Lateral Phase Research Articles

Lateral Phase Heterojunction for Perovskite Microoptoelectronics.

Perovskite heterojunction engineering is the prerequisite but still a deficiency in the fabrication of micro-optoelectronic devices, where the present top-down or bottom-up techniques mainly focus on preparing the vertical heterojunction stacks. Perovskite lateral heterojunction structures generally rely on epitaxial growth, which cannot meet the demands of mass production of micro-devices. Here, a contact diffusion lithography technique is proposed to demonstrate a perovskite lateral phase heterojunction (LPH) polycrystalline film by ion-driven local phase transition. Under the guidance of thermodynamic simulations, methylamine contact and migration collectively promote in situ formation of α-phase formamidine-based perovskite patterns surrounded by δ-phase polymorphs. Spontaneous type-I heterojunction alignment between α- and δ-phases establishes energy funnels in the LPH film to facilitate carrier utilization and radiative recombination. The wide-bandgap δ-phase also serves as the coplanar isolator to achieve local anti-leakage for device integration. Based on the bright and stable LPH pattern layer, the near-infrared microscale perovskite light-emitting diode (micro-PeLED) with impressive device performance is achieved by following conventional device fabrication protocol. The proposed LPH enriches the perovskite heterojunction family, creates a new optoelectronic processing platform, and advances its versatile applications in micro-optoelectronics and photonics.

The reference window for reduced perturbation of the reference wave in electrical biasing off-axis electron holography

The perturbation of the reference wave due to electric stray fields represents a major challenge in quantitative electron holographic investigations. By introducing a focused-ion-beam-milled rectangular hole, the reference window, in an area of nearly constant electrostatic potential of the sample, this perturbation can be significantly reduced. The edge of the window forms a closed conducting loop, acting similarly to a Faraday cage, shielding the influence of the stray field on the reference wave to some extent. In this work, the shielding effect of the reference window is systematically investigated by comparing electron holograms of an electrically biased coplanar capacitor, as a well-known reference sample, with finite element simulations. It is shown that the introduction of the reference window into electrical biasing samples both suppresses unknown lateral phase distortions substantially and in addition improves the agreement of the experimentally observed phase slope with that expected by simulation significantly, particularly for small object-reference wave distances. Consequently, a slight adjustment of the sample geometry results in an improved reproducibility of electron holographic electrical biasing experiments, which is a significant step towards quantitative evaluation.

Effect of phosphatidylcholine regioisomerism on lateral segregation of milk sphingomyelin in bilayer membranes

Milk fat globule membrane (MFGM) promotes the lateral phase separation of milk lipids and stabilizes the fat globules in milk. The composition and structures of lipids have a significant impact on physicochemical properties of MFGM, which in turn influences the digestion and absorption of milk lipids. Phospholipids (PL), sphingolipids, and cholesterol are the major lipid constituents of MFGM. While the effects of the head-group and structure of the fatty acids (FAs) on membrane properties are commonly studied, little is known on the impact of PL regioisomerism. The present study investigated the impact of phosphatidylcholine (PC) regioisomerism on lateral segregation of milk-sphingomyelin (milk-SM) as well as the influence on the interaction of milk-SM with ceramide and cholesterol in simulated membrane systems. The regioisomer pairs of four molecular species PC 16:0/18:1n-9, PC 16:0/18:2n-6, PC 16:0/18:3n-3, and PC 16:0/20:4n-6 were included in this study. The lateral segregation was determined using lifetime analysis of trans-parinaric acid (tPA) fluorescence. Thermostability of the domains was detected using steady-state anisotropy of tPA. Our results demonstrated a clear impact of PC regioisomerism on membrane properties. PC regioisomers having the unsaturated FAs at the sn-2 position enhanced the lateral segregation of milk-SM with and without the presence of ceramide and cholesterol compared to the regioiosmers having 16:0 at the sn-2 position. Furthermore, the characteristics i. e. the acyl chain length and degree of unsaturatin of sn-2 FA of the PCs had a major impact on the milk-SM gel phase and the intermolecular forces between milk-SM and ceramide/cholesterol. This work is the first investigation showing the effect of PL regioisomerism on milk-SM domains, which might have significant influence on functional properties of MFGM.

Interphase-Controlled Inkjet Printing of MicroInlaid OLEDs: Effects of Solvent- and Solute-Polymer Interactions.

