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Distinct metabolic profiles in Drosophila sperm and somatic tissues revealed by two-photon NAD(P)H and FAD autofluorescence lifetime imaging
摘要： Metabolic profiles vary across all levels of biological diversity, from cells to taxa. Two-photon fluorescence lifetime imaging microscopy (FLIM) facilitates metabolic characterisation of biological specimens by assaying the intrinsic autofluorescence of the ubiquitous coenzymes NAD(P)H and FAD. the potential of this method for characterising the diversity of organismal metabolism remains largely untapped. Using FLIM in Drosophila melanogaster, we show tissue-specificity in fluorescence lifetime that reflects variation in redox patterns. In particular, sperm cells exhibited elevated glycolysis relative to other tissues. We also show that sperm metabolism is phenotypically plastic: compared to male-stored sperm, sperm stored in the female’s storage organ showed a substantial reduction in the protein-bound FAD lifetime fraction but no change in the NAD(P)H profile. This study represents the first ex vivo investigation of sperm metabolism using FLIM.
关键词： two-photon fluorescence lifetime imaging microscopy,FAD,Drosophila melanogaster,NAD(P)H,glycolysis,sperm metabolism,OxPHOS
更新于2025-09-12 10:27:22
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Intrinsically stable organic solar cells under high-intensity illumination
摘要： Organic photovoltaic cells are now approaching commercially viable efficiencies, particularly for applications that make use of their unique potential for flexibility and semitransparency1–3. However, their reliability remains a major concern, as even the most stable devices reported so far degrade within only a few years4–8. This has led to the belief that short operational lifetimes are an intrinsic disadvantage of devices that are fabricated using weakly bonded organic materials—an idea that persists despite the rapid growth and acceptance of organic light-emitting devices, which can achieve lifetimes of several million hours9. Here we study an extremely stable class of thermally evaporated single-junction organic photovoltaic cells. We accelerated the ageing process by exposing the packaged cells to white-light illumination intensities of up to 37 Suns. The cells maintained more than 87 per cent of their starting efficiency after exposure for more than 68 days. The degradation rate increases superlinearly with intensity, leading to an extrapolated intrinsic lifetime, T80, of more than 4.9 × 107 hours, where T80 is the time taken for the power conversion efficiency to decrease to 80 per cent of its initial value. This is equivalent to 27,000 years outdoors. Additionally, we subjected a second group of organic photovoltaic cells to 20 Suns of ultraviolet illumination (centred at 365 nanometres) for 848 hours, a dose that would take 1.7 × 104 hours (9.3 years) to accumulate outdoors. No efficiency loss was observed over the duration of the test. Overall, we find that organic solar cells packaged in an inert atmosphere can be extremely stable, which is promising for their future use as a practical energy-generation technology.
关键词： energy-generation technology,stability,organic photovoltaic cells,lifetime,high-intensity illumination
更新于2025-09-11 14:15:04
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Effective minority carrier lifetime as an indicator for potential-induced degradation in p-type single-crystalline silicon photovoltaic modules
摘要： In this paper, we report the effective minority carrier lifetime (τeff) in fresh and potential-induced degradation (PID) acceleration tested p-type single-crystalline Si modules. τeff in different regions of solar cells was measured using the microwave photoconductance decay (μPCD) method. Electroluminescence (EL), lock-in-thermography, and dark and light current–voltage (I–V ) measurements were carried out as a complementary analysis of μPCD. In addition, τeff in every stage of Si solar cell fabrication (wafer to solar cell) was measured to investigate the change of carrier dynamics. From the obtained results, a great decrease in τeff was observed in the PID-affected regions, confirming the excess non-radiative recombination centers in that region, suggesting that τeff from the μ-PCD method can be an effective indicator to judge whether PID phenomenon has occurred.
