Search results for "Optoelectronics"

Plasmonic Focusing Reduces Ensemble Linewidth of Silver-Coated Gold Nanorods

2008

Silver coating gold nanorods reduces the ensemble plasmon line width by changing the relation connecting particle shape and plasmon resonance wavelength. This change, we term "plasmonic focusing", leads to less variation of resonance wavelengths for the same particle size distribution. We also find smaller single particle linewidth comparing resonances at the same wavelength but show that this does not contribute to the ensemble linewidth narrowing.

Optical switching of quantum states inside self-assembled quantum dots

2008

Abstract Photoluminescence and excitation of photoluminescence spectroscopy have been performed for two kinds of single InAs self-assembled quantum dots grown on GaAs. The presence of unintentional impurities (donors and acceptors) offers the possibility to switch from negative to positively charged excitons by selectively exciting impurity related optical transitions.

La collaboration avec la recherche universitaire vue de l’entreprise. Quelques résultats d’enquêtes dans les secteurs des technologies optoélectroniq…

2011

Analysant les caractéristiques de la demande de connaissances externes des entreprises en fonction de leurs régimes d’innovation, l’article s’intéresse plus particulièrement au rôle donné à la recherche universitaire dans les stratégies d’innovation des entreprises. Les résultats tirés d'enquêtes auprès d’entreprises britanniques et françaises, développant des composants optoélectroniques, mettent en évidence l’existence de deux catégories de recherche : la R-D sur financement propre qui est liée aux objectifs à court terme, et la R-D à moyen et long terme qui dépend du financement externe. La participation de la recherche universitaire à la recherche à court terme de l’entreprise prend la …

TCO/Ag/TCO transparent electrodes for solar cells application

2014

Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the natur…

Influence of doped charge transport layers on efficient perovskite solar cells

2018

Planar vacuum deposited p–i–n methyl ammonium lead tri-iodide perovskite solar cells are prepared with different electron and hole transporting layers, either doped or undoped. The effect of these layers on the solar cells performance (efficiency and stability) is studied. The main benefit of using doped layers lies in the formation of barrier free charge extraction contacts to the electrodes. However, this comes at the cost of increased residual absorption (reducing the current density and efficiency of the cells) and a decreased stability. A generic solar cell structure using undoped charge extraction layers is presented, containing a thin layer of a strong electron acceptor in between th…

Modulating the luminance of organic light-emitting diodes via optical stimulation of a photochromic molecular monolayer at transparent oxide electrode

2020

Nanoscale 12(9), 5444-5451 (2020). doi:10.1039/D0NR00724B

Improving Perovskite Solar Cells: Insights From a Validated Device Model

2017

To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of contacts, the electron and hole transport layers, charge generation, drift and diffusion of charge carriers and recombination. The simulation to the experimental data of vacuum-deposited CH3NH3PbI3 solar cells over multiple thicknesses has been fit and the device behavior under different operating conditions has been studied to delineate the influence of the external bias, charge-carrier mobilities, e…

Solid state ionics and optical materials technology for energy efficiency, solar energy conversion, and environment control

1991

The fundamental electronic properties (including optical) of a solid are determined by the character of the interaction between its ionic and electronic subsystems. The state of the ionic subsystem can be changed persistently and reversibly by an external stimulus (current, light). The pertinent ion-controlled phenomena in the solids (solid electrolytes or mixed conductors) causes the ions to be inserted, extracted, transferred, or absorbed or transforms the states of the ions by redox reactions in the bulk or on the surface of the solid or on the interface of a (laminar or planar) solid ionic heterosystem. Several functions can be accomplished: (1) the optical response function of the soli…

Solid-State Lighting: Simple, Fast, Bright, and Stable Light Sources (Adv. Mater. 7/2012)

2012

Dispersion management in two-photon microscopy by using diffractive optical elements.

2013

We demonstrate efficient generation of wide-field fluorescence signals in two-photon microscopy exploiting diffractive optical elements and short pulses by using a dispersion-compensated beam delivery optics module. Computer-generated holograms are codified onto a phase-only spatial light modulator, which allows for arbitrary single-shot patterning of the sample. Spatiotemporal shaping of the pulse is mandatory to overcome spatial chirp and pulse-front tilt effects that spread both in space and time the irradiance patterns, thus limiting not only the spatial resolution but also the signal-to-noise ratio in two-photon microscopy. By using a multipass amplifier delivering 30 fs, 0.8 mJ pulses…