Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

Diao, Ying; Tee, Benjamin C. K.; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Héctor A.; Stoltenberg, Randall M.; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C. B.; Bao, Zhenan

doi:10.1038/nmat3650

Cited by 917 publications

(839 citation statements)

References 26 publications

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“…8 As a result, the growth of high-density arrays of organic single crystals is a desirable semiconductor film topology to achieve arrays of highperformance organic TFTs that can be exploited in large-area flexible circuits such as display backplanes. [9][10][11][12] Among different film deposition techniques, evaporation provides high material purity along with controlled thickness and uniformity over large areas. 3 The vapor phase growth of single organic crystals is traditionally performed by physical vapor transport (PVT) in process conditions close to thermodynamics equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Arrays of Pentacene Single Crystals by Stencil Evaporation

Fesenko

Flauraud

Xie

et al. 2016

Crystal Growth & Design

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In order to realize high-performance organic thin-film transistors (TFT), two parameters of the organic semiconducting layer are desired: single crystallinity for high mobility, and patterning for low off currents. High-quality single crystals can be fabricated using vapor techniques such as physical vapor transport (PVT) but they require high temperatures close to thermodynamic 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 2 equilibrium, for example, 240°C for pentacene. Such high temperatures are not ideal for TFT fabrication on plastic substrates and limit the use of PVT in flexible electronics applications.In this work arrays of pentacene single crystals were directly deposited at low temperature of 40°C by vacuum thermal evaporation through micro-fabricated stencil masks (stencil lithography). By decreasing the stencil aperture size down to 1 µm x 1 µm, we were able to limit the nucleation area until only one grain per aperture is nucleated and grown. We studied systematically scaling effects for large singe crystal growth and discuss details of the growth morphology. We found for instance that the formed pentacene crystals are one monolayer thick and the crystal area is much larger than the aperture size. This can be explained by the diffusion of adsorbed molecules on the surface laterally under the shadow mask, where they are protected from other impinging molecules. The diffusion away from the impinging area under the aperture affects the nucleation density inside this area and was used to calculate the diffusion length to nucleation λ N = 0.66 ± 0.11 µm of pentacene on SiO 2 at 40°C. Our diffusion-driven growth of organic single crystals by stencil lithography is a direct method to grow patterned arrays of single crystalline organic thin-film semiconductor layers.

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Section: Introductionmentioning

confidence: 99%

Arrays of Pentacene Single Crystals by Stencil Evaporation

Fesenko

Flauraud

Xie

et al. 2016

Crystal Growth & Design

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“…If studied thin films form epitaxial layers such as having one crystal axis somewhat aligned with the normal to the substrate, the problem simplifies to finding the relationship between the index ellipse and the in-plane crystal orientation. In case of single crystalline epitaxial films, the index ellipse can be found experimentally using, for example, ellipsometry [19] or polarized absorption spectroscopy [21] while the crystal orientation e using the crystal shape [22] or x-ray diffraction (XRD) measurements [16]. In our work, we find optical properties using light microscopy techniques while the in-plane crystal orientation is obtained from preferential crystal cracking directions.…”

Section: Optical and Structural Properties Of Thin Filmsmentioning

confidence: 84%

“…Polarized light microscopy (PLM) is by far the most popular optical technique for imaging highly-crystalline organic thin films [15,16]. The advantages of PLM are good contrast between different crystal orientations, fast image acquisition, submicrometer lateral resolution and large field of view.…”

Section: Introductionmentioning

confidence: 99%

Determination of crystal orientation in organic thin films using optical microscopy

Fesenko

Rolin

Janneck

et al. 2016

Organic Electronics

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“…Beyond the synthesis of new materials, advanced processing techniques promise improved morphological control [40]: These include nucleation agents to adjust crystallite sizes [41], molecular design motifs to tune the directional alignment of polymer chains [42] and fluidcontrolled solution coating to direct crystal alignment and patterning [43].…”

Section: Challengesmentioning

confidence: 99%

The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors

Poelking

2018

Springer Theses

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The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors The rational design of organic semiconductors for optoelectronic devices relies on a detailed understanding of how their molecular and morphological structure condition the energetics and dynamics of charged and excitonic states. Investigating the role of molecular architecture, conformation, orientation and packing, this work reveals mechanisms that shape the spatially resolved densities of states in organic, small-molecular and polymeric heterostructures and mesophases. The underlying computational framework combines multiscale simulations of the material morphology at atomistic and coarse-grained resolution with a long-range-polarized embedding technique to resolve the electronic structure of the molecular solid. We show that longrange electrostatic interactions tie the energetics of microscopic states to the mesoscopic structure, with a qualitative and quantitative impact on charge-carrier level profiles across organic interfaces. The computational approach provides quantitative access to the charge-density-dependent opencircuit voltage of planar heterojunctions. The derived and experimentally verified relationships between molecular orientation, architecture, level profiles and open-circuit voltage rationalize the acceptor-donor-acceptor pattern for donor materials in high-performing solar cells. Proposing a pathway for barrier-less dissociation of charge transfer states, we highlight how mesoscale fields generate charge splitting and detrapping forces in systems with finite interface roughness. The associated design rules reflect the dominant role played by lowest-energy configurations at the interface. Acknowledgements 121 Die (nicht-)lokale Zustandsdichte elektronischer Anregungen in organischen Halbleitern List of Publications 123Bibliography 125 Chapter 1 Organic Electronics in a NutshellThe discovery of conductive polymers in the 1970s [1,2] -rewarded with the Nobel prize in chemistry in the year 2000 -and subsequent development of the first polymeric electronic devices in the 1980s [3-5] have marked the beginnings of a vast interdisciplinary research field referred to as organic electronics. Drawing from both polymeric and small-molecular semiconductors, organic thin-film transistors, solar cells, light-emitting diodes, photodetectors and sensors name just a few out of many applications that make use of the supreme chemical versatility and mechanical flexibility of the underlying "soft" molecular materials. Furthermore enabling low-temperature solution-based processing, printing and spray coating, organic electronics is set to complement the conventional silicon-based electronics in diverse waysadding functionality and improving sustainability. This introductory chapter will provide a short review of the materials and device physics, as well as of new trends and challenges that emerged in the field over the past decade. MaterialsOrganic semiconductors are molecular materials that exist at the interface between orga...

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Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

Cited by 917 publications

References 26 publications

Arrays of Pentacene Single Crystals by Stencil Evaporation

Arrays of Pentacene Single Crystals by Stencil Evaporation

Determination of crystal orientation in organic thin films using optical microscopy

The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors

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