Broadband Superabsorber Operating at 1500 °C Using Dielectric Bilayers.

Many technological applications in photonics require devices to function reliably under extreme conditions, including high temperatures. To this end, materials and structures with thermally stable optical properties are indispensable. State-of-the-art thermal photonic devices based on nanostructures suffer from severe surface diffusion-induced degradation, and the operational temperatures are often restricted. Here, we report on a thermo-optically stable superabsorber composed of bilayer refractory dielectric materials. The device features an average absorptivity ∼95% over >500 nm bandwidth in the near-infrared regime, with minimal temperature dependence up to 1500 °C. Our results demonstrate an alternative pathway to achieve high-temperature thermo-optically stable photonic devices.

Scalable Superabsorbers and Color Filters Based on Earth-Abundant Materials.

Optical materials based on unconventional plasmonic metals (e.g., magnesium) have lately driven rising research interest for the quest of possibilities in nanophotonic applications. Several favorable attributes of Mg, such as earth abundancy, lightweight, biocompatibility/biodegradability, and its active reactions with water or hydrogen, have underpinned its emergence as an alternative nanophotonic material. Here, we experimentally demonstrate a thin film-based optical device composed exclusively of earth-abundant and complementary metal-oxide semiconductor (CMOS)-compatible materials (i.e., Mg, a-Si, and SiO2). The devices can exhibit a spectrally selective and tunable near-unity resonant absorption with an ultrathin a-Si absorbing layer due to the strong interference effect in this high-index and lossy film. Alternatively, they can generate diverse reflective colors by appropriate tuning of the a-Si and SiO2 layer thicknesses, including all the primary colors for RGB (red, green, blue) and CMY (cyan, magenta, yellow) color spaces. In addition, the reflective hues of the devices can be notably altered in a zero power-consumption fashion by immersing them in water due to the resulted dissolution of the Mg back-reflection layer. These compelling features in combination with the lithography-free and scalable fabrication steps may promise their adoption in various photonic applications including solar energy harvesting, optical information security, optical modulation, and filtering as well as structure reuse and recycling.

Machine Learning Enables Prediction of Halide Perovskites' Optical Behavior with >90% Accuracy.

The composition-dependent degradation of hybrid organic-inorganic perovskites (HOIPs) due to environmental stressors still precludes their commercialization. It is very difficult to quantify their behavior upon exposure to each stressor by exclusively using trial-and-error methods due to the high-dimensional parameter space involved. We implement machine learning (ML) models using high-throughput, in situ photoluminescence (PL) to predict the response of Cs y FA1-y Pb(Br x I1-x )3 while exposed to relative humidity cycles. We quantitatively compare three ML models while generating forecasts of environment-dependent PL responses: linear regression, echo state network, and seasonal autoregressive integrated moving average with exogenous regressor algorithms. We achieve accuracy of >90% for the latter, while tracking PL changes over a 50 h window. Samples with 17% of Cs content consistently showed a PL increase as a function of cycle. Our precise time-series forecasts can be extended to other HOIP families, illustrating the potential of data-centric approaches to accelerate material development for clean-energy devices.

Optical Tunability and Characterization of Mg-Al, Mg-Ti, and Mg-Ni Alloy Hydrides for Dynamic Color Switching Devices.

Mg shows great potential as a metal hydride for switchable optical response and hydrogen detection due to its ability to stably incorporate significant amounts of hydrogen into its lattice. However, this thermodynamic stability makes hydrogen removal difficult. By alloying Mg with secondary elements, the hydrogenation kinetics can be increased. Here, we report the dynamic optical, loading, and stress properties of three Mg alloy systems (Mg-Al, Mg-Ti, and Mg-Ni) and present several novel phenomena and three distinct device designs that can be achieved with them. We find that these materials all have large deviations in refractive index when exposed to H2 gas, with a wide range of potential properties in the hydride state. The magnitude and sign of the optical property change for each of the alloys are similar, but the differences have dramatic effects on device design. We show that Mg-Ti alloys perform well as both switchable windows and broadband switchable light absorbers, where Mg0.87Ti0.13 and Mg0.85Ti0.15 can achieve a 40% transmission change as a switchable window and a 55% absorption change as a switchable solar absorber. We also show how different alloys can be used for dynamically tunable color filters, where both the reflected and transmitted colors depend on the hydrogenation state. We demonstrate how small changes in the alloy composition (e.g., with Mg-Ni) can lead to dramatically different color responses upon hydrogenation (red-shifting vs blue-shifting of the resonance). Our results establish the potential for these Mg alloys in a variety of applications relating to hydrogen storage, detection, and optical devices, which are necessary for a future hydrogen economy.