Inkjet printing, a highly promising technique for the cost-effective fabrication of large-scale organic light-emitting devices (OLEDs), typically necessitates the intricate alignment of precisely patterned insulating layers. Recently, we introduced a unique single-step inkjet printing process that produces well-patterned microinlaid spots of functional compounds through insulating polymer layers. This approach exploits lateral phase separation between the solute of functional compounds and the polymer, allowing the simultaneous spatial etching of the polymer and the infilling of the solute using a single inkjet-printed sessile droplet. Here, we demonstrate that the interaction between the solvent and polymer, as well as the solute and polymer, critically determines the precision and efficiency of printing. This is particularly evident when using either the insulating poly(vinylpyridine) isomer of poly(4-vinylpyridine) (P4VP) or poly(2-vinylpyridine) (P2VP) with chloroform as a solvent, which allows for a detailed examination of these interactions based on certain solubility parameters. Micro-Raman spectroscopy reveals that the self-organizing capability of the microinlaid spots with P4VP is superior to that with P2VP. This is due to the fact that P2VP shows higher affinity to the solvent and causes imperfect phase separation as compared to P4VP. As a result, a performance evaluation demonstrates enhanced device performance for inkjet-printed green micro-OLEDs with P4VP, exhibiting a higher external quantum efficiency of 3.3% compared to that of 2.3% achieved with P2VP. These findings elucidate the important roles of solvent-polymer and solute-polymer interactions in the inkjet printing process, leading to interfacial control of inkjet printing technique for the cost-effective production of high-performance and high-resolution micro-OLEDs.

Architecture and dynamics of Precambrian linear megadunes: Galho do Miguel Formation, Mesoproterozoic, South-East Brazil

Recognizing the deposits of linear megadunes in ancient aeolian successions is challenging when the original bedform topography is not preserved. The present study provides a detailed analysis of the depositional architecture of an ∼ 80 m-thick interval of the Mesoproterozoic Galho do Miguel Formation (SE Brazil) to reconstruct the original morphologies of linear megadunes and to understand their dynamics. The depositional architecture reveals compound cross-bedded sets, which transition laterally into thick low-angle cross-stratified sets and planar-parallel sandstone beds. The depositional features indicate the presence of complex megadunes separated by adjoining wide dry inter-megadune areas, which were themselves flooded seasonally by a water table that rose above the depositional surface. Linear megadunes experienced two phases of development: vertical accretion and subsequent episode of lateral migration. During the vertical accretion phase, high sediment supply, typical of Precambrian aeolian systems, and the convergence of winds from two distinct directions promoted high rates of megadune growth, bedform elongation, and the formation of superimposed dunes. The lateral migration phase was characterised by a component of lateral bedform shift relative to the main along-crest sediment transport direction; this prevented preservation of a bimodal pattern of dune cross-strata azimuths. The accumulation of these deposits occurred via a combination of megadune climbing that occurred with progressive rise of the water-table level. The water-table rise hindered cannibalization of the lower parts of the migrating megadunes, allowing the accumulation and subsequent preservation of megadune sandstone packages. The rise of the water table was also responsible for the accumulation of thick dry inter-megadune strata. The unusual thickness of linear megadune and inter-megadune deposits of the Galho do Miguel Formation, as compared with Phanerozoic examples, are attributed to the interplay between the barren conditions of the early Earth, the morphodynamics of the linear megadunes, and the seasonal impact of the water table at the accumulation surface. Without a water-table control, opportunities for megadune accumulation and preservation were likely limited in Precambrian ergs.

High-speed lateral scanning white-light phase shift interferometry.

In this study, we present lateral scanning white light interferometry (LS-WLI), where phase-shifting algorithms are applied to inspect the topography of a large field of view (FOV) with high-speed measurements. At a point, the interference signal must be acquired with a specific condition to adapt the phase-shifting algorithm. This means that all points have two points, of which the phase difference is π/2, when the number of points acquired in a phase period is multiple of 4, despite increasing the data points in a period. Consequently, stretching the fringe spacing in LS-WLI facilitates the application of phase-shift techniques, thereby enhancing stage speed, even with a fixed camera speed. Using the proposed method, we can successfully obtain a laterally expended topographic image as 5.25 mm × 1.25 mm, where the step height of the microstructure is 140 nm.