关键词： microwave photoconductance decay,p-type single-crystalline silicon,potential-induced degradation,effective minority carrier lifetime,photovoltaic modules
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Low-temperature silicon surface passivation for bulk lifetime studies based on Corona-charged Al2O3
摘要： Bulk lifetime studies of crystalline silicon wafers, e.g. with the aim of studying the light-induced degradation and regeneration behavior, require low-temperature surface passivation schemes that do not alter the silicon bulk properties, e.g. through hydrogenation. Aluminum oxide (Al2O3) can provide an excellent and stable surface passivation, however, in order to achieve the best possible surface passivation, an annealing step at ~400°C is typically required, which has been found to alter the bulk properties of some silicon materials. Hence, in this contribution we examine the possibility of passivating the silicon surface using Al2O3 layers that have seen a much lower thermal budget. We demonstrate that we are able to achieve an excellent silicon surface passivation using atomic-layer-deposited Al2O3 with measured effective surface recombination velocities Seff as low as 1.3 cm/s without exceeding a temperature of 250°C. We are able to achieve such excellent low-temperature passivation by applying a post-deposition annealing step at 250°C in combination with the deposition of negative Corona charges on the Al2O3 surface. For samples annealed at only 220°C, we still reach very low Seff values of 2 cm/s after deposition of negative Corona charges. We demonstrate that the Corona-charged low-temperature Al2O3 passivation shows only a slight degradation from an Seff of 1.6 cm/s to an Seff of 5 cm/s after 218 days of storage. Even without any post-deposition anneal and only negative Corona charges deposited, we achieve stable Seff values of 15 cm/s. As an alternative to Corona charging, a short exposure to intense UV light (λ = 395 nm) also significantly improves the surface passivation quality of low-temperature-annealed Al2O3-passivated silicon samples. However, the best surface passivation for the latter method is limited to an Seff value of 6.6 cm/s, which is still quite reasonable for bulk lifetime studies.
关键词： bulk lifetime studies,Al2O3,Corona charging,silicon surface passivation,low-temperature annealing
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 9th International Nanoelectronics Conferences (INEC) - Kuching, Malaysia (2019.7.3-2019.7.5)] 2019 IEEE 9th International Nanoelectronics Conferences (INEC) - Dependence of operating conditions on lifetime of Phosphor Quantum dots-based white LEDs
摘要： Lifetime of packaged Phosphor- Quantum dot (QDs) based white LEDs is studied. Various stress parameters such as blue light luminance, temperature and moisture are considered and their effect on the performance of the Phosphor- QD based LED is investigated. The lumen degradation rate and degradation trend for LEDs is observed to be different under varying stress conditions. Lumen recovery process is also observed under light stress test.
关键词： down conversion,Light emitting diodes,Quantum dot,lifetime,Phosphor
更新于2025-09-11 14:15:04
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Mission Profile-Oriented Control for Reliability and Lifetime of Photovoltaic Inverters
摘要： With the aim to increase the competitiveness of solar energy, the high reliability of Photovoltaic (PV) inverters is demanded. In PV applications, the inverter reliability and lifetime are strongly affected by the operating condition that is referred to as the mission profile (i.e., solar irradiance and ambient temperature). Since the mission profile of PV systems is location-dependent, the inverter reliability performance and lifetime can vary considerably in practice. That is, from the reliability perspective, PV inverters with the same design metrics (e.g., component selection) may become over- or under-designed under different mission profiles. This will increase the overall system cost, e.g., initial cost for over-designed cases and maintenance cost for under-designed cases, which should be avoided. This paper thus explores the possibility to adapt the control strategies of PV inverters to the corresponding mission profiles. With this, similar reliability targets (e.g., component lifetime) can be achieved even under different mission profiles. Case studies have been carried out on PV systems installed in Denmark and Arizona, where the lifetime and the energy yield are evaluated. The results reveal that the inverter reliability can be improved by selecting a proper control strategy according to the mission profile.
关键词： capacitor,reliability,lifetime,PV inverters,mission profile,power device,control
更新于2025-09-11 14:15:04
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Reliability Characterization and Modelling of High Speed Ge Photodetectors
摘要： Understanding the origin and protocols to induce performance degradations of silicon photonics high speed photodetector represent a major issue for the qualification of the reliability of these devices. Using advanced characterization technics, it is shown that the dark current, the photonic current and the cut-off frequency of the photodiode can be degraded during voltage stress of 106 s, which could ultimately induce some significant device performance drift and failure. An explanation of these degradations is presented based on both electrical observed characterization degradations of both dark current and responsivity can indeed be modeled by a single carrier lifetime degradation, attributed to an impacting an increase of the surface recombination rate, unexpected in the this model are photocurrent. The results obtained with experimentally confirmed by extracting the activation energy of the dark current, before and after stress. The improved physical understanding of the degradation is expected to lead to shorter test protocols for silicon photonics devices.