Refractory Metals and Oxides for High-Temperature Structural Color Filters.

Refractory metals have recently garnered significant interest as options for photonic applications due to their superior high-temperature stability and versatile optical properties. However, most previous studies only consider their room-temperature optical properties when analyzing these materials' behavior as optical components. Here, we demonstrate structural color pixels based on three refractory metals (Ru, Ta, and W) for high-temperature applications. We quantify their optical behavior in an oxygenated environment and determine their dielectric functions after heating up to 600 °C. We use in situ oxidation, a fundamental chemical reaction, to form nanometer-scale metal oxide thin-film bilayers on each refractory metal. We fully characterize the behavior of the newly formed thin-film interference structures, which exhibit vibrant color changes upon high-temperature treatment. Finally, we present optical simulations showing the full range of hues achievable with a simple two-layer metal oxide/metal reflector structure. All of these materials have melting points >1100 °C, with the Ta-based structure offering high-temperature stability, and the Ru- and W-based options providing an alternative for reversible color filters, at high temperatures in inert or vacuum environments. Our approach is uniquely suitable for high-temperature photonics, where the oxides can be used as conformal coatings to produce a wide variety of colors across a large portion of the color gamut.

Is Mallampati classification a good screening test? A prospective cohort evaluating the predictive values of Mallampati test at different thresholds

Abstract Background There is currently some discussion over the actual usefulness of performing preoperative upper airway assessment to predict difficult airways. In this field, modified Mallampati test (MMT) is a widespread tool used for prediction of difficult airways showing only a feeble predictive performance as a diagnostic test. We therefore aimed at evaluating if MMT test would perform better when used as a screening test rather than diagnostic. Methods An accuracy prospective study was conducted with 570 patients undergoing general anesthesia for surgical procedures. We collected preoperatively data on sex, age, weight, height, body mass index (BMI), ASA physical status, and MMT. The main outcome was difficult laryngoscopy defined as Cormack and Lahane classes 3 or 4. Bivariate analyses were performed to build three different predictive models with their ROC curves. Results Difficult laryngoscopy was reported in 36 patients (6.32%). Sex, ASA physical status, and MMT were associated with difficult laryngoscopy, while body mass index (BMI) was not. The MMT cut-off with the highest odds ratio was the class II, which also presented significantly higher sensitivity (94.44%). The balanced accuracy was 67.11% (95% CI: 62.78-71.44%) for the cut-off of class II and 71.68% (95% CI: 63.83-79.54) for the class III. Conclusion MMT seems to be more clinically useful when the class II is employed as the threshold for possible difficult laryngoscopies. At this cut-off, MMT shows the considerable highest sensitivity plus the highest odds ratio, prioritizing thus the anticipation of difficult laryngoscopies.

Quantitative Predictions of Moisture-Driven Photoemission Dynamics in Metal Halide Perovskites via Machine Learning.

Metal halide perovskite (MHP) photovoltaics may become a viable alternative to standard Si-based technologies, but the current lack of long-term stability precludes their commercial adoption. Exposure to standard operational stressors (light, temperature, bias, oxygen, and water) often instigate optical and electronic dynamics, calling for a systematic investigation into MHP photophysical processes and the development of quantitative models for their prediction. We resolve the moisture-driven light emission dynamics for both methylammonium lead tribromide and triiodide thin films as a function of relative humidity (rH). With the humidity and photoluminescence time series, we train recurrent neural networks and establish their ability to quantitatively predict the path of future light emission with 18% error over 4 h. Together, our in situ rH-PL measurements and machine learning forecasting models provide a framework for the rational design of future stable perovskite devices and, thus, a faster transition toward commercial applications.

Is Mallampati classification a good screening test? A prospective cohort evaluating the predictive values of Mallampati test at different thresholds.

