stacks

Cited by 108 publications

References 20 publications

Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

Ultra-sensitive surface absorption spectroscopy using sub-wavelength diameter optical fibers

Self-assembly: mastering photonic processes at nanoscale

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