关键词： carrier lifetime electrical characterization,Silicon photonics,activation energy,Ge photodetectors reliability
更新于2025-09-11 14:15:04
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A Quantum Dot-Based FLIM Glucose Nanosensor
摘要： In the last few years, quantum dot (QD) nanoparticles have been employed for bioimaging and sensing due to their excellent optical features. Most studies have used photoluminescence (PL) intensity-based techniques, which have some drawbacks, especially when working with nanoparticles in intracellular media, such as fluctuations in the excitation power, fluorophore concentration dependence, or interference from cell autofluorescence. Some of those limitations can be overcome with the use of time-resolved spectroscopy and fluorescence lifetime imaging microscopy (FLIM) techniques. In this work, CdSe/ZnS QDs with long decay times were modified with aminophenylboronic acid (APBA) to achieve QD-APBA conjugates, which can act as glucose nanosensors. The attachment of the boronic acid moiety on the surface of the nanoparticle quenched the PL average lifetime of the QDs. When glucose bonded to the boronic acid, the PL was recovered and its lifetime was enhanced. The nanosensors were satisfactorily applied to the detection of glucose into MDA-MB-231 cells with FLIM. The long PL lifetimes of the QD nanoparticles made them easily discernible from cell autofluorescence, thereby improving selectivity in their sensing applications. Since the intracellular levels of glucose are related to the metabolic status of cancer cells, the proposed nanosensors could potentially be used in cancer diagnosis.
关键词： fluorescence lifetime imaging,intracellular sensing,quantum dots,nanoparticles,glucose,photoluminescence
更新于2025-09-11 14:15:04
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Unveiling the Root Cause of the Efficiency-Lifetime Trade-Off in Blue Fluorescent Organic Light-Emitting Diodes
摘要： The origin of efficiency-lifetime trade-off in triplet–triplet fusion (TTF) type blue fluorescent organic light-emitting diodes (OLEDs) was investigated and the device structure to resolve the issue was developed. The efficiency and lifetime were simultaneously improved in the blue OLEDs by developing a multilayer hole transport stack which can adjust carrier densities and recombination zone in the emitting layer (EML). It was found that electron leakage from EML and high spatial density of excitons in the vicinity of the electron blocking layer for high TTF rates by narrow recombination zone are the detrimental factors for efficiency-lifetime trade-off. A multilayer hole transport stack employing a deep highest occupied molecular orbital hole transport layer and an electron blocking layer combined with an appropriate hole blocking layer simultaneously improved the power efficiency by 16% at 500 cd/m2 and lifetime by almost 100% (from 73 h up to 145 h). In addition, the low efficiency in the low luminance region was also completely controlled, resulting in negligible efficiency variation in the entire luminance range.
关键词： Efficiency-lifetime trade off,Blue fluorescent OLEDs,Triplet–triplet fusion
更新于2025-09-11 14:15:04
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Investigation on Spectroscopic and Laser Properties of Pyrromethene and Perylene Chromophores in Elastic Polymeric Hosts
摘要： In this work, two types of chromophore i.e. the pyrromethene and perylene families dyes were doped into elastic polymeric host materials based on polydimethylsiloxane (PDMS), which had been widely employed in various applications. The solubilities, spectroscopic and laser properties of these dyes doped into PDMS matrices were systematically investigated. Tunable laser output with high conversion efficiencies and low laser thresholds were observed and calculated. The laser longevity of pyrromethene dyes doped in PDMS matrices could exceed 1 (cid:2) 105 pulses through a fast self-recovery on the laser output with the elapse of aging time. The efficient and stable laser output of the dopants and the flexibility of the PDMS host provided the feasibility of such gain media as mechanically tunable laser sources, which might be employed as cost-effective components on integrated bio-chips.
关键词： Polydimethylsiloxane (PDMS),Laser lifetime,Self-recovery,Dyes,Laser chemistry
更新于2025-09-11 14:15:04