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Modulating Crystallization in Semitransparent Perovskite Films Using Submicrometer Spongelike Polymer Colloid Particles to Improve Solar Cell Performance
摘要： Semitransparent perovskite solar cells (PSCs) have excellent potential for solar window applications. A major challenge exists, however, in achieving uniform coverage for thin perovskite films. Unfortunately, uncontrolled pinhole formation is a common problem for such films that obstructs development, especially for large area devices. In this study, we used very small (submicrometer) swellable polymer colloid particles (microgels) as additives to prepare uniform thin CH3NH3PbI3 (MAPI) perovskite films. Microgels (MGs) are good film-formers and promoted formation of semitransparent (ST) perovskite films with improved coverage. The MGs act as colloidal sponges and delayed release of perovskite precursors, thereby delaying perovskite crystallization. The ST films prepared using MGs had fewer pinholes compared to the MG-free control films. X-ray photoelectron spectroscopy showed evidence of Pb coordination by the MGs and they were shown to passivate MAPI. Remarkably, the submicrometer MGs used in this study decreased light scattering for the ST films. Planar devices constructed using a 10 nm ST film with an average visible transmittance of 46.8% gave an average power conversion efficiency (PCE) of 7.69%, which compares favorably to literature values. The average PCE increased to 9.62% upon inclusion of a thin meso-TiO2 layer. These PCE values are significantly higher than that achieved for the MG-free ST control (4.93%). The MGs and approaches used here are scalable and should apply to other ST perovskite films, solar cells, and, potentially, tandem devices.
关键词： Perovskite solar cell,semitransparent,crystallization,average visible transmittance,microgel
更新于2025-09-11 14:15:04
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Infrared reflectance, transmittance, and emittance spectra of MgO from first principles
摘要： By using density functional theory calculations we determined the influence of anharmonic effects on the infrared reflectance, transmittance, and emittance of MgO. The goal is to determine the limit of validity of a perturbative (multiphonon) approach. MgO is chosen as a test material because of the availability of different kinds of radiative properties measured experimentally. Nonanalytic terms of the three-phonon scattering coefficients are explicitly calculated and do not provide measurable effects. The agreement is overall very good to such an extent that, already at room temperature, one can clearly identify regions in which four-phonon scattering processes are dominant with respect to the three-phonon ones. The influence of isotopic disorder at cryogenic temperatures is also settled.
关键词： emittance,transmittance,density functional theory,MgO,infrared reflectance,anharmonic effects,phonon-phonon interactions
更新于2025-09-10 09:29:36
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Compensation of Oxygen Transmittance Effects for Proximal Sensing Retrieval of Canopy–Leaving Sun–Induced Chlorophyll Fluorescence
摘要： Estimates of Sun–Induced vegetation chlorophyll Fluorescence (SIF) using remote sensing techniques are commonly determined by exploiting solar and/or telluric absorption features. When SIF is retrieved in the strong oxygen (O2) absorption features, atmospheric effects must always be compensated. Whereas correction of atmospheric effects is a standard airborne or satellite data processing step, there is no consensus regarding whether it is required for SIF proximal–sensing measurements nor what is the best strategy to be followed. Thus, by using simulated data, this work provides a comprehensive analysis about how atmospheric effects impact SIF estimations on proximal sensing, regarding: (1) the sensor height above the vegetated canopy; (2) the SIF retrieval technique used, e.g., Fraunhofer Line Discriminator (FLD) family or Spectral Fitting Methods (SFM); and (3) the instrument's spectral resolution. We demonstrate that for proximal–sensing scenarios compensating for atmospheric effects by simply introducing the O2 transmittance function into the FLD or SFM formulations improves SIF estimations. However, these simplistic corrections still lead to inaccurate SIF estimations due to the multiplication of spectrally convolved atmospheric transfer functions with absorption features. Consequently, a more rigorous oxygen compensation strategy is proposed and assessed by following a classic airborne atmospheric correction scheme adapted to proximal sensing. This approach allows compensating for the O2 absorption effects and, at the same time, convolving the high spectral resolution data according to the corresponding Instrumental Spectral Response Function (ISRF) through the use of an atmospheric radiative transfer model. Finally, due to the key role of O2 absorption on the evaluated proximal–sensing SIF retrieval strategies, its dependency on surface pressure (p) and air temperature (T) was also assessed. As an example, we combined simulated spectral data with p and T measurements obtained for a one–year period in the Hyyti?l? Forestry Field Station in Finland. Of importance hereby is that seasonal dynamics in terms of T and p, if not appropriately considered as part of the retrieval strategy, can result in erroneous SIF seasonal trends that mimic those of known dynamics for temperature–dependent physiological responses of vegetation.
