The Structure of a Tetraazapentacene Molecular Monolayer

Abstract

Langmuir molecular monolayers of a unique tetraazapentacene zwitterionic amphiphile were found to form stripe-like domains that responded strongly to an applied magnetic field. These stripe domains were transferred as Langmuir-Blodgett (LB) films to glass substrates, where they were structurally characterized using five complementary imaging techniques, including scanning second-harmonic generation (SHG) microscopy and capacitance force microscopy. The molecular orientations of adjacent single striped domains of a tetraazapentacene monolayer were determined by SHG polarization measurements. Those structures were shown to be consistent across the various imaging techniques.

Comparison of distributed vs. lumped series resistance modeling of thin-film solar cells and modules: Influence on the geometry-dependent efficiency

“…1 Introduction With increasing power conversion efficiencies [1,2] and lifetimes [3][4][5][6], organic solar cells have matured to approaching the stage of being fabricated as large-area modules [7][8][9]. Experimentally realized large-area organic solar modules showed reduced fill factors and power conversion efficiencies due to the increased resistance of the semitransparent electrode upon upscaling [10][11][12][13][14][15]. Accounting for these upscaling effects, several studies were performed involving model analyses of the geometry-dependent solar cell characteristics based on power loss analysis in a simple equivalent circuit including a single lumped series resistance, i.e., the one-diode model [11,[15][16][17][18].…”

“…Experimentally realized large-area organic solar modules showed reduced fill factors and power conversion efficiencies due to the increased resistance of the semitransparent electrode upon upscaling [10][11][12][13][14][15]. Accounting for these upscaling effects, several studies were performed involving model analyses of the geometry-dependent solar cell characteristics based on power loss analysis in a simple equivalent circuit including a single lumped series resistance, i.e., the one-diode model [11,[15][16][17][18]. Other reports dealt with analyses based on advanced equivalent circuits with continuously distributed elements, i.e., a continuous distribution of one-diode models interconnected by discrete resistors representing the electrodes [3,[19][20][21][22][23].…”

Bottom‐Up Synthesis and Top‐Down Organisation of Semiconductor and Metal Clusters on Surfaces

“…However, dewetting is excluded since it either results in structures confined to the borders of the printed pattern [47] or it yields foam-like structures in mobile molecular monolayers. [48] For some molecular systems, quite regular, but much larger, pattern widths (tens of micrometers) are found; [49,50] they depend on the orientation of the molecules on the surface, which should not play a role at the low coverages in the system under consideration. Indeed, the stripes presented here do not have uniform widths, but they extend over the complete micropatterned area.…”

Liquid‐Crystalline Phase Behavior in a Zwitterionic Tetraazapentacene

“…For example, in recent monolayer studies, we have shown that when alkyl substituted molecules were spread onto a Langmuir trough, the tetraazapentacene zwitterion spontaneously formed striped domains that exhibit refractive index contrast when viewed through a Brewster angle microscope. [29] These stripes, which were a minority component of an otherwise featureless monolayer, exhibited a strong translational response to a static magnetic field. [30] Such domains could also be transferred to a solid substrate for further analysis.…”