1,720,970 research outputs found
The research path to commercialization: A perspective on plasmonic nanoparticles in organic and perovskite optoelectronics
No full textThe emergence of plasmonic nanoparticles in organic and perovskite optoelectronics has evolved beyond its role as a mere light emission and absorption enhancer, by delving into the exotic properties of semiconductor thin films. These properties include stimulated emission (lasing), coherent emission (superradiance), reversible spontaneous emission, and spontaneous synchronization leading to coherent emission. Despite the wealth of available fundamental knowledge, the commercialization of plasmonic nanoparticles in organic and perovskite optoelectronics such as light emitting diodes, photovoltaics and photodetectors, has yet to reach fruition. This paper reviews the technical challenges acting as barriers to commercialization and highlights how their solutions are influenced by economic, sustainability, and regulatory hurdles. A focused examination of technological challenges, including deposition, material compatibility, scalability, and reproducibility of the device performance, is presented. This perspective article concludes by proposing potential solutions and offering a future outlook for the field, emphasizing sustain-ability, the circular economy, and responsible electronics, alongside the continued advancement of fundamental knowledge.The authors would like to thank the UHasselt BOF funding grant number BOF21KP04 for supporting the work
Ultrasonic spray coating of polyethylenimine (ethoxylated) as electron injection and transport layer for organic light emitting diodes: The influence of layer morphology and thickness on the interface physics between polyethylenimine (ethoxylated) and the Al cathode
No full textModern lighting is expected to be light weight, flexible, efficient, non-expensive and environmentally friendly fabricated. Organic light emitting diodes (OLEDs) meet all these requirements and can be manufactured using inexpensive and roll-to-roll compatible printing techniques. They, however, often use low work function, highly reactive metals, such as barium and calcium to facilitate electron injection, deposited using expensive and non-continuous vacuum techniques. Efficient and stable alternatives can be found in the aliphatic amines, polyethylenimine (PEI) and polyethylenimine(ethoxylated) (PEIE), that shift the work function of aluminum favorably for electron injection. This work demonstrates ultrasonic spray coating of PEI(E) as electron injection and transport layer for OLEDs, reducing the work function of the aluminum cathode by 0.355 eV allowing a luminous efficacy comparable to that of the OLEDs using calcium/aluminum electrodes. Slightly higher luminous results are noted for the OLEDs with spin coated PEI(E), indicating that the surface morphology and thickness of the PEI(E) layer are crucial factors: ultrasonic spray coated PEI(E) layers have an increased overall thickness and surface roughness. This study shows the potential of ultrasonic spray coating and the suitability of PEI(E) as excellent electron injection and transport layer for OLEDs and paves the way towards fully spray coated OLEDs. K E Y W O R D S electron injection and transport layer, organic light emitting diodes, printing techniques, ultrasonic spray coating This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.BOF UHasselt, Grant/Award Number: BOF20DCOV09; FWO-Vlaanderen, Grant/Award Number: G043320
Correlated nanoimaging of structure and dynamics of cation-polaron coupling in hybrid perovskites
No full textHybrid organic-inorganic perovskites exhibit high photovoltaic performance and other novel photonic functions. While polaron formation is believed to facilitate efficient carrier transport, the elementary processes of the underlying electron-lattice coupling are yet poorly understood because of the multiscale chemical and structural heterogeneities. Here, we resolve in combined ground- and excited-state spatiospectral ultrafast nanoimaging how structural characteristics are related to both molecular cation and polaron dynamics. We use the observed nanoscale spatial variations of the formamidinium (FA) cation transient vibrational blue shifts as a local probe of the nonlocal polaron-cation coupling. From the correlation with nanomovies of the polaron dynamics, we then infer how a softer more polarizable lattice supports stable polarons and longer-lived residual carriers. This, together with a relative intragrain homogeneity in contrast to high intergrain heterogeneity, suggests pathways for improved synthesis and device engineering, and that perovskite photonics performance is still far from any fundamental limits.Acknowledgments:
We thank J. Nishida for many helpful discussions about pump-probe nanoimaging. We thank A. Neukirch and A. Montoya-Castillo for valuable discussions on the theory of polarons.
