Enhanced Photovoltaic Response in Ionically Self-Assembled Monolayer Thin-Film Devices

2001 ◽  
Vol 708 ◽  
Author(s):  
Daniela Marciu ◽  
Michael B. Miller ◽  
Carrie Kozikowski ◽  
J. R. Heflin ◽  
Sung Cho ◽  
...  
Keyword(s):  
Conducting Polymer ◽  
Electron Acceptor ◽  
Electrolyte Solutions ◽  
Self Assembled Monolayer ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Scale Thickness ◽  
Electron Hole Pair ◽  
Self Assembled ◽  
The Individual

ABSTRACTWe describe detailed studies of ionically self-assembled monolayer (ISAM) photovoltaic (PV) devices incorporating various electron acceptor materials, such as fullerenes and phthalocyanines. Excitons are generated when the conducting polymer is irradiated, and the electron acceptors aid in dissociating the electron/hole pairs before they can radiatively recombine, thus improving the efficiency of the PV process. The ISAM technique allows the deposition of conducting polymer and electron acceptor materials in alternating layers of nanometer-scale thickness. This ensures that every photoexcited electron-hole pair is in proximity to an electron acceptor, thus minimizing electron-hole recombination and increasing the photocurrent. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. Using the ISAM technique, we have demonstrated that it is possible to create ultrathin films (100 nm) of PV material that have enhanced efficiencies.

Preparation and Characterization of Ag/TiO2-xNx Nanoparticles

2007 ◽  
Vol 534-536 ◽  
pp. 105-108
Author(s):  
Zhong Qing Liu ◽  
Zheng Hua Li ◽  
Yan Ping Zhou ◽  
Chang Chun Ge
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Ultraviolet Light ◽  
Hole Pair ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Photochemical Deposition ◽  
Electron Hole Pair

The Ag/TiO2-xNx nanoparticles were synthesized by photochemical deposition with irradiation of visible light in a TiO2-XNX suspension system. The prepared products were characterized by means of XRD, Uv-vis, and FEM. Its photocatalytic activity was investigated by the decomposition of methylene blue (MB) solution under illumination of visible and ultraviolet light, respectively. Compared to TiO2-xNx, the photocatalytic activity of as–prepared Ag/TiO2-xNx is obviously enhanced due to the decreasing recombination of a photoexcited electron-hole pair. The mechanism in which photocatalytic activity is enhanced is discussed in detail.

scholarly journals Finding Electron-Hole Interaction in Quantum Kinetic Framework

2018 ◽  
Vol 55 (3) ◽  
pp. 43-53
Author(s):  
E. Klotins
Keyword(s):  
Pairwise Interaction ◽  
Hole Pair ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Interaction Terms ◽  
Electron Hole Pair ◽  
Mathematical Techniques ◽  
Self Consistency ◽  
Hole Interaction ◽  
Model Hamiltonians

Abstract The article presents a quantum kinetic framework to study interacting quan¬tum systems. Having the constituting model Hamiltonians of two-band semiconductor and the photoexcited electron-hole pair, their quantum kinetic evolution has been revi-sited. Solution to this nonlinear problem of electron-hole interaction is obtained making use of the self-consistency loop between the densities of photoexcited electrons and holes and the pairwise interaction terms in the constituting model Hamiltonians. In the leading order, this approach supports the required isomorphism between the pairwise interaction and the birth and annihilation operators of the photoexcited electrons and holes as a desirable property. The approach implies the Hilbert space and the tensor product mathematical techniques as an appropriate generalization of the noninteracting electron-hole pair toward several-body systems.

Characterization of Polymer Light Emitting Diodes Fabricated by Ionically Self-Assembled Monolayer Technique

1999 ◽  
Vol 598 ◽  
Author(s):  
D. Marciu ◽  
M. B. Miller ◽  
J. R. Heflin ◽  
M. A. Murray ◽  
A. L. Ritter ◽  
...  
Keyword(s):  
Film Thickness ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Low Cost ◽  
Electrolyte Solutions ◽  
Aluminum Electrode ◽  
Large Area ◽  
Self Assembled Monolayer ◽  
Light Emitting ◽  
Self Assembled

