Search results for "Optoelectronic device"
showing 10 items of 14 documents
Growth kinetics of colloidal Ge nanocrystals for light harvesters
2016
Colloidal Ge nanocrystals (NCs) are gaining increased interest because of their potential application in low-cost optoelectronic and light harvesting devices. However, reliable control of colloidal NC synthesis is often an issue and a deeper understanding of the key-role parameters governing NC growth is highly required. Here we report an extended investigation on the growth of colloidal Ge NCs synthesized from a one-pot solution based approach. A systematic study of the effects of synthesis time, temperature and precursor concentration is elucidated in detail. X-ray diffraction (XRD) analysis reveals the presence of crystalline Ge NCs with a mean size (from 5 to 35 nm) decreasing with the …
Validity and reliability of Veloflex to measure active cervical range of motion in asymptomatic and symptomatic subjects
2021
Background Neck pain has a high annual incidence and decreases the cervical active range of motion (ROM). Clinicians use various methods to evaluate cervical range of motion (CROM) that some of them have also been proposed to give instant feedback. Accordingly, this study aimed to examine the validity and reliability of Veloflex (VF) to measure the CROM by comparison with the cervical range of motion (CROM) device, and to examine their test-retest reliability. Methods Thirty-eight healthy and 20 symptomatic participants were evaluated. Cervical flexion-extension, side bending, and rotations were tested in two sessions, first by the CROM and VF and in the second only with the VF. To evaluat…
Smart composite films of nanometric thickness based on copper-iodine coordination polymers. Toward sensors.
2018
One-pot reactions between CuI and methyl or methyl 2-amino-isonicotinate give rise to the formation of two coordination polymers (CPs) based on double zig-zag Cu2I2 chains. The presence of a NH2 group in the isonicotinate ligand produces different supramolecular interactions affecting the Cu-Cu distances and symmetry of the Cu2I2 chains. These structural variations significantly modulate their physical properties. Thus, both CPs are semiconductors and also show reversible thermo/mechanoluminescence. X-ray diffraction studies carried out under different temperature and pressure conditions in combination with theoretical calculations have been used to rationalize the multi-stimuli-responsive …
A review of investigation on 4-substituted 1,8-naphthalimide derivatives
2020
DG acknowledges to the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/177. We are grateful to J. V. Grazulevičius for the valuable comments on the manuscript.
Operating Modes of Sandwiched Light-Emitting Electrochemical Cells
2011
Light-emitting electrochemical cells (LECs) are promising lighting devices in which the redistribution of ionic charges allows for double electronic carrier injection from air-stable electrodes. Uncertainties about the mode of operation are limiting the progress of these devices. Using fast (with respect to the current growth time) but resolutive electrical measurement techniques, the electronic transport mechanism in state-of-the-art sandwiched devices can be monitored as a function of the operation time. The results indicate the formation of doped transport layers adjacent to the electrodes that reduces the extent of the central neutral light-emitting layer where electronic transport is l…
Bi3+doping in 1D ((CH3)3SO)PbI3: A model for defect interactions in halide perovskites
2022
The recently described monodimensional hybrid pseudo-perovskite ((CH3)3SO)PbI3 exhibits complete Pb2+/Bi3+ miscibility in the B site. Heterovalent substitution imposes that charge-compensating defects are introduced in the lattice as well. This paper reports the energetics of point defects and the interaction between charge-compensating defects that occur upon Bi3+ doping in ((CH3)3SO)PbI3. Periodic DFT simulations were employed to analyze the formation energy of Pb2+ vacancies, (CH3)3SO+ vacancies, iodide vacancies, or the insertion of interstitial iodide ions. Solid solutions with a large Bi3+ content were modeled considering different charge compensation defects (Pb2+ vacancies, (CH3)3SO…
High-efficiency silicon-compatible photodetectors based on Ge quantum dots
2011
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 Amer…
Colloidal Nanoplatelet/Conducting Polymer Hybrids: Excitonic And Material Properties
2016
WOS:000370678700053 Here we present the first account of conductive polymer/colloidal nanoplatelet hybrids. For this, we developed DEH-PPV-based polymers with two different anchor groups (sulfide and amine) acting as surfactants for CdSe nanoplatelets, which are atomically flat semiconductor nanocrystals. Hybridization of the polymers with the nanoplatelets in the solution phase was observed to cause strong photoluminescence quenching in both materials. Through steady-state photoluminescence and excitation spectrum measurements, photoluminescence quenching was shown to result from dominant exciton dissociation through charge transfer at the polymer/nanoplatelet interfaces that possess a sta…
ITO top-electrodes via industrial-scale PLD for efficient buffer-layer-free semitransparent perovskite solar cells
2022
The deposition of transparent conductive oxides (TCO) usually employs harsh conditions that are frequently harmful to soft/organic underlayers. Herein, successful use of an industrial pulsed laser deposition (PLD) tool to directly deposit indium tin oxide (ITO) films on semitransparent vacuum-deposited perovskite solar cells without damage to the device stack is demonstrated. The morphological, electronic, and optical properties of the PLD deposited ITO films are optimized. A direct relation between the PLD chamber pressure and the solar cell performance is obtained. The semitransparent perovskite solar cells prepared exclusively by vacuum-assisted techniques had fill factors of 78% and exc…
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
2017
Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15- AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV−visnear-infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with o…