BACKGROUND: There is currently some discussion over the actual usefulness of performing preoperative upper airway assessment to predict difficult airways. In this field, modified Mallampati test (MMT) is a widespread tool used for prediction of difficult airways showing only a feeble predictive performance as a diagnostic test. We therefore aimed at evaluating if MMT test would perform better when used as a screening test rather than diagnostic. METHODS: An accuracy prospective study was conducted with 570 patients undergoing general anesthesia for surgical procedures. We collected preoperatively data on sex, age, weight, height, body mass index (BMI), ASA physical status, and MMT. The main outcome was difficult laryngoscopy defined as Cormack and Lahane classes 3 or 4. Bivariate analyses were performed to build three different predictive models with their ROC curves. RESULTS: Difficult laryngoscopy was reported in 36 patients (6.32%). Sex, ASA physical status, and MMT were associated with difficult laryngoscopy, while body mass index (BMI) was not. The MMT cut-off with the highest odds ratio was the class II, which also presented significantly higher sensitivity (94.44%). The balanced accuracy was 67.11% (95% CI: 62.78...71.44%) for the cut-off of class II and 71.68% (95% CI: 63.83...79.54) for the class III. CONCLUSION: MMT seems to be more clinically useful when the class II is employed as the threshold for possible difficult laryngoscopies. At this cut-off, MMT shows the considerable highest sensitivity plus the highest odds ratio, prioritizing thus the anticipation of difficult laryngoscopies.

Machine Learning Roadmap for Perovskite Photovoltaics.

Perovskite solar cells (PSC) are a favorable candidate for next-generation solar systems with efficiencies comparable to Si photovoltaics, but their long-term stability must be proven prior to commercialization. However, traditional trial-and-error approaches to PSC screening, development, and stability testing are slow and labor-intensive. In this Perspective, we present a survey of how machine learning (ML) and autonomous experimentation provide additional toolkits to gain physical understanding while accelerating practical device advancement. We propose a roadmap for applying ML to PSC research at all stages of design (compositional selection, perovskite material synthesis and testing, and full device evaluation). We also provide an overview of relevant concepts and baseline models that apply ML to diverse materials problems, demonstrating its broad relevance while highlighting promising research directions and associated challenges. Finally, we discuss our outlook for an integrated pipeline that encompasses all design stages and presents a path to commercialization.

Control of hot-carrier relaxation time in Au-Ag thin films through alloying.

The plasmon resonance of a structure is primarily dictated by its optical properties and geometry, which can be modified to enable hot-carrier photodetectors with superior performance. Recently, metal alloys have played a prominent role in tuning the resonance of plasmonic structures through chemical composition engineering. However, it has been unclear how alloying modifies the time dynamics of the generated hot-carriers. In this work, we elucidate the role of chemical composition on the relaxation time of hot-carriers for the archetypal AuxAg1-x thin film system. Through time-resolved optical spectroscopy measurements in the visible wavelength range, we measure composition-dependent relaxation times that vary up to 8× for constant pump fluency. Surprisingly, we find that the addition of 2% of Ag into Au films can increase the hot-carrier lifetime by approximately 35% under fixed fluence, as a result of a decrease in optical loss. Further, the relaxation time is found to be inversely proportional to the imaginary part of the permittivity. Our results indicate that alloying is a promising approach to effectively control hot-carrier relaxation time in metals.

In Situ Optical and Stress Characterization of Alloyed PdxAu1-x Hydrides.

PdxAu1-x alloys have recently shown great promise for next-generation optical hydrogen sensors due to their increased chemical durability while their optical sensitivity to small amounts of hydrogen gas is maintained. However, the correlation between chemical composition and the dynamic optical behavior upon hydrogenation/dehydrogenation is currently not well understood. A complete understanding of this relation is necessary to optimize future sensors and nanophotonic devices. Here, we quantify the dynamic optical, chemical, and mechanical properties of thin film PdxAu1-x alloys as they are exposed to H2 by combining in situ ellipsometry with gravimetric and stress measurements. We demonstrate the dynamic optical property dependence of the film upon hydrogenation and directly correlate it with the hydrogen content up to a maximum of 7 bar of H2. With this measurement, we find that the thin films exhibit their strongest optical sensitivity to H2 in the near-infrared. We also discover higher hydrogen-loading amounts as compared to previous measurements for alloys with low atomic percent Pd. Specifically, a measurable optical and gravimetric hydrogen response in alloys as low as 34% Pd is found, when previous works have suggested a disappearance of this response near 55% Pd. This result suggests that differences in film stress and microstructuring play a crucial role in the sorption behavior. We directly measure the thin film stress and morphology upon hydrogenation and show that the alloys have a substantially higher relative stress change than pure Pd, with the pure Pd data point falling 0.9 GPa below the expected trend line. Finally, we use the measured optical properties to illustrate the applicability of these alloys as grating structures and as a planar physical encryption scheme, where we show significant and variable changes in reflectivity upon hydrogenation. These results lay the foundation for the composition and design of next-generation hydrogen sensors and tunable photonic devices.