Funding:
This work was supported by the NSF Science and Technology Center on Real-Time Functional Imaging (STROBE) grant no. DMR-1548924 (R.W., B.L.E., and M.B.R.); U.S. Dept. of Education Graduate Assistance in Areas of National Need (L.A.H.); FWO International Mobility Program of the Flemish government (R.S.N.K.); and Publication of this article was funded by the University of Colorado Boulder Libraries Open Access Fund.
Ultrasonic spray coating of a gold nanoparticle-containing hole injection layer for optimized luminous efficacy in OLEDs
No full textPlasmon enhanced fluorescence from meticulously positioned gold nanoparticles, deposited by ultra sonic spray coating on organic light emitting diodes
No full textEnhancement of the spontaneous emission of fluorophores aided by plasmonic nanoparticles (PNPs) prompts the growth of plasmonic organic light emitting diodes (OLEDs). Together with the spatial dependence of the fluorophore and PNPs on enhanced fluorescence, the surface coverage of the PNPs controls the charge transport in OLEDs. Hence, here, the spatial and surface coverage reliance of plasmonic gold nanoparticles is controlled by a roll-to-roll compatible ultrasonic spray coating technique. A 2-fold enhancement in the multi photon fluorescence is seen by two-photon fluorescence microscopy for a polystyrene sulfonate (PSS) stabilized gold nanoparticle located 10 nm away from the super yellow fluorophore. Fluorescence enhancement combined with ∼2% surface coverage of PNPs, provides a 33%, 20% and ∼40% increase in the electroluminescence, luminous efficacy and external quantum efficiency, respectively.sponsorship: Universiteit Hasselt|BOF18NI05status: Publishe
Stretchable printed device for the simultaneous sensing of temperature and strain validated in a mouse wound healing model
Full text linkTemperature and strain are two vital parameters that play a significant role in wound diagnosis and healing. As periodic temperature measurements with a custom thermometer or strain measurements with conventional metallic gauges became less feasible for the modern competent health monitoring, individual temperature and strain measurement modalities incorporated into wearables and patches were developed. The proposed research in the article shows the development of a single sensor solution which can simultaneously measure both the above mentioned parameters. This work integrates a thermoelectric principle based temperature measurement approach into wearables, ensuring flexibility and bendability properties without affecting its thermo-generated voltage. The modified thermoelectric material helped to achieve stretchability of the sensor, thanks to its superior mechano-transduction properties. Moreover, the stretch-induced resistance changes become an additional marker for strain measurements so that both the parameters can be measured with the same sensor. Due to the independent measurement parameters (open circuit voltage and sensor resistance), the sensing model is greatly attractive for measurements without cross-sensitivity. The highly resilient temperature and strain sensor show excellent linearity, repeatability and good sensitivity. Besides, due to the compatibility of the fabrication scheme to low-temperature processing of the flexible materials and to mass volume production, printed fabrication methodologies were adopted to realize the sensor. This promises low-cost production and a disposable nature (single use) of the sensor patch. For the first time, this innovative temperature-strain dual parameter sensor concept has been tested on mice wounds in vivo. The preliminary experiments on mice wounds offer prospects for developing smart, i.e. sensorized, wound dressings for clinical applications
Design, synthesis, and photovoltaic performance of regioisomeric D18-Impact of cross-conjugation on electronic structure and solar cell efficiency
