0000000000917733
AUTHOR
Claudio Cali'
showing 22 related works from this author
Warm white LEDs based on Lumogen® Red and Yellow
2013
One of the most widespread solutions for the production of white LEDs is the frequency downconversion of a part of the light, coming from a blue source, by exciting one or more materials (typically Ce:YAG) that emit at longer wavelength [1]. In this work we report ona simple and less expensive method to fabricate warmwhite-light LEDsusingthe photoluminescence of Lumogen®, a perylene-based polymer dyecommercialized by BASF,that has already beenprovedto be a good substitute for conventi onal inorganic colour conversion [2],[3]. Standard InGaN-based blue LEDs (~ 450 nm) were fabricated on a sapphire substrate by metal organic chemical vapour deposition. Both Lumogen® Yellow, and Red dyes wered…
Indium Tin Oxide Photoablation: Spectroscopic Analysis of the Plume
1999
Analisi spettrale, temporale e spaziale della piuma generata nel processo di fotoablazione laser
2004
Fabbricazione di LED bianchi tramite down-conversion di coloranti basati su perilene
2012
A high efficiency cool white LED was obtained by generation of yellow down-conversion from a GaN/InGaN blue LED. Using photoluminescence of a perylene-based polymer dye we achieved a good substitute for conventional inorganic color conversion.
The p-Type Doping of ZnO: Mirage or Reality?
2015
This chapter deals with a critical review on p-type doping of ZnO. In the past 15 years, ZnO has attracted considerable attention due to its unique properties, which make it a promising material for optoelectronic devices applications. However, a reliable p-type ZnO doping remains a major challenge because of self-compensation effects; thus, despite the advantages of these devices, the fabrication of ZnO-based devices is hampered by the lack of a stable p-type doping. A careful and critical analysis of the results reported in literature raises many doubts about the correctness of the doping-type assignments and, in general, the values of the electrical parameters reported. A historical surv…
Electrochemical Fabrication of Inorganic/Organic Field Effect Transistor
2010
After discovery of conducting polymers and the possibility to modify their electrical properties (from insulating to metallic-like behaviour) by doping and a careful choice of the processing conditions, a large amount of research effort has been devoted to the theoretical understanding of their solid state properties as well as to exploit the possible application of conducting polymers in many technological fields including: large area organic electronics, polymer photovoltaic cell and sensors (1-2). Organic thin-film transistors appears very promising for the development of low cost, flexible and disposable plastic electronics. In order to reduce the operating voltage it has been suggested…
Deposition of High Quality Indium Tin Oxide Films by Monitoring InO Emission Lines
2001
Film di ZnO drogati di tipo p per diffusione termica di atomi di fosforo da substrati di InP
2012
We report on p-type doping of ZnO films grown by pulsed-laser deposition on InP substrates. Electrical properties change of the films, from n-type to p-type, has been observed after postgrowth annealing at 600°C for 1h in air.
Stability improvement of PMMA and Lumogen® coatings for hybrid white LEDs
2014
Hybrid white LEDs employing perylene-based dyes for the frequency down-conversion of blue light, generated by a standard inorganic source, suffer from colour rendering variations due to the degradation of the organic molecule under prolonged irradiation. To avoid such inconvenient, proper encapsulation of the dyes in resins or other polymer matrices can prevent their accelerated ageing; nevertheless, embedding polymers can also exhibit significant bleaching caused by chemico-physical agents. Among all, polymethyl methacrilate (PMMA) is one of the most used materials for the fabrication of hybrid LEDs' colour conversion coatings, therefore its stability needs to be investigated.
Electrochemical methods for carrier type identification of ZnO films grown by pulsed laser deposition on InP.
2013
Acquisizione in tempo reale dello spettro emesso dalla plume durante un processo di fotoablazione
2006
White LED light obtained by frequency down-conversion of perylene-based dyes
2012
Electrochemical fabrication of amorphous TiO2/Poly-3,4 Ethylenedioxythiophene (PEDOT) hybrid structures for electronic devices.
2013
Influence of electrodes layout on hydrothermally-grown GaN/ZnO LEDs
2017
Light-emitting diodes (LEDs) based on zinc oxide, with wide direct band gap, have drawn much attention in the last years. ZnO, which is natural n-type, has excellent physical and chemical properties, is inexpensive, abundant and nontoxic. Unfortunately, the preparation of reproducible and high quality p-type ZnO film is comparatively difficult, due to the low solubility of acceptor dopants, self-compensating effects, and acceptor level energy height. Although many groups have reported on ZnO-based homostructure LEDs, the results are controversial as recently reviewed in [1]. Hence, heterojunction LEDs based on ZnO as the nside and GaN as the p-side of the junction have been put forward [2].…
Characterization of charge transport in molecular organic films by the Time of Flight method
2004
Warm white LED light by frequency down- conversion of mixed perylene-based dyes
2013
The growing demand of the solid-state lighting market for the development of sources for illumination has led to the fabrication of the first white LED in 1997, which employed a blue LED coated by a Ce:YAG phosphor to mix the down-converted yellow light with the blue one. The white light appears cold due to the weakness of red components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficacy of warm white LEDs is the mai…
Electrochemical Fabrication of High K Niobium-Tantalum Mixed Oxides/Poly 3-4 Ethylene Dioxythiophene Junctions.
2012
Hybrid LEDs pave way to new lighting applications
2013
Many analysts agree that the global lighting market is close to a real revolution: the LED revolution. One of the most widespread solutions for the production of white LEDs is the conversion of a part of the light, coming from a known source, by exciting one or more materials that emit at a longer wavelength. The result is an emission spectrum given by the superposition of the single source and the photoexcited material; the big advantage is that the phenomenon of photoluminescence replaces the further integration of other solid-state devices of different colors. The photoluminescence of a perylene-based polymer dye turned out to be a good substitute for conventional inorganic color convers…
Growth of device-quality ZnO films by pulsed-laser deposition
2008
In this work, we report on ZnO crystalline growth by pulsed-laser deposition (PLD) on quartz, sapphire, and GaN template. 1 m films were grown under different substrate temperature and background oxygen conditions. X-ray diffraction analysis indicates preferential growth along the c-axis direction with a full-width at half maximum (FWHM) of the rocking curve smaller than 200”. Low-temperature photoluminescence showed A-excitonic emission near 3.36 eV and a FWHM of D0XA emission as small as 2.89 meV at 9 K. The results prove that PLD is a low-cost technique suitable to grow heteroepitaxial ZnO structures for emitting devices.