Alloying: A Platform for Metallic Materials with On-Demand Optical Response.

Metallic materials with engineered optical properties have the potential to enhance the performance of energy harvesting and storage devices operating at the macro- and nanoscale, such as solar cells, photocatalysts, water splitting, and hydrogen storage systems. For both thin films and subwavelength nanostructures, upon illumination, the coherent oscillation of charge carriers at the interface with a dielectric material gives rise to resonances named surface plasmon polariton (SPP) and localized surface plasmon resonance (LSPR), respectively. These resonances result in unique light absorption, scattering, and transmission responses over the electromagnetic spectrum, which, in turn, can be exploited to tailor the behavior of active metallic components in optoelectronic devices containing Ag, Au, Cu, Al, Mg, among other metals. The wavelength in which the resonances occur primarily depends on the metal itself (i.e., the dielectric function or permittivity), the dielectric medium surrounding the metals, and the size, geometry, and periodicity of the metallic nanostructures. Nevertheless, the aforementioned parameters allow a limited modulation of both SPP and LSPR over a narrow window of frequencies. To overcome this constraint, we have proposed and realized the alloying of metals via physical deposition methods as a paradigm to almost arbitrarily tuning their optical behavior in the UV-NIR, which leads to permittivity values currently not available. Our approach offers an additional knob, chemical composition, to engineer light-matter interactions in metallic materials. This Account highlights recent progress in using alloying as a pathway to control the optical behavior of metallic thin films and nanostructures for energy harvesting and storage applications, including (photo)catalysis, photovoltaics, superabsorbers, hydrogen storage, among other systems. We choose to primarily focus on the optical properties of the metallic mixtures and in their near- to far-field responses in the UV-NIR range of the spectrum as they represent key parameters for materials' selection for the devices above. By alloying, it is possible to obtain metallic materials with LSPR not available for pure metals, which can enable the further control of the electromagnetic spectrum. First, we discuss how the permittivity of binary mixtures of coinage metals (Au, Ag, and Cu) can be tailored based on the chemical composition of their pure counterparts. Second, we present how novel metallic materials can be designed through band structure engineering through density functional theory (DFT), a paradigm that could benefit from artificial intelligence methods. Concerning alloyed thin films, we discuss the promise of earth-abundant metals and provide an example of the superior performance of AlCu in superabsorbers. In the realm of nanostructures, we focus the discussion on physical deposition methods, where we provide a detailed analysis of how chemical composition can affect the far- and near-field responses of metallic building blocks. Finally, we provide a brief outlook of promising next steps in the field.

Structure-Property-Performance Relationship of Ultrathin Pd-Au Alloy Catalyst Layers for Low-Temperature Ethanol Oxidation in Alkaline Media.

Pd-containing alloys are promising materials for catalysis. Yet, the relationship of the structure-property performance strongly depends on their chemical composition, which is currently not fully resolved. Herein, we present a physical vapor deposition methodology for developing PdxAu1-x alloys with fine control over the chemical composition. We establish direct correlations between the composition and these materials' structural and electronic properties with its catalytic activity in an ethanol (EtOH) oxidation reaction. By combining X-ray diffraction (XRD) and X-ray photelectron spectroscopy (XPS) measurements, we validate that the Pd content within both bulk and surface compositions can be finely controlled in an ultrathin-film regime. Catalytic oxidation of EtOH on the PdxAu1-x electrodes presents the largest forward-sweeping current density for x = 0.73 at ∼135 mA cm-2, with the lowest onset potential and largest peak activity of 639 A gPd-1 observed for x = 0.58. Density functional theory (DFT) calculations and XPS measurements demonstrate that the valence band of the alloys is completely dominated by Pd particularly near the Fermi level, regardless of its chemical composition. Moreover, DFT provides key insights into the PdxAu1-x ligand effect, with relevant chemisorption activity descriptors probed for a large number of surface arrangements. These results demonstrate that alloys can outperform pure metals in catalytic processes, with fine control of the chemical composition being a powerful tuning knob for the electronic properties and, therefore, the catalytic activity of ultrathin PdxAu1-x catalysts. Our high-throughput experimental methodology, in connection with DFT calculations, provides a unique foundation for further materials' discovery, including machine-learning predictions for novel alloys, the development of Pd-alloyed membranes for the purification of reformate gases, binder-free ultrathin electrocatalysts for fuel cells, and room temperature lithography-based development of nanostructures for optically driven processes.

