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Development of Novel Mixed Halide/Superhalide Tin-Based Perovskites for Mesoscopic Carbon-Based Solar Cells
摘要： Tin perovskites suffer from poor stability and a self-doping effect. To solve this problem, we synthesized novel tin perovskites based on superhalide with varied ratios of tetrafluoroborate to iodide and implemented them into solar cells based on a mesoscopic carbon-electrode architecture because the film formation was an issue to apply this material for a planar heterojunction device structure. We undertook quantum-chemical calculations based on plane-wave density-functional-theory (DFT) methods and explored the structural and electronic properties of tin perovskites FASnI3-x(BF4)x in the series x = 0, 1, 2 and 3. We found that only the x = 2 case, FASnI(BF4)2, was successfully produced, beyond the standard FASnI3. The electrochemical impedance and X-ray photoelectron spectra indicate that the addition of tin tetrafluoroborate instead of SnI2 suppressed the trap-assisted recombination through decreasing the Sn4+ content. The efficiency of power conversion of the FASnI(BF4)2 device with FAI and Sn(BF4)2 in equimolar ratio improved 72 % relative to a standard FASnI3 solar cell, with satisfactory photostability under ambient air conditions.
关键词： DFT calculations,photostability,superhalide,tetrafluoroborate,solar cells,tin perovskites
更新于2025-09-19 17:13:59
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Effect of surface ligands with different terminal group on the optical stability and cytotoxicity of CuInS <sub/>2</sub> /ZnS quantum dots with the crystal structure of sphalerite
摘要： A novel method for preparing CuInS2/ZnS quantum dots (CuInS2/ZnS QDs) with the crystal structure of sphalerite by one-pot hot injection was developed in this paper. The as-prepared core CuInS2 quantum dots (CuInS2 QDs) was uniform spherical nanoparticle with the average diameter of about 2 nm with the ?uorescent quantum yields (QY) of about 2.6%. By capping a shell of ZnS on the surface of CuInS2 QDs, the formed CuInS2/ZnS QDs exhibited obvious enhanced ?uorescent emission with the QY of about 20%. Intriguingly, the crystal structure of obtained CuInS2/ZnS QDs is sphalerite, which was con?rmed by XRD. Considering the different terminal group between these small organic molecules, mercaptoacetic acid (TGA), thioglycerol (TGC) and mercaptoethylamine (MEA) were further selected as capping molecules to exchange the surface ligands of CuInS2/ZnS QDs. The obtained CuInS2/ZnS QDs modi?ed with TGC exhibited excellent photostability in physiological conditions. To investigate the effect of ligand molecules on the biocompatible of CuInS2/ZnS QDs, the experiment on the cytotoxicity of CuInS2/ZnS QDs to A549 cells were conducted. The results indicated that CuInS2/ZnS QDs capped with TGC showed the lowest cytotoxicity while CuInS2/ZnS QDs capped with MEA exhibited the highest cytotoxicity among the three types of CuInS2/ZnS QDs modi?ed with ligands with different terminal group. These results provided a sight on how to select surface ligands to modify CuInS2/ZnS QDs when CuInS2/ZnS QDs will apply in biological ?elds.
关键词： sphalerite,photostability,CuInS2/ZnS QDs,cytotoxicity,surface ligands
更新于2025-09-16 10:30:52
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Polymer dye laser pumped with green semiconductor lasers
摘要： We report the results of experiments on quasi-longitudinal pumping of a polymer dye laser by two green (λ = 513 nm) pulsed laser diodes. The lasing thresholds, efficiency, and photostability of pyrromethenes in various polymers are studied. The efficiency of dye lasers based on pyrromethene 567 and pyrromethene 580 with a three-mirror cavity with partial astigmatism compensation exceeds 20 %.
关键词： polymer dye laser,photostability,pyrromethenes,diode pumping
更新于2025-09-16 10:30:52
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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Efficient Two-Photon Luminescence for Bioimaging Using Polymer Conjugations of Graphene Quantum Dots Based Materials
摘要： In this study, examination results revealed that conjugated polymers containing nitrogen and sulfur atoms lead to a higher quantum confinement of emissive energy trapped on the surface of material (graphene quantum dot (GQD)-polymers), resulting in a high luminescence quantum yield and impressive two-photon properties. Additionally, the GQD-polymers generated nonreactive oxygen species-dependent oxidative stress on cells. Furthermore, we demonstrated the effective use of two-photon excitation-mediated high two-photon luminescence intensity in an acidic environment enabled GQD-polymers to act as a promising contrast probe. When cancer cells are labeled with specific antibody GQD-polymers conjugates, molecular-specific imaging can be performed deep into a tissue phantom with extremely high signal-to-noise ratios. In situations in which imaging depths are limited by the maximum available power that can be delivered to the three-dimensional (3D) bioimaging plane without causing damage to tissue, GQD-polymers might provide sufficient brightness to extend the maximum depth of imaging. Moreover, we demonstrated that the use of GQD-polymers can expand the capabilities of two-photon imaging to allow noninvasive 3D bioimaging of a variety of new molecular signatures.