Evaluating the Rheological Controls on Topography Development During Craton Stabilization: Objective Approaches to Comparing Geodynamic Models

AbstractSurface topography is an important yet largely neglected aspect of the early evolution of cratons. The lateral accretion of cratonic nuclei inevitably forms orogenic belts that subsequently provide a sediment source for large, resource‐rich intracratonic basins, but to date, geodynamic models have focused exclusively on lithospheric root processes. Here we use two‐dimensional thermal‐mechanical models to study the topography and lithospheric deformation during 50 Myr of compression of a cratonic nucleus, to simulate the lateral accretion phase of craton growth in the Neoarchean. Although the cratonic nucleus thickens slightly during the compression phase, most of the deformation occurs in the regions adjacent to the nucleus that have weaker lithosphere. Here, crustal thickness triples developing high topography in excess of 10 km without active erosion. Models with different initial rheological parameters will have different final topography and lithosphere geometry, but in general it is difficult to shorten and deform the depleted cratonic nucleus, unless there are significantly weak heterogeneities in the mantle lithosphere. We apply two quantitative analysis techniques to objectively evaluate a multitude of model outputs. Cross‐correlation clustering (CCC) measures the degree of similarity between topography profiles and categorizes models based on the general topographic character. Six different topography families are possible in the context of our models and crustal strength is the most important parameter affecting the shape. From principal component analysis (PCA) we identify four dominant lithosphere geometries. When used together, these two methods provide distinct yet complementary information about the surface and subsurface deformation features in our models.

Distributed Intelligent Vehicle Path Tracking and Stability Cooperative Control

To enhance the path tracking capability and driving stability of intelligent vehicles, a controller is designed that synergizes active front wheel steering (AFS) and direct yaw moment (DYC), specifically tailored for distributed-drive electric vehicles. To address the challenge of determining the weight matrix in the linear quadratic regulator (LQR) algorithm during the path tracking design for intelligent vehicles on conventional roads, a genetic algorithm (GA)-optimized LQR path tracking controller is introduced. The 2-degree-of-freedom vehicle dynamics error model and the desired path information are established. The genetic algorithm optimization strategy, utilizing the vehicle’s lateral error, heading error, and output front wheel steering angle as the objective functions, is employed to optimally determine the weight matrices Q and R. Subsequently, the optimal front wheel steering angle control (AFS) output of the vehicle is calculated. Under extreme operating conditions, to enhance vehicle dynamics stability, while ensuring effective path tracking, the active yaw moment is crafted using the sliding mode control with a hyperbolic tangent convergence law function. The control weights of the sliding mode surface related to the center-of-mass lateral declination are adjusted based on the theory of the center-of-mass lateral declination phase diagram, and the vehicle’s target yaw moment is calculated. Validation is conducted through Matlab/Simulink and Carsim co-simulation. The results demonstrate that the genetic algorithm-optimized LQR path tracking controller enhances vehicle tracking accuracy and exhibits improved robustness under conventional road conditions. In extreme working conditions, the designed path tracking and stability cooperative controller (AFS+DYC) is implemented to enhance the vehicle’s path tracking effect, while ensuring its driving stability.

Tuning phase separation in DPPDTT/PMMA blend to achieve molecular self-assembly in the conducting polymer for organic field effect transistors.

The semiconductor/insulator blends for organic field-effect transistors are a potential solution to improve the charge transport in the active layer by inducing phase separation in the blends. However, the technique is less investigated for long-chain conducting polymers such as Poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b]thiophene)] (DPPDTT), and lateral phase separation is generally reported due to the instability during solvent evaporation, which results in degraded device performance. Herein, we report how to tailor the dominant mechanism of phase separation in such blends and the molecular assembly of the polymer. For DPPDTT/PMMA blends, we found that for higher DPPDTT concentrations (more than 75%) where the vertical phase separation mechanism is dominant, PMMA assisted in the self-assembly of DPPDTT to form nanowires and micro-transport channels on top of PMMA. The formation of nanowires yielded 13 times higher mobility as compared to pristine devices. For blend ratios with DPPDTT ≤ 50%, both the competing mechanisms, vertical and lateral phase separation, are taking place. It resulted in somewhat lower charge carrier mobilities. Hence, our results show that by systematic tuning of the blend ratio, PMMA can act as an excellent binding material in long-chain polymers such as DPPDTT and produce vertically stratified and aligned structures to ensure high mobility devices.

A Fusion Network with Stacked Denoise Autoencoder and Meta Learning for Lateral Walking Gait Phase Recognition and Multi-Step-Ahead Prediction.