Cesium-Incorporated Triple Cation Perovskites Deliver Fully Reversible and Stable Nanoscale Voltage Response.

Perovskite solar cells that incorporate small concentrations of Cs in their A-site have shown increased lifetime and improved device performance. Yet, the development of fully stable devices operating near the theoretical limit requires understanding how Cs influences perovskites' electrical properties at the nanoscale. Here, we determine how the chemical composition of three perovskites (MAPbBr3, MAPbI3, and Cs-mixed) affects their short- and long-term voltage stabilities, with <50 nm spatial resolution. We map an anomalous irreversible electrical signature on MAPbBr3 at the mesoscale, resulting in local V oc variations of ∼400 mV, and in entire grains with negative contribution to the V oc. These measurements prove the necessity of high spatial resolution mapping to elucidate the fundamental limitations of this emerging material. Conversely, we capture the fully reversible voltage response of Cs-mixed perovskites, composed by Cs0.06(MA0.17FA0.83)0.94Pb(I0.83Br0.17)3, demonstrating that the desired electrical output persists even at the nanoscale. The Cs-mixed material presents no spatial variation in V oc, as ion motion is restricted. Our results show that the nanoscale electrical behavior of the perovskites is intimately connected to their chemical composition and macroscopic response.

Multiscale Functional Imaging of Interfaces through Atomic Force Microscopy Using Harmonic Mixing.

The spatial resolution of atomic force microscopy (AFM) needed to resolve material interfaces is limited by the tip-sample separation ( d) dependence of the force used to record an image. Here, we present a new multiscale functional imaging technique that allows for in situ tunable spatial resolution, which can be applied to a wide range of inhomogeneous materials, devices, and interfaces. Our approach uses a multifrequency method to generate a signal whose d-dependence is controlled by mixing harmonics of the cantilever's oscillation with a modulated force. The spatial resolution of the resulting image is determined by the signal's d-dependence. Our measurements using harmonic mixing (HM) show that we can change the d-dependence of a force signal to improve spatial resolution by up to a factor of two compared to conventional methods. We demonstrate the technique with both Kelvin probe force microscopy (KPFM) and bimodal AFM to show its generality. Bimodal AFM with harmonic mixing actuation separates conservative from dissipative forces and is used to identify the regions of adhesive residue on exfoliated graphene. Our electrostatic measurements with open-loop KPFM demonstrate that multiple force modulations may be applied at once. Further, this method can be applied to any tip-sample force that can be modulated, for example, electrostatic, magnetic, and photoinduced forces, showing its universality. Because HM enables in situ switching between high sensitivity and high spatial resolution with any periodic driving force, we foresee this technique as a critical advancement for multiscale functional imaging.

Humidity-Induced Photoluminescence Hysteresis in Variable Cs/Br Ratio Hybrid Perovskites.

Hybrid organic-inorganic perovskites containing Cs are a promising new material for light-absorbing and light-emitting optoelectronics. However, the impact of environmental conditions on their optical properties is not fully understood. Here, we elucidate and quantify the influence of distinct humidity levels on the charge carrier recombination in Cs xFA1- xPb(I yBr1- y)3 perovskites. Using in situ environmental photoluminescence (PL), we temporally and spectrally resolve light emission within a loop of critical relative humidity (rH) levels. Our measurements show that exposure up to 35% rH increases the PL emission for all Cs (10-17%) and Br (17-38%) concentrations investigated here. Spectrally, samples with larger Br concentrations exhibit PL redshift at higher humidity levels, revealing water-driven halide segregation. The compositions considered present hysteresis in their PL intensity upon returning to a low-moisture environment due to partially reversible hydration of the perovskites. Our findings demonstrate that the Cs/Br ratio strongly influences both the spectral stability and extent of light emission hysteresis. We expect our method to become standard when testing the stability of emerging perovskites, including lead-free options, and to be combined with other parameters known for affecting material degradation, e.g., oxygen and temperature.

From Microparticles to Nanowires and Back: Radical Transformations in Plated Li Metal Morphology Revealed via in Situ Scanning Electron Microscopy.

