Search results for "Semiconductor"

Generation of white LED light by frequency downconversion using a perylene-based dye

2012

A high efficiency white light emitting diode (LED) was fabricated by generation of frequency down-conversion from a GaN/InGaN blue LED. In place of conventional inorganic phosphors, a perylene-based dye was used for colour conversion. The resulting hybrid structure is analysed by focusing on the visual performance of the realised LEDs employing the most relevant photometric parameters of a light source. Preparation of the organic polymer is described as well. The thermal stability of the dye was investigated and a simple structure which avoids colour degradation is proposed.

Inside Front Cover: Long-Living Light-Emitting Electrochemical Cells - Control through Supramolecular Interactions (Adv. Mater. 20/2008)

2008

The Synthesis, Condensation, and Luminescence of Stilbenoid Oligomers with Alkoxysilane End Groups

2001

ABSTRACTA synthetic route to highly luminescent organic semiconductors with curable alkoxysilyl groups is described. Monodisperse oligo(phenylenevinylene)s are rigidly connected to di- and triethoxysilanes via Heck reactions or via cross-metathesis. Hydrolysis of the silicic esters yields silanols condensing to linear and cyclic oligo-OPV-siloxanes or to three-dimensional networks, thus allowing the transformation of small molecules to fluorescent materials with well-defined chromophores. Transparent films are obtained by casting of soluble cyclosiloxanes and from OPV-silanetriols, the latter can be cured to insoluble networks.

Photoelectrical properties of thin films of DMABI derivatives

2011

Organic thin films with semiconducting properties have been intensively studied in nowadays due to very promising applications in organic electronics, for example, organic photovoltaic. Among organic semiconductors, group of indandiones with their photoelectrical properties, thermal and chemical stability are good candidates for use in design of novel molecular electronic devices. We have investigated photoconductivity quantum efficiency and its spectral dependence of two dimetilaminobenzylidene-1,3-indandione derivatives. Values of the photoconductivity threshold energy and optical energy gap are obtained. These results are compared with calculated transfer energy gap estimated according t…

Bis(N-naphthyl-N-phenylamino)benzophenones as exciton-modulating materials for white TADF OLEDs with separated charge and exciton recombination zones

2022

Abstract Organic semiconductors were employed as exciton modulators, blue emitters, hole-transporting materials and hosts with resonant-appropriate singlet and triplet energies for efficient and stable white organic light emitting diodes (OLEDs). Two 4,4'-bis(N-naphthyl-N-phenylamino)benzophenones were synthesized using isomeric N-naphthyl-N-phenylamines as the donors and benzophenone as the acceptor moiety. Molecular design of new compounds allowed to obtain required combination of properties, i.e. blue prompt fluorescence in solid state with singlet energies close to those of the selected blue emitter exhibiting thermally activated delayed fluorescence (TADF), low triplet energies of 2.32…

State of the Art in Alq3-Based Spintronic Devices

2015

Since the first observation of a magnetoresistance signal in a vertical organic spin valve in 2004, tris (8-hydroxyquinoline) aluminium (Alq3) molecule has become a standard material for organic spintronics devices. This chapter will briefly present the state of the art on Alq3-based spintronic devices and the different approaches applied through the years to try to optimize these systems. It will be remarked that, despite extensively investigated, many fundamental questions regarding the spin injection and transport mechanisms through the organic layer are still unclear. The chapter will also present some of the most controversial topics in the organic spintronic area and it will highlight…

Connecting Curable Siloxanes to Luminescent Organic Semiconductors - Monomers for Functional Hybrid Materials

2006

ABSTRACTLuminescent stilbenoid chromophores with two alkoxysilane end groups are prepared via hydrosilylation or condensation / reduction of substituted 5-ring OPVs with hydro- and aminopropylsilanes. Chromophore and curable units are connected via flexible spacers. To obtain compounds with a rigid connection between silane and π-system, iodo- or bromo-OPVs were coupled to alkoxysilanes carrying vinyl- or p-vinylphenyl moieties under Heck conditions. This approach allowed a combined connection of the chromophore to the silane moiety with an extension of the π-system. Hydrolysis of the alkoxysilanes yields silanols condensing to curable three-dimensional networks, thus allowing the transform…

Bulk heterojunctions by boramers for plastic photovoltaics

2009

Sputtered cuprous oxide thin films and nitrogen doping by ion implantation

2016

Abstract The structural, optical and electrical properties of sputtered cuprous oxide thin films have been optimized through post-deposition thermal treatments. Moreover we have studied the effects of nitrogen doping introduced by ion implantation followed by the optimized oxidant thermal annealing. Three concentrations have been used, 0.6 N%, 1.2 N%, and 2.5 N%. Along with the preservation of the Cu 2 O phase, a slight optical band gap narrowing and a significant conductivity enhancement has been observed with respect to the undoped samples. These results can be justified by the absence of further oxygen vacancies promoted by dopant introduction and by the substitution of O atoms by N ones…

All-organic device with integrated chemical filter dedicated to the selective measurement of NO2 in air

2010

Abstract An original organic semiconductor gas sensor devoted to the selective monitoring of nitrogen dioxide in air has been successfully developed. This device combines the great sensitivity and the partial selectivity toward oxidizing gases of a molecular organic semiconductor, copper phthalocyanine, with the O3 filtering selectivity of an organic material, indigo. Experimental measurements highlight filtering yield of indigo close to 100% toward O3 and lower than 10% for NO2. Nanometric indigo layers were realized for the first time by thermal evaporation and characterized by FT-IR spectroscopy. Such all-organic device exhibits a high NO2 sensitivity for low concentrations, a resolution…