Lateral walking gait phase recognition and prediction are the premise of hip exoskeleton application in lateral resistance walk exercise. In this work, we presented a fusion network with stacked denoise autoencoder and meta learning (SDA-NN-ML) to recognize gait phase and predict gait percentage from IMU signals. Experiments were conducted to detect the four lateral walking gait phases and predict their percentage in 10 healthy subjects across different speeds. The performance of SDA-NN-ML and other widely used algorithms including Support Vector Machine (SVM), Adaptive Boosting (AdaBoost) and Long Short Term Memory (LSTM) were evaluated. The cross-subject recognition accuracy of SDA-NN-ML (89.94%) decreased by 4.62% compared to the training accuracy, which outperformed SVM (8.60%), AdaBoost (5.61%), and LSTM (7.12%). For real-time and cross-subject prediction of gait phase percentage, the RMSE of SDA-NN-ML (0.2043) outperformed that of a single regression network (0.2426). With a signal noise ratio of 100:30, the cross-subject recognition accuracy decreased by a mere 5.70%, while the prediction result (RMSE) of SDA-NN-ML increased by 0.0167 when compared to the noise-free results. SDA-NN-ML demonstrates a stable multi-step-ahead prediction ability with an accuracy higher than 82.50% and an RMSE of less than 0.23 when the ahead time is less than 200 ms. The results demonstrated that the proposed method has high accuracy and robust performance in lateral walking gait recognition and prediction.

Structural characterization of lateral phase separation in polymer-lipid hybrid membranes.

Hierarchic self-assembly is the main mechanism used to create diverse structures using soft materials. This is a case for both synthetic materials and biomolecular systems, as exemplified by the non-covalent organization of lipids into membranes. In nature, lipids often assemble into single bilayers, but other nanostructures are encountered, such as bilayer stacks and tubular and vesicular aggregates. Synthetic block copolymers can be engineered to recapitulate many of the structures, forms, and functions of lipid systems. When block copolymers are amphiphilic, they can be inserted or co-assembled into hybrid membranes that exhibit synergistic structural, permeability, and mechanical properties. One example is the emergence of lateral phase separation akin to the raft formation in biomembranes. When higher-order structures, such as hybrid membranes, are formed, this lateral phase separation can be correlated across membranes in the stack. This chapter outlines a set of important methods, such as X-ray Scattering, Atomic Force Microscopy, and Cryo-Electron Microscopy, that are relevant to characterizing and evaluating lateral and correlated phase separation in hybrid membranes at the nano and mesoscales. Understanding the phase behavior of polymer-lipid hybrid materials could lead to innovative advancements in biomimetic membrane separation systems.

Lipid membranes supported by polydimethylsiloxane substrates with designed geometry.

The membrane curvature of cells and intracellular compartments continuously adapts to enable cells to perform vital functions, from cell division to signal trafficking. Understanding how membrane geometry affects these processes in vivo is challenging because of the biochemical and geometrical complexity as well as the short time and small length scales involved in cellular processes. By contrast, in vitro model membranes with engineered curvature would provide a versatile platform for this investigation and applications to biosensing and biocomputing. Here, we present a strategy that allows fabrication of lipid membranes with designed shape by combining 3D micro-printing and replica-molding lithography with polydimethylsiloxane to create curved micrometer-sized scaffolds with virtually any geometry. The resulting supported lipid membranes are homogeneous and fluid. We demonstrate the versatility of the system by fabricating structures of interesting combinations of mean and Gaussian curvature. We study the lateral phase separation and how local curvature influences the effective diffusion coefficient. Overall, we offer a bio-compatible platform for understanding curvature-dependent cellular processes and developing programmable bio-interfaces for living cells and nanostructures.

Past, Present, and Future Anatomy of an Oil Brine Plume Remediation near Poplar, Montana: A Case Study

AbstractThe Biere #1‐22 oil production well near Poplar, Montana leaked brine and light nonaqueous phase liquid (LNAPL) to the shallow alluvial aquifer for several years before final closure in 2002. Since 2008, 2.5 billion L of brine have been removed (~90% of the original Cl mass). However, Cl will not reach the original background levels due to the reservoir of solutes entrained in the Bearpaw bedrock remnant from the lateral dense aqueous phase liquid flow across the alluvial/bedrock interface. After removal of ~100,000 L of product since 2006, residual LNAPL is now confined to 2.2 ha (5.5 acres) a decrease from the original 2.7 ha (6.6 acres) areal extent by 17%. The initial ~7.5 m thick product in 2002 is stable at a maximum of ~1 m. However, LNAPL has infiltrated into fine‐grained clay/silt units forming a smear zone in lenses 10 to 20 m bgs. Ongoing remediation has successfully mitigated benzene groundwater impacts over the last 14 years, with the benzene plume area having decreased by >99% (at the 5 μg/L) level from the maximum ~140 ha in 2002. This appears to be the first study evaluating the challenges to remediate a mixed LNAPL/dissolved organic/inorganic plume. Based on the mass removal to date, the asymptotic trends in solute concentrations, unpotable background groundwater quality, absence of a source/receptor pathway, lack of beneficial groundwater use, duration of mitigation with no obvious future accrual in benefit and the availability of institutional controls, it seems that the remedial strategies employed since 2006 have met their cost/benefit goals.