Li metal is the preferred anode material for all-solid-state Li batteries. However, a stable plating and stripping of Li metal at the anode-solid electrolyte interface remains a significant challenge particularly at practically feasible current densities. This problem usually relates to high and/or inhomogeneous Li-electrode-electrolyte interfacial impedance and formation and growth of high-aspect-ratio dendritic Li deposits at the electrode-electrolyte interface, which eventually shunt the battery. To better understand details of Li metal plating, we use operando electron microscopy and Auger spectroscopy to probe nucleation, growth, and stripping of Li metal during cycling of a model solid-state Li battery as a function of current density and oxygen pressure. We find a linear correlation between the nucleation density of Li clusters and the charging rate in an ultrahigh vacuum, which agrees with a classical nucleation and growth model. Moreover, the trace amount of oxidizing gas (≈10-6 Pa of O2) promotes the Li growth in a form of nanowires due to a fine balance between the ion current density and a growth rate of a thin lithium-oxide shell on the surface of the metallic Li. Interestingly, increasing the partial pressure of O2 to 10-5 Pa resumes Li plating in a form of 3D particles. Our results demonstrate the importance of trace amounts of preexisting or ambient oxidizing species on lithiation processes in solid-state batteries.

Imaging and Analysis of Encapsulated Objects through Self-Assembled Electron and Optically Transparent Graphene Oxide Membranes.

We demonstrate a technique for facile encapsulation and adhesion of micro- and nano objects on arbitrary substrates, stencils, and micro structured surfaces by ultrathin graphene oxide membranes via a simple drop casting of graphene oxide solution. A self-assembled encapsulating membrane forms during the drying process at the liquid-air and liquid-solid interfaces and consists of a water-permeable quasi-2D network of overlapping graphene oxide flakes. Upon drying and interlocking between the flakes, the encapsulating coating around the object becomes mechanically robust, chemically protective, and yet highly transparent to electrons and photons in a wide energy range, enabling microscopic and spectroscopic access to encapsulated objects. The characteristic encapsulation scenarios were demonstrated on a set of representative inorganic and organic micro and nano-objects and microstructured surfaces. Different coating regimes can be achieved by controlling the pH of the supporting solution, and the hydrophobicity and morphology of interfaces. Several specific phenomena such as compression of encased objects by contracting membranes as well as hierarchical encapsulations were observed. Finally, electron as well as optical microscopy and analysis of encapsulated objects along with the membrane effect on the image contrast formation, and signal attenuation are discussed.

Real-Time Nanoscale Open-Circuit Voltage Dynamics of Perovskite Solar Cells.

Hybrid organic-inorganic perovskites based on methylammonium lead (MAPbI3) are an emerging material with great potential for high-performance and low-cost photovoltaics. However, for perovskites to become a competitive and reliable solar cell technology their instability and spatial variation must be understood and controlled. While the macroscopic characterization of the devices as a function of time is very informative, a nanoscale identification of their real-time local optoelectronic response is still missing. Here, we implement a four-dimensional imaging method through illuminated heterodyne Kelvin probe force microscopy to spatially (<50 nm) and temporally (16 s/scan) resolve the voltage of perovskite solar cells in a low relative humidity environment. Local open-circuit voltage (Voc) images show nanoscale sites with voltage variation >300 mV under 1-sun illumination. Surprisingly, regions of voltage that relax in seconds and after several minutes consistently coexist. Time-dependent changes of the local Voc are likely due to intragrain ion migration and are reversible at low injection level. These results show for the first time the real-time transient behavior of the Voc in perovskite solar cells at the nanoscale. Understanding and controlling the light-induced electrical changes that affect device performance are critical to the further development of stable perovskite-based solar technologies.

Toward Clean Suspended CVD Graphene.

The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the target of interest. Here, we use thermally evaporated anthracene films as the sacrificial layer for graphene transfer onto an arbitrary substrate. We show that clean suspended graphene can be achieved via desorbing the anthracene layer at temperatures in the 100 °C to 150 °C range, followed by two sequential annealing steps for the final cleaning, using Pt catalyst and activated carbon. The cleanliness of the suspended graphene membranes was analyzed employing the high surface sensitivity of low energy scanning electron microscopy and x-ray photoelectron spectroscopy. A quantitative comparison with two other commonly used transfer methods revealed the superiority of the anthracene approach to obtain larger area of clean, suspended CVD graphene. Our graphene transfer method based on anthracene paves the way for integrating cleaner graphene in various types of complex devices, including the ones that are heat and humidity sensitive.