关键词： fraunhofer line discriminator (FLD),air temperature,spectral fitting method (SFM),atmospheric pressure,proximal sensing,O2 transmittance,sun–induced chlorophyll fluorescence (SIF)
更新于2025-09-10 09:29:36
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39.1: <i>Invited Paper:</i> Novel Photo-Alignment Material for Ultra-High Definition VA LCDs
摘要： Ultra-high definition vertically photo-aligned LC-displays inherently suffer from lower backlight transmittance. We proved, experimentally and by simulation, that the transmittance is increased by lowering the pre-tilt angle. Novel material based on Rolic’s proprietary photo-alignment technology yielding low pre- tilt angles and high reliability is developed and qualified for mass production by CEC Panda.
关键词： Pre-tilt,Photo-alignment,LCMO,LCD,Transmittance
更新于2025-09-10 09:29:36
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Significant Delay in the Detection of Desaturation between Finger Transmittance and Earlobe Reflectance Oximetry Probes during Fiberoptic Bronchoscopy: Analysis of 104 Cases
摘要： Purpose There is clinical significance to a delay in response time for detecting desaturation by pulse oximetry. Our aim in this study was to compare the response time of the reflectance and transmittance saturation probes during fiberoptic bronchoscopy (FOB) under monitored anesthesia care. Methods A prospective study included 104 patients scheduled for FOB. Patients were monitored with transmittance (finger) and reflectance (ear) oximetry probes. The response time was evaluated during desaturation and resaturation. We also acquired blood tests for arterial oxygen saturation to assess the agreement with the oximetry probes. Results Ninety patients had a desaturation episode during FOB and were included in the final analysis. Mean time difference between the reflectance ear probe (reference probe) and transmittance finger probe for the detection of desaturation (SpO2 = 90%) was + 36 s (CI 27.0–45.0, P < 0.001). The time difference between probes at end of desaturation episode (SpO2 = 95%) was + 31 s (CI 19.0–43.0; P < 0.001). A significant difference in response time was evident throughout the episode in all saturation values. The reflectance ear probe showed better agreement with arterial blood gases. The bias (and precision) for the earlobe and finger oximeters were of 0.24 (1.04) and 2.31 (3.37), respectively. Conclusion The data displayed by a centrally located reflectance probe are more accurate and allows for earlier identification, treatment, and resolution of desaturation events. In light of these data and the added value of the reflectance probe ability to measure transcutaneous PCO2, we recommend monitoring bronchoscopy by a reflectance oximetry probe.
关键词： Bronchoscopy,Delay,Reflectance,Oxygen saturation,Transmittance
更新于2025-09-10 09:29:36
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Durable, Optically Transparent, Superhydrophobic Polymer Films
摘要： Transparent and superhydrophobic free-standing films would be useful for extending non-wetting properties to optical applications especially those exposed to flowing water. However two challenges, transparency and durability, have proven difficult to overcome. Although a high degree of surface roughness is essential to sustain droplets of water in the Cassie state, this same roughness can lead to significant scattering and loss of optical clarity. Reducing roughness to a length scale below ? the wavelength of light reduces scattering, but can result in loss of durability. In this paper we describe a novel and simple lamination approach for treating free-standing films to become superhydrophobic, with high transparency and durability, by partially embedding hydrophobic silica nanoparticles into the surface of a cyclic olefin polymer (COP) film. Partial embedding insures that the particles are firmly adhered while their nano-scale roughness is exposed, resulting in excellent superhydrophobicity (contact angles >160° and roll off angle <10°), high transparency (over 87% transmission at 500 nm) and durability under flowing water (>6 hours at volumetric flow rate of 70 liters·min-1). The effect of processing parameters including the particle coating thickness and lamination conditions on the optical properties, hydrophobicity as well as mechanical durability of films are systematically studied.