Enhanced Terahertz Phonon Polariton in Lithium Niobate Chip

AbstractTerahertz (THz) phonon polaritons, fundamental quasi‐particles that couple lattice vibrations with electromagnetic fields at THz frequencies, are found in a variety of materials that offer the potential for a wide range of THz optoelectronic devices and on‐chip integrated systems. However, these compact devices and on‐chip systems are hampered by the absence of on‐chip powerful THz phonon polariton sources. In this study, the efficient generation and amplification of THz phonon polaritons are proposed and directly visualized on a lithium niobate (LN) chip via a tilted pulsefront phase matching technique. By combining lateral pumping and phase matching schemes, two orders of magnitude are successfully attained in the interaction distance between the pump light and the LN chip, accompanied by a substantial amplification of generated THz phonon polariton. The results of this study may lead to abundant potential applications in chip scale THz photonic devices and systems based on LN materials and its integrated heterostructures.

Experimentally determined leaflet-leaflet phase diagram of an asymmetric lipid bilayer.

We have determined the partial leaflet-leaflet phase diagram of an asymmetric lipid bilayer at ambient temperature using asymmetric giant unilamellar vesicles (aGUVs). Symmetric GUVs with varying amounts of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) were hemifused to a supported lipid bilayer (SLB) composed of DOPC, resulting in lipid exchange between their outer leaflets. The GUVs and SLB contained a red and green lipid fluorophore, respectively, thus enabling the use of confocal fluorescence imaging to determine both the extent of lipid exchange (quantified for individual vesicles by the loss of red intensity and gain of green intensity) and the presence or absence of phase separation in aGUVs. Consistent with previous reports, we found that hemifusion results in large variation in outer leaflet exchange for individual GUVs, which allowed us to interrogate the phase behavior at multiple points within the asymmetric composition space of the binary mixture. When initially symmetric GUVs showed coexisting gel and fluid domains, aGUVs with less than ~50% outer leaflet exchange were also phase-separated. In contrast, aGUVs with greater than 50% outer leaflet exchange were uniform and fluid. In some cases, we also observed three coexisting bilayer-spanning phases: two registered phases and an anti-registered phase. These results suggest that a relatively large unfavorable midplane interaction between ordered and disordered phases in opposing leaflets (i.e., a midplane surface tension) can overwhelm the driving force for lateral phase separation within one of the leaflets, resulting in an asymmetric bilayer with two uniformly mixed leaflets that is poised to phase-separate upon leaflet scrambling.

Multimode experimental band dynamics of resonant nanophotonic lattices.

Subwavelength resonant lattices provide a host of interesting spectral expressions on broadside illumination. The resonance mechanism is based on generation of lateral Bloch modes phase matched to evanescent diffraction orders. The leaky mode structure and mode count determine the spectra and the number of resonance states. Here, we study band flips and bound-state transitions in guided-mode resonant structures supporting multiple resonant modes. We present theoretical simulations and experimental results for a subwavelength silicon-nitride lattice integrated with a liquid film with adjustable boundary. The relatively thick liquid waveguiding region supports additional modes such that the first four transverse-electric (TE) leaky modes are present and generate observable resonance signatures. By varying the duty cycle of the basic lattice in experiment, the 4 bands undergo band transitions and band closures as quantified herein. The experimental results taken in the 1400-1600 nm spectral region agree reasonably well with numerical analysis.