No full textThe unrivaled structural tunability of organic semiconductors allows to tailor their chemical and physical properties for distinct optoelectronic applications. This is particularly true for push-pull conjugated polymers, in which the (hetero)aromatic monomers, substituents, and side chains can be readily adapted. On the other hand, the impact of isomerization within the polymer backbone remains poorly explored. Here, a novel structural isomer of the state-of-the-art push-pull copolymer D18 is synthesized. This 'isoD18' regioisomer shows significantly different optical and electrochemical properties. Its deeper highest occupied molecular orbital energy level and reduced non-radiative voltage losses afford a higher open-circuit voltage (from 0.86 to 0.92 V) for the resulting polymer solar cells. Unfortunately, this is accompanied by a decrease in the short-circuit current density and fill factor, which can mainly be attributed to the one-order-lower hole mobility of isoD18, in line with its reduced thin-film organization. Although the performance of the devices based on the isomeric derivative turns out to be lower in this case, this study does enhance our insights into the effects of regioisomerism in polymer semiconductors on the resulting optoelectronic material and device features.The authors thank Huguette Penxten for the CV analysis and Prof. Anitha Ethirajan for access to the AFM equipment. They also thank the Research Foundation – Flanders (FWO Vlaanderen) for continuing financial support (PhD scholarship 1S98320N (Ka.V.), postdoctoral scholarships 1284623N (T.C.) and 1266923N (S.G.), MALDI‒ToF infrastructure project I006320N, and the Scientific Research Network ‘Supramolecular Chemistry and Materials’ W000620N), as well as the European Research Council (grant agreement 864625). Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02- 76SF00515
Electron-donating amine-interlayer induced n-type doping of polymer:nonfullerene blends for efficient narrowband near-infrared photo-detection
Full text linkInherently narrowband near-infrared organic photodetectors are highly desired for many applications, including biological imaging and surveillance. However, they suffer from a low photon-to-charge conversion efficiencies and utilize spectral narrowing techniques which strongly rely on the used material or on a nano-photonic device architecture. Here, we demonstrate a general and facile approach towards wavelength-selective near-infrared phtotodetection through intentionally n-doping 500–600 nm-thick nonfullerene blends. We show that an electron-donating amine-interlayer can induce n-doping, resulting in a localized electric field near the anode and selective collection of photo-generated carriers in this region. As only weakly absorbed photons reach this region, the devices have a narrowband response at wavelengths close to the absorption onset of the blends with a high spectral rejection ratio. These spectrally selective photodetectors exhibit zero-bias external quantum efficiencies of ~20–30% at wavelengths of 900–1100 nm, with a full-width-at-half-maximum of ≤50 nm, as well as detectivities of >10(12) Jones
Influence of thickness and annealing temperature of Polyethyleneimine ethoxylated on the luminous efficacy of Organic Light Emitting Diodes
No full textOrganic Light Emitting Diodes (OLED) with high luminous efficacy are one of the research topics that attract a lot of attention recently. To enhance luminous efficacy researchers have employed innumerable methods, materials and technologies. Amongst many materials available, polyethyleneimine ethoxylated (PEIE) as electron injection layer shows a promise as it is stable in ambient conditions and reduces the work-function of the contact electrode and lowers the injection current. However, the insulating nature of the PEIE prevails at the higher thickness and this reduces luminous efficacy. In the present work, the effect of various thickness of the PEIE layer at different annealing temperatures on the luminous efficacy is meticulously investigated.BOF fund of UHassel
Influence of thickness and annealing temperature of polyethylene amine ethoxylated on the luminous efficacy of organic light emitting diodes
No full textAbstract: Organic Light Emitting Diodes (OLED) with high luminous efficacy are one of the research topics that attract a lot of attention recently. To enhance luminous efficacy researchers have employed innumerable methods, materials and technologies. Amongst many materials available, polyethyleneimine ethoxylated (PEIE) as electron injection layer shows a promise as it is stable in ambient conditions and reduces the work-function of the contact electrode and lowers the injection current. However, the insulating nature of the PEIE prevails at the higher thickness and this reduces luminous efficacy. In the present work, the effect of various thickness of the PEIE layer at different annealing temperatures on the luminous efficacy is meticulously investigated.BOF fund of UHassel
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