ABSTRACTIonically self-assembled monolayer (ISAM) films are a recently developed class of materials that allows detailed structural and thickness control at the sub-nanometer level combined with ease of manufacturing and low cost. The ISAM fabrication method simply involves the dipping of a charged substrate alternately into polycationic and polyanionic aqueous solutions at room temperatures. Importantly, the ISAM technique yields exceptionally homogeneous, large area films with excellent control of total film thickness. We describe detailed studies of ISAM light emitting diodes incorporating poly(para-phenylene vinylene) (PPV) as the light emitting polymer. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. The effects of the pH and ionic strength of the immersion solutions, the total film thickness, and the PPV thermal conversion parameters on the photoluminescence and electroluminescence yields have been systematically studied. The ISAM process also allows the advantage of depositing well-defined thicknesses of separate polymers at the indium tin oxide and the aluminum electrode interfaces.

scholarly journals Direct monitoring of opto-mechanical switching of self-assembled monolayer films containing the azobenzene group

2011 ◽  
Vol 2 ◽  
pp. 834-844 ◽  
Author(s):  
Einat Tirosh ◽  
Enrico Benassi ◽  
Silvio Pipolo ◽  
Marcel Mayor ◽  
Michal Valášek ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Optical Switching ◽  
Mechanical Response ◽  
Experimental Result ◽  
Self Assembled Monolayer ◽  
Monolayer Films ◽  
Azobenzene Group ◽  
Self Assembled ◽  
The Individual ◽  
And Control

The potential for manipulation and control inherent in molecule-based motors holds great scientific and technological promise. Molecules containing the azobenzene group have been heavily studied in this context. While the effects of the cis–trans isomerization of the azo group in such molecules have been examined macroscopically by a number of techniques, modulations of the elastic modulus upon isomerization in self-assembled films were not yet measured directly. Here, we examine the mechanical response upon optical switching of bis[(1,1'-biphenyl)-4-yl]diazene organized in a self-assembled film on Au islands, using atomic force microscopy. Analysis of higher harmonics by means of a torsional harmonic cantilever allowed real-time extraction of mechanical data. Quantitative analysis of elastic modulus maps obtained simultaneously with topographic images show that the modulus of the cis-form is approximately twice that of the trans-isomer. Quantum mechanical and molecular dynamics studies show good agreement with this experimental result, and indicate that the stiffer response in the cis-form comprises contributions both from the individual molecular bonds and from intermolecular interactions in the film. These results demonstrate the power and insights gained from cutting-edge AFM technologies, and advanced computational methods.

Unravelling the role of electron–hole pair spin in exciton dissociation in squaraine-based organic solar cells by magneto-photocurrent measurements

2018 ◽  
Vol 6 (3) ◽  
pp. 482-490 ◽  
Author(s):  
M. Klein ◽  
S. Majumdar ◽  
P. Zassowski ◽  
W. Stampor
Keyword(s):  
Solar Cells ◽  
Magnetic Fields ◽  
Electron Acceptor ◽  
Organic Solar Cells ◽  
Exciton Dissociation ◽  
Electron Hole ◽  
Photocurrent Generation ◽  
Wide Range ◽  
Electron Hole Pair

A study of photocurrent in SQ based solar cells, using a wide range of magnetic fields and temperatures, reveals that depending on the electron acceptor content, the photocurrent generation is limited by dissociation/recombination of e–h pairs or CT states.

Delayed electron–hole pair recombination in iron(iii)-oxo metal–organic frameworks

2014 ◽  
Vol 16 (11) ◽  
pp. 5044-5047 ◽  
Author(s):  
Katrien G. M. Laurier ◽  
Eduard Fron ◽  
Pedro Atienzar ◽  
Koen Kennes ◽  
Hermenegildo Garcia ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Electron Acceptor ◽  
Redox Reactions ◽  
Methyl Viologen ◽  
Transient Absorption ◽  
Metal Organic Frameworks ◽  
Transient Absorption Spectroscopy ◽  
Electron Hole ◽  
Electron Hole Pair ◽  
Metal Organic

The photodynamic properties of a series of Fe(iii)-MOFs have been examined via redox reactions with N,N,N′,N′-tetramethyl-p-phenylenediamine as an electron donor and methyl viologen as an electron acceptor. Furthermore, photogeneration of long-lived species in MIL-88B(Fe) has been proven via transient absorption spectroscopy.

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