Evaluating pesticide ecotoxicity using a stimuli-response model in liposomes

Pesticides are widely used around the home and in agriculture to control unwanted populations; however, they may also be toxic to non-targeted organisms. Because traditional methods of assessing pesticide toxicity are expensive, lengthy, and ethically questionable, we evaluated pesticide toxicities using stimuli-responses in liposomes. Pesticide ecotoxicity was evaluated using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes. Changes in membrane permeability were measured using calcein leakage assays as stimuli-responses in the presence of six pesticides (Chlorpyrifos-methyl, fluometuron, imidacloprid, pirimicarb, pyrethrin, and quizalofop-ethyl), for which the calcein release rate was analyzed using a first-order kinetics equation. The calcein release rate constants of the DPPC liposomes were used to classify the pesticides into lower and higher toxicity groups. In each group, the initial calcein release rate from the DPPC/DOPC liposomes mixed with 33 ​mol% DOPC correlated well with previously reported pesticide toxicities. The DOPC liposomes underwent lateral phase separation in a different manner between the two toxicity groups. Pesticides with lower toxicities were partitioned in the DPPC-enriched phase, disrupting the gel phase order through their hydrophobicity, whereas pesticides with higher toxicity were partitioned in the DOPC-enriched phase and stabilizing the liquid disordered phase owing to their hydrophobicity and molecular shape. The toxicity of each pesticide was well represented by an equation that combined the calcein release rate constant of the DPPC liposomes and the initial calcein release rate of the 33 ​mol% DOPC mixed liposomes. The findings indicate that stimuli-response assays using liposomes can be used to complement traditional ecotoxicity assessments.

Generation of Bloch surface beams with arbitrarily designed phases.

We proposed a new manipulation method for Bloch surface waves that can almost arbitrarily modulate the lateral phase through in-plane wave-vector matching. The Bloch surface beam is generated by a laser beam from a glass substrate incident on a carefully designed nanoarray structure, which can provide the missing momentum between the two beams and set the required initial phase of the Bloch surface beam. An internal mode was used as a channel between the incident and surface beams to improve the excitation efficiency. Using this method, we successfully realized and demonstrated the properties of various Bloch surface beams, including subwavelength-focused, self-accelerating Airy, and diffraction-free collimated beams. This manipulation method, along with the generated Bloch surface beams, will facilitate the development of two-dimensional optical systems and benefit potential applications of lab-on-chip photonic integrations.

Two-dimensional lateral anatase-rutile TiO2 phase junctions with oxygen vacancies for robust photoelectrochemical water splitting

Exploiting the photoelectrode materials with broad solar light response, high-efficient separation of photogenerated charges and abundant active sites is extremely vital yet enormously challenging. Herein, an innovative two-dimensional (2D) lateral anatase-rutile TiO2 phase junctions with controllable oxygen vacancies perpendicularly aligned on Ti mesh is presented. Our experimental observations and theoretical calculations corroborate explicitly that the 2D lateral phase junctions together with three-dimensional arrays not only exhibit the high-efficient photogenerated charges separation guaranteed by the build-in electric field at the side-to-side interface, but also furnish enriching active sites. Moreover, the interfacial oxygen vacancies generate new defect energy levels and serve as electron donors, hence extending visible light response and further accelerating the separation and transfer of photogenerated charges. Profiting from these merits, the optimized photoelectrode yield a pronounced photocurrent density of 1.2 mA/cm2 at 1.23 V vs. RHE with Faradic efficiency of 100%, which is approximately 2.4 times larger than that of pristine 2D TiO2 nanosheets. Furthermore, the incident photon to current conversion efficiency (IPCE) of the optimized photoelectrode is also boosted within both ultraviolet and visible light regions. This research is envisioned deliver the new insight in developing the novel 2D lateral phase junctions for PEC applications.

Imparting High Conductivity to 3D Printed PEDOT:PSS

Complex 3D geometry and high conductivity have generally been mutually exclusive characteristics for conducting polymers. For instance, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), a benchmark conducting polymer, typically exhibits conductivity 1 to 2 orders of magnitude lower in 3D-printed forms compared to 2D-processed thin films, due to its sensitivity to processing conditions. Here, we investigate the main causes of this reduced conductivity, which are found to be (1) the ink formulation strategy and (2) the strong lateral phase separation of the printed filaments. Processing approaches that overcome these factors have produced significant conductivity enhancement to 1200 S/cm, higher than the typical 2D-processed PEDOT:PSS. Our study also unveils a set of guiding principles for optimizing the conductivity of direct ink writing (DIW)-printed PEDOT:PSS, including printing orientation, print bed temperature, and nozzle diameter. With the combination of high conductivity and 3D geometric freedom, potential applications such as omnidirectionally deformable LED devices with strain-independent electrical behavior and bespoke electronics that replicate the shape of human body parts have been demonstrated.