Publications associées à Abandon des lampes à incandescence

III-N blue-emitting epi-structures with high densities of dislocations: Fundamental mechanisms for efficiency improvement and applications

Since the dawn of humanity, human beings seeked to light their surroundings for their well-being, security and development. The efficiency of ancient lighting devices, e.g. oil lamps or candles, was in the order of 0.03-0.04% and jumped to 0.4-0.6% with th ...

EPFL2024

The mesoglea buffers the physico-chemical microenvironment of photosymbionts in the upside-down jellyfish Cassiopea sp

Anders Meibom, Niclas Heidelberg Lyndby, Michael Kühl

IntroductionThe jellyfish Cassiopea has a conspicuous lifestyle, positioning itself upside-down on sediments in shallow waters thereby exposing its photosynthetic endosymbionts (Symbiodiniaceae) to light. Several studies have shown how the photosymbionts b ...

FRONTIERS MEDIA SA2023

Ion-Dipole Interaction Enabling Highly Efficient CsPbI3 Perovskite Indoor Photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jie Chen, Haizhou Lu, Xiaoyan Wang, Di Zhang, Ziyun Wang, Meng Li, Xingyu Gao

Metal halide perovskites are ideal candidates for indoor photovoltaics (IPVs) because of their easy-to-adjust bandgaps, which can be designed to cover the spectrum of any artificial light source. However, the serious non-radiative carrier recombination und ...

Wiley-V C H Verlag Gmbh2023

Nanoscale Mapping of Light Emission in Nanospade-Based InGaAs Quantum Wells Integrated on Si(100): Implications for Dual Light-Emitting Devices

Anna Fontcuberta i Morral, Didem Dede, Valerio Piazza, Jean-Baptiste Leran, Raphaël François Lemerle, Wonjong Kim, Nicolas Tappy, Nicholas Paul Morgan, Akshay Balgarkashi, Titouan Charvin

III-V semiconductors outperform Si in many optoelectronics applications due to their high carrier mobility, efficient light emission and absorption processes, and the possibility to engineer their band gap through alloying. However, complementing Si techno ...

2022

All-Dielectric Programmable Huygens' Metasurfaces

Hatice Altug, Andreas Tittl, Aleksandrs Leitis

Low-loss nanostructured dielectric metasurfaces have emerged as a breakthrough platform for ultrathin optics and cutting-edge photonic applications, including beam shaping, focusing, and holography. However, the static nature of their constituent materials ...

2020

Elucidating the role of the InGaN UL in the efficiency of InGaN based light-emitting diodes

Camille Haller

Blue III-nitride light-emitting diodes (LEDs) are widely used nowadays in solid-state lighting, as white light can be produced by combining yellow phosphors and blue LEDs. This technology has the advantage to have a higher luminous efficiency than incandes ...

EPFL2019

Tailoring Triple-Anion Perovskite Material for Indoor Light Harvesting with Restrained Halide Segregation and Record High Efficiency Beyond 36%

Hong Zhang, Zhiwen Zhou, Fangzhou Liu

Indoor photovoltaics are promising to enable self-powered electronic devices for the Internet of Things. Here, reported is a triple-anion CH3NH3PbI2-xBrClx perovskite film, of which the bandgap is specially designed for indoor light harvesting to achieve a ...

2019

A high sensitivity, low noise and high spatial resolution multi-band infrared reflectography camera for the study of paintings and works on paper

Marie Eve Pascale Didier

Background: Infrared reflectography (IRR) remains an important method to visualize underdrawing and compositional changes in paintings. Older IRR camera systems are being replaced with near-infrared cameras consisting of room temperature infrared detector ...

Biomed Central Ltd2017

Light wavelength-dependent E. coli survival changes after simulated solar disinfection of secondary effluent

César Pulgarin, Sami Rtimi, Stefanos Giannakis

In this study, the photoreactivation and the modification of dark repair of E. coli in a simulated secondary effluent were investigated after initial irradiation under different conditions. The simulated solar exposure of the secondary wastewater was follo ...

Royal Society of Chemistry2015

Design rules for efficient compact W-BAN antennas

Anja Skrivervik

Antennas are an important element of Wireless Body Area Network equipments, as the quality of the antenna and its coupling to the channel will be a key component of the quality of the overall link. Indeed, the antenna and its interaction with the body of t ...

IEEE2014

Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

Giulia Tagliabue, Dimos Poulikakos

Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence ...

Nature Publishing Group2014

Investigation of indium-rich InGaN alloys and kinetic growth regime of GaN

Nils Asmus Kristian Kaufmann

Nowadays, light emitting diodes (LEDs) and laser diodes (LDs) are part of our daily life. More and more devices incorporate InGaN-based optoelectronic devices. In fact, since the first demonstration of a candela-class InGaN-based LED in the beginning of th ...

EPFL2013

Illuminant estimation and detection using near infrared

Sabine Süsstrunk

Digital camera sensors are sensitive to wavelengths ranging from the ultraviolet (200-400nm) to the near-infrared (700-100nm) bands. This range is, however, reduced because the aim of photographic cameras is to capture and reproduce the visible spectrum (4 ...

2009

Hard X-ray phase-contrast imaging with the Compact Light Source based on inverse Compton X-rays

Christian David

The first imaging results obtained from a small-size synchrotron are reported. The newly developed Compact Light Source produces inverse Compton X-rays at the intersection point of the counter propagating laser and electron beam. The small size of the inte ...

2009

Strong electric field and nonuniformity effects in GaN/AlN quantum dots revealed by high pressure studies

Nicolas Grandjean

The photoluminescence (PL) from GaN quantum dots (QDs) embedded in AlN has been investigated under hydrostatic pressure. The measured pressure coefficient of emitted light energy [dE(E)/dP] shows a negative value, in contrast with the positive pressure coe ...

2006

Microcavity light emitting diodes in the visible red and near infrared wavelength range

It was about 125 years ago that the light bulb was commercialized by Thomas Edison. No doubt a brilliant invention at the time, today its low power conversion efficiency is one of the reasons why lighting in the western world has such high energy consumpti ...

EPFL2005