关键词： photostability,reactive oxygen species,three-dimensional bioimaging,photodynamic therapy,two-photon excitation,contrast probe,graphene,quantum dot-polymer,two-photon luminescence,two-photon,contrast agent,nitrogen-doped graphene quantum dots
更新于2025-09-16 10:30:52
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Light-mediated effects of CdTe-MSA quantum dots on the autofluorescence of freshwater green microalgae: Spectroscopic studies
摘要： The water-soluble semiconductor quantum dots (QDs) serve as optically detectable models of nanoparticles and are commonly applied as photoluminescent markers in biological systems. The unicellular algae represent a popular model system suitable to evaluate pollution-induced effects. There is growing experimental evidence that release of metal ions cannot account for potential toxicity of metal containing nanoparticles, however, the underlying mechanisms are not clearly understood. Surrounding environment and illumination conditions are among the most important factors affecting the stability of QDs as well as the interaction between nanoparticles and cells such as microalgae. The measurements of changes in photoluminescence (PL) of QDs and autofluorescence (AF) of microalgae can thus be used as a non-invasive screening method for detecting mutual effects of nanoparticles and algae cells on each other under natural conditions. In this study, CdTe quantum dots (a peak of PL at 550 nm) capped with a mercaptosuccinic acid (MSA) were introduced into aqueous ionic medium containing wild type green freshwater microalgae Scenedesmus and Chlorella sp. cells under artificial and natural ambient illumination. The spectroscopy and microscopy techniques were applied to observe both the influence of the microalgae on the spectral properties of negatively charged CdTe-MSA quantum dots and the effects of nanoparticles on the microalgae. The presence of algae cells revealed a protecting effect on both medium-dependent and radiation-induced changes in photoluminescence properties of QDs, which could be related with the increased stability of the capping layer. The effects on cellular AF intensity and the interaction of QDs with cellular surface depended on type of microalgae. The observed changes in AF spectral properties and AF induction signals can’t be explained only by the photodegradation of QDs and have revealed the ability of nanoparticles to retard the photoadaptation of wild type microalgae under naturally varying illumination conditions.
关键词： photostability,quantum dots,photoluminescence,green microalgae,photoadaptation
更新于2025-09-12 10:27:22
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Synthesis of Perovskite CsPbBr <sub/>3</sub> Quantum Dots/Porous Boron Nitride Nanofiber Composites with Improved Stability and Their Reversible Optical Response to Ammonia
摘要： All-inorganic CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) have great potential for various applications due to their excellent photoluminescence properties. However, poor stability under long-term storage hinders their applications. Herein we report the utilization of porous boron nitride nanofibers (BNNFs) as a promising carrier for anchoring of CsPbBr3 QDs. Due to the good dispersion and immobilization of CsPbBr3 QDs, the resulting CsPbBr3/BNNF composites show excellent photostability and superior long-term storage stability in an air environment. Moreover, the CsPbBr3/BNNF composites exhibit an interesting ammonia-responsive behavior: i.e., a distinct decrease in photoluminescence intensity upon exposure to ammonia gas and the subsequent photoluminescence recovery after post-treatment in nitrogen gas. Even after treatment with ammonia gas for 3 h, the composites can still be recovered under nitrogen gas treatment. The fast response, reversibility, and stability of CsPbBr3/BNNF composites in the presence of ammonia gas could inspire a broader range of applications.
关键词： photostability,reversible optical response,perovskite quantum dots,boron nitride nanofibers,ammonia-responsive behavior
更新于2025-09-12 10:27:22
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Highly-Crystalline Near-Infrared Acceptor Enabling Simultaneous Efficiency and Photostability Boosting in High-Performance Ternary Organic Solar Cells
摘要： The near-infrared (NIR) absorbing fused-ring electron acceptor, COi8DFIC, has demonstrated very good photovoltaic performance when combined with PTB7-Th as donor in binary organic solar cells (OSCs). In this work, the NIR acceptor was added to state-of-the art PBDB-T-2F:IT-4F-based solar cells as a third component, leading to: (i) an efficiency increase of the ternary devices compared to the binary solar cells in the presence of the highly-crystalline COi8DFIC acceptor and (ii) much improved photostability under 1-sun illumination. The electron transport properties were investigated and revealed the origin of the enhanced device performance. Compared to the binary cells, the optimized ternary PBDB-T-2F:COi8DFIC:IT-4F blends exhibit improved electron transport properties in the presence of 10% COi8DFIC, which is attributed to improved COi8DFIC molecular packing. Furthermore, transient absorption spectroscopy revealed slow recombination of charge carriers in the ternary blend. The improved electron transport properties were preserved in the ternary OSC upon aging, while in the binary devices they seriously deteriorated after simulated 1-sun illumination of 240 hours. Our work demonstrates a simple approach to enhance both OSC efficiency and photostability.
