scholarly journals Characterization and Electronic Properties of Heptazine Layers: Towards Promising Interfacial Materials for Organic Optoelectronics

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3826
Author(s):  
Issoufou Ibrahim Zamkoye ◽  
Houda El Gbouri ◽  
Remi Antony ◽  
Bernard Ratier ◽  
Johann Bouclé ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Energy Levels ◽  
Thin Layers ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Organic Optoelectronics ◽  
Atomic Force ◽  
Force Mode ◽  
First Time

For the first time, an original compound belonging to the heptazine family has been deposited in the form of thin layers, both by thermal evaporation under vacuum and spin-coating techniques. In both cases, smooth and homogeneous layers have been obtained, and their properties evaluated for eventual applications in the field of organic electronics. The layers have been fully characterized by several concordant techniques, namely UV-visible spectroscopy, steady-state and transient fluorescence in the solid-state, as well as topographic and conductive atomic force microscopy (AFM) used in Kelvin probe force mode (KPFM). Consequently, the afferent energy levels, including Fermi level, have been determined, and show that these new heptazines are promising materials for tailoring the electronic properties of interfaces associated with printed electronic devices. A test experiment showing an improved electron transfer rate from a tris-(8-hydroxyquinoline) aluminum (Alq3) photo-active layer in presence of a heptazine interlayer is finally presented.

Analysis of Dislocations in CdZnTe Epitaxial Film with Kelvin Probe and Conductive Atomic Force Microscopy

2020 ◽  
Vol 49 (6) ◽  
pp. 3907-3912
Author(s):  
Kun Cao ◽  
Wanqi Jie ◽  
Gangqiang Zha ◽  
Jiangpeng Dong ◽  
Ruiqi Hu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Epitaxial Film ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force

Electrochemical and atomic force microscopy investigations of the effect of CdS on the local electrical properties of CH3NH3PbI3:CdS perovskite solar cells

2017 ◽  
Vol 5 (46) ◽  
pp. 12112-12120 ◽  
Author(s):  
Mingxuan Guo ◽  
Fumin Li ◽  
Lanyu Ling ◽  
Chong Chen
Keyword(s):  
Atomic Force Microscopy ◽  
Solar Cells ◽  
Electrochemical Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Bulk Heterojunction ◽  
Perovskite Solar Cells ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force

The effect of the incorporated CdS on the local optoelectronic properties of CH3NH3PbI3:CdS bulk heterojunction (BHJ) perovskite solar cells (PSCs) are studied using Kelvin probe force microscopy (KPFM), conductive atomic force microscopy (c-AFM) and electrochemical impedance spectroscopy (EIS).

scholarly journals Chemosensing on Miniaturized Plasmonic Substrates

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 275
Author(s):  
Pengcheng Wang ◽  
Rodica Elena Ionescu
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Localized Surface Plasmon Resonance ◽  
Thin Layers ◽  
Localized Surface Plasmon ◽  
Force Microscopy ◽  
Atomic Force ◽  
Model Molecule ◽  
First Time ◽  
Scanning Electron

Round, small-sized coverslips were coated for the first time with thin layers of indium tin oxide (ITO, 10–40 nm)/gold (Au, 2–8 nm) and annealed at 550 °C for several hours. The resulting nanostructures on miniaturized substrates were further optimized for the localized surface plasmon resonance (LSPR) chemosensing of a model molecule—1,2-bis-(4-ppyridyl)-ethene (BPE)—with a detection limit of 10−12 M BPE in an aqueous solution. All the fabrication steps of plasmonic-annealed platforms were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM).

Distinguishing negatively-charged and highly conductive dislocations in gallium nitride using scanning Kelvin probe and conductive atomic force microscopy

2002 ◽  
Vol 743 ◽  
Author(s):  
Blake S. Simpkins ◽  
Edward T. Yu ◽  
Patrick Waltereit ◽  
James S. Speck
Keyword(s):  
Atomic Force Microscopy ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Kelvin Probe Microscopy ◽  
Force Microscopy ◽  
Spatially Correlated ◽  
Atomic Force ◽  
Scanning Kelvin Probe ◽  
Dislocation Type ◽  
Distinct Features

ABSTRACTScanning Kelvin probe microscopy (SKPM) and conductive atomic force microscopy (C-AFM) are used to image surfaces of GaN grown by molecular beam epitaxy (MBE). Numerical simulations are used to assist in the interpretation of SKPM images. Detailed analysis of the same area using both techniques allows imaging of surface potential variations arising from the presence of negatively charged dislocations and dislocation-related current leakage paths. Correlations between the charge state of dislocations, conductivity of leakage current paths, and possibly dislocation type can thereby be established. Approximately 25% of the leakage paths appear to be spatially correlated with negatively charged dislocation features. This is approximately the level of correlation expected due to spatial overlap of randomly distributed, distinct features of the size observed, suggesting that the negatively charged dislocations are distinct from those responsible for localized leakage paths found in GaN. The effects of charged dislocation networks on the local potential profile is modeled and discussed.

Electrical investigation of V-defects in GaN using Kelvin probe and conductive atomic force microscopy

2008 ◽  
Vol 93 (2) ◽  
pp. 022107 ◽  
Author(s):  
A. Lochthofen ◽  
W. Mertin ◽  
G. Bacher ◽  
L. Hoeppel ◽  
S. Bader ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Electrical Investigation ◽  
Atomic Force

scholarly journals Analysis and modification of defective surface aggregates on PCDTBT:PCBM solar cell blends using combined Kelvin probe, conductive and bimodal atomic force microscopy

2017 ◽  
Vol 8 ◽  
pp. 579-589 ◽  
Author(s):  
Hanaul Noh ◽  
Alfredo J Diaz ◽  
Santiago D Solares
Keyword(s):  
Atomic Force Microscopy ◽  
Solar Cell ◽  
Polymer Solar Cells ◽  
Cell Structure ◽  
Electrical Potential ◽  
Kelvin Probe ◽  
Conductive Atomic Force Microscopy ◽  
Systematic Analysis ◽  
Force Microscopy ◽  
Atomic Force

Organic photovoltaic systems comprising donor polymers and acceptor fullerene derivatives are attractive for inexpensive energy harvesting. Extensive research on polymer solar cells has provided insight into the factors governing device-level efficiency and stability. However, the detailed investigation of nanoscale structures is still challenging. Here we demonstrate the analysis and modification of unidentified surface aggregates. The aggregates are characterized electrically by Kelvin probe force microscopy and conductive atomic force microscopy (C-AFM), whereby the correlation between local electrical potential and current confirms a defective charge transport. Bimodal AFM modification confirms that the aggregates exist on top of the solar cell structure, and is used to remove them and to reveal the underlying active layer. The systematic analysis of the surface aggregates suggests that the structure consists of PCBM molecules.

scholarly journals Study of the charge transfer process in the polyaniline/graphite heterojunction by conductive atomic force microscopy

2020 ◽  
pp. 94-98
Author(s):  
N. A. Davletkildeev ◽  
Keyword(s):  
Atomic Force Microscopy ◽  
Oxidative Polymerization ◽  
Pyrolytic Graphite ◽  
Thin Layers ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current Voltage ◽  
Current Voltage Characteristics

Thin layers of polyaniline on the surface of highly oriented pyrolytic graphite are obtained by in-situ chemical oxidative polymerization of aniline. The current-voltage characteristics of the tip/polyaniline/graphite contact, which have a form characteristic of tunnel contacts, have been measured by the method of conducting atomic force microscopy. By modeling the current-voltage characteristics using the Simmons model, the width of the potential barrier is determined, which for the investigated heterojunction is 0,5 nm

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