关键词： wetting,optical transmittance,surface morphology,Superhydrophobicity,durability,lamination
更新于2025-09-10 09:29:36
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First Principle Study on Optical Properties of Tri-Group Doped (6,6) SiC Nanotubes
摘要： The optical properties of tri-group (B, Al, Ga, In) doped (6,6) SiC nanotubes (SiCNTs) are studied from first principles. The results show that the main absorption and dispersion of SiCNTs caused by the intrinsic transition appear in the ultraviolet-visible region (below 500 nm), and the tri-group doping increases the minimum dielectric constant value resulting in enhanced transmittance. In addition, the tri-group doping can introduce a weak absorption and dispersion region in the near-mid-infrared region, and the response peak blue shifts as the diameter of the doping atom increases. Comparative studies of reflectance, absorptivity, and transmittance show that the key factors affecting the transmittance of SiCNTs are reflectance (or refractive index) rather than absorption coefficient.
关键词： ultraviolet-visible region,SiC nanotubes,near-mid-infrared region,tri-group doped,optical properties,first principles,transmittance
更新于2025-09-10 09:29:36
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Growth of ZnSe nanowires on quartz substrates and their photomodulated transmittance spectra
摘要： ZnSe nanowires were grown on fused quartz substrates by a vapor transport method in which the ZnSe powder is heated at 1100?C in a tube of the furnace. The scanning electron microscopy images showed that the nanowires have the average diameter of ～110 nm. The X-ray di?raction measurement indicates that the ZnSe nanowires were a single phase of zinc-blende ZnSe. The photomodulated transmittance (PT) measurements were performed for the ZnSe nanowires at temperatures between 15 and 300 K. The measured PT spectra revealed distinct structures of E0 critical point at ～2.6?2.8 eV. This E0 critical point structure was successfully explained by adding an excitonic line shape to a one-electron line shape. The temperature dependence of E0 energy was analyzed using an analytical formula that takes into account the band-gap shrinkage e?ect by the electron-phonon interaction in semiconductors. The exciton binding energy of ZnSe nanowires was determined to be 20 meV.
关键词： Photomodulated transmittance,Crystal growth,ZnSe nanowires
更新于2025-09-10 09:29:36
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Enhancing optical absorption in visible light of ZnO co-doped with europium and promethium by first principles study through modified Becke and Johnson potential scheme
摘要： By using first-principle calculations we studied the electronic, optical and magnetic properties of ZnO co-doped with Eu and Pm. In this calculation, we used Wien2k code based on Full potential linearized augmented plane waves (FP-LAPW) method with the modified Becke-Johnson (mBJ) approximation. This correction gives good band gap compared to experimental band gap. The introduction of Eu and Pm codoping leads to an increase in the band gap. Electrons can transit easily from the valence band to the conduction band, which results in an enhancement of visible light absorption in a wider absorption range. Absorption spectra reach a high value in visible and infrared light regions. With the significance of the obtained results, the studied compounds may potentially find spintronic and optoelectronic applications.
关键词： transmittance,Zinc Oxide,density functional theory,band gap,spintronics,Rare Earth,magnetic properties,absorption,modified Becke-Johnson,photovoltaic
更新于2025-09-10 09:29:36
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Design and numerical analysis of a graphene-coated fiber-optic SPR biosensor using tungsten disulfide
摘要： This article provides a simple hybrid design and rigorous numerical analysis of a fiber optic–based surface plasmon resonance (SPR) biosensor for DNA hybridization. The sensor core and both sides of the cladding are constructed with optical fiber, whereas the middle portion of the cladding is filled with the proposed hybrid of silver, tungsten disulfide (WS2), graphene, and a sensing medium. To the best of our knowledge, this is the first demonstration of such a highly sensitive SPR biosensor using WS2 for sensing DNA hybridization. The sensitivity, detection accuracy, and figure of merit are considered as the performance parameters and are analyzed in detail. The analyses reveal an impressive enhancement of the overall performance of the proposed sensor. Insertion of a WS2 layer between silver and graphene provides a sensor with sensitivity higher than that of other sensors reported to date. Additionally, concurrent improvement of all performance parameters is shown by this hybrid sensor, which is not the case for sensors based only on graphene. An increased number of graphene-only layers increases the sensitivity and decreases the detection accuracy and figure of merit. Numerical analysis shows that the variation of the SPR angle for mismatched DNA strands is quite negligible, whereas that for complementary DNA strands is considerable, which is essential for proper detection of DNA hybridization. Therefore, the proposed biosensor opens a new window toward detection of biomolecular interactions.
关键词： DNA hybridization,transmittance,surface plasmon resonance angle,Biosensor,sensitivity,tungsten disulfide
更新于2025-09-09 09:28:46