关键词： near-infrared acceptor,organic solar cell,ternary solar cell,photostability
更新于2025-09-12 10:27:22
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Enhanced Lifetime and Photostability with Low‐temperature Mesoporous ZnTiO3/Compact SnO2 Electrodes in Perovskite Solar Cells
摘要： Perovskite solar cells (PSC) which have exceeded power conversion efficiencies (PCEs) of 25% are mainly demonstrated by using SnO2 or TiO2 as electron-transporting layers (ETLs). However, high-performance planar PSCs need precise process, which is difficult for large-scale production. Mesoporous structure shows better operability but with high-temperature process. Besides, as the most used mesoporous materials, the strong photocatalytic effect of TiO2 significantly limits the practical stability of PSCs under illumination (including ultraviolet light). Here we propose Zinc Titanate (ZnTiO3, ZTO) as mesoporous ETLs due to its weak photo-effect, excellent carrier extraction and transfer properties. Uniform mesoporous films were obtained by spinning coating the ZTO ink and annealed below 150°C. Photovoltaic devices based on Cs0.05FA0.81MA0.14PbI2.55Br0.45 perovskite sandwiched between SnO2-mesorporous ZTO electrode and Spiro-OMeTAD layer achieved the PCE of 20.5%. The PSCs retained more than 95% of their original efficiency after 100 days lifetime test without being encapsulated. Additionally, the PSCs retained over 95% of the initial performance when subjected at the maximum power point voltage for 120 h under AM 1.5G illumination (100 mW cm-2), demonstrating superior working stability. The application of ZTO provides a better choice for ETLs of PSCs. Moreover, the low temperature deposition method of inorganic ETL furnishes a way of low power consumption, large-scale and flexible preparation of PSCs.
关键词： perovskite solar cell,mesoporous ETL,photostability,ZTO,low-temperature
更新于2025-09-11 14:15:04
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1 cm <sup>2</sup> Organic Photovoltaic Cells for Indoor Application with over 20% Efficiency
摘要： Organic photovoltaic (OPV) technologies have the advantages of fabricating larger-area and light-weight solar panels on flexible substrates by low-cost roll-to-toll production. Recently, OPV cells have achieved many significant advances with power conversion efficiency (PCE) increasing rapidly. However, large-scale solar farms using OPV modules still face great challenges, such as device stability. Herein, the applications of OPV cells in indoor light environments are studied. Via optimizing the active layers to have a good match with the indoor light source, 1 cm2 OPV cells are fabricated and a top PCE of 22% under 1000 lux light-emitting diode (2700 K) illumination is demonstrated. In this work, the light intensities are measured carefully. Incorporated with the external quantum efficiency and photon flux spectrum, the integral current densities of the cells are calculated to confirm the reliability of the photovoltaic measurement. In addition, the devices show much better stability under continuous indoor light illumination. The results suggest that designing wide-bandgap active materials to meet the requirements for the indoor OPV cells has a great potential in achieving higher photovoltaic performance.
关键词： indoor application,power conversion efficiency,organic photovoltaic cells,photostability
更新于2025-09-11 14:15:04
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Molecular origin of photostability for fluorene-based donor–acceptor type photovoltaic polymers
摘要： Quantitative analyses of photodegradation for three fluorene-based photovoltaic polymers, poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)] (APFO3), polyfluorene (PFO), and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were conducted to understand the molecular origin of photostability for polymers. The Fourier transform infrared (FT-IR) spectra of polymer thin-films varied by irradiating white light at 100 mW?cm-2 irrespective of their molecular architectures. The absorption peaks corresponding to alkyl side chains in a fluorene unit decreased, whereas those for polymers that did not comprise carbonyl groups increased. This spectral variation indicates that alkyl side chains in the fluorene unit decompose when the molecular structure of fluorene varies to that of fluorenone. The reaction rate constant of formation of C=O bond for APFO3 was 1.64×10-5 s-1, lower than PFO (7.59×10-5 s-1) and F8BT (2.64×10-5 s-1), under light irradiation at 30 ?C. The photostability of the polymers improves by designing a donor–acceptor type molecular architecture—incorporating photostable electron deficient benzothiadiazole units with photo-unstable fluorene units.
关键词： fluorene-based,photostability,FT-IR,donor–acceptor,UV-vis,photovoltaic polymers
更新于2025-09-11 14:15:04