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We report on the nanostructures of organic small-moleculepentacenecrystals that have been vapor-deposited onto the capillary wave surfacesof thin liquid films. The characteristic lateral length of the capillarywave surface or the capillary length can be controlled by changingthe thickness of the liquid films and, thus, the van der Waals interactionwith the substrate. We find that the morphology of the organic crystalsgradually varies from fractals to compact islands as the liquid filmthickness increases. The square of average distance between organiccrystal grains was also found to be proportional to the liquid filmthickness. We discuss the possibility that these effects are drivenby capillary fluctuations at the air–liquid interface. [ABSTRACT FROM AUTHOR]

Multi-component (ternary, quaternary, and beyond) bulk heterojunction (BHJ) active layers are considered one of the most effective ways of increasing the performance of organic photovoltaics (OPVs). Herein, an alternative sequential deposition method for the development of efficient multi-component OPVs without the need for the complex optimization steps typical for blend parameters is discussed. Simple sequential spin-coating of two binary donor:acceptor blends was applied to produce modified quaternary BHJ layers, making full use of the optoelectronic advantages offered by the two binary blends and their optimized morphological features. A combination of theoretical and experimental analyses revealed the occurrence of molecular reorganization during sequential deposition which facilitated self-optimized molecular stratification and cascade energy level alignment. By using expanded universality test to account for the diverse BHJ systems, this sequential deposition methodology creates new opportunities as an alternative fabrication platform to secure high-performance multi-component BHJ OPVs for versatile (i.e., indoor and outdoor) irradiation environments while overcoming many of the drawbacks of conventional manufacturing procedures. Image 1 • Alternative manufacturing process of organic photovoltaics (OPVs) is demonstrated. • Sequential spin-coating of two binary blends produces modified multi-component bulk heterojunction layers. • Performance is optimized for both indoor and outdoor light conditions without the need for fine-tuned blend optimization. • Sequential deposition is a universal platform to achieve optimization-free, high-performance multi-component OPVs. [ABSTRACT FROM AUTHOR]

Inevitable frictional heat, generated by friction, degrades output performance of polymer-based triboelectric nanogenerators (TENGs). To address this issue, we propose to take advantage of using shape memory effect of polyurethane (PU) as a triboelectric layer to not only operate TENG sustainably, but also realize self-boosting power generation performance of TENG by frictional heat. We found that frictional heat sufficiently leads to the glass transition of PU and this transformed PU at elevated temperature contributes to change key parameters, serving to improve performance of TENG, including dielectric constant, work function, and charge trap density. In this work we verified PU harness heat generated by friction and demonstrated 300% increase of the power-generating performance of PU-based TENG with experiencing the glass transition. In addition, we experimentally observed no further temperature elevation around 60 °C in TENG with a continuous rotating friction mode, which offers PU potential to be a promising triboelectric material for high performance TENGs. We demonstrate the self-boosted output performance of triboelectric nanogenerator (TENG) with polyurethane (PU) as a triboelectric polymer. Output perfomance of PU-based TENG can be significantly enhanced by the friction-heat-induced property change of PU such as dielectric constant, work function, and trap site density. In addition, we experimentally observed the output performance PU-based TENG is stable due to self-limited temperature increase up to 60 °C by glass transition in the continuous friction process. Image 1 • We introduce an intriguing approach to overcome a power degradation of triboelectric nanogenerators (TENGs) induced by a temperature rise due to friction heat. • Our findings show that polyurethane (PU) undergoes a glass transition at 55 °C, which gives rise to improve thereof dielectric constant, work function, and trap site density. • We confirmed that the output performance of PU-based TENG was improved by 300% during operating TENG without any help of additional device and temperature of PU-based TENG is self-stabilized around 60 °C after temperature increase up to around 80 °C in the free-standing rotation mode with the continuous friction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Slow crystallization for high oriented perovskite crystals in ambient air. • 18.56% of MAPbI 3 PV has been achieved under the optimal air-process condition. • Optimal device retained over 90% of initial performance after 914 h in dry air. Although the efficiency of inorganic-organic perovskite solar cells (PSCs) has increased significantly owing to intermediate phase induced slow crystallization using dimethyl sulfoxide (DMSO) as a co-solvent in N 2 -filled glovebox, PSCs are generally fabricated in ambient air via a fast crystallization process to protect the perovskite layer from H 2 O or O 2. In this study, we suggest a possibility of slow crystallization process for MAPbI 3 perovskite crystals via intermediate phase formation by adjusting the humidity of air at RH 20%–30%. We obtained high-quality perovskite grains by implementing the slow crystallization process using an antisolvent and the ratio of PbI 2 :MAI:DMSO in the precursor solution at RH 20%–30%. The amount and state of the intermediate phase inside the as-deposited film were analyzed by grazing incidence wide-angle X-ray scattering (GIWAXS) measurements. The deposited perovskite layer with the pure intermediate via extremely slow crystallization showed higher absorption, fewer grain boundaries, and suppressed defect recombination losses than the fast crystallized perovskite phase. Thus, we obtained higher stability and high power conversion efficiency of up to 18.56% in a p-i-n-structured MAPbI 3 -based perovskite solar cell under ambient air with RH 20%–30%. [ABSTRACT FROM AUTHOR]

Ternary blend approaches are demonstrated as a universal means to improve overall performance of organic photovoltaics (OPVs) in both indoor and outdoor conditions. A comparative study on two donors:one acceptor (2D:1A) and one donor:two acceptors (1D:2A) ternary blends shows that both approaches are universally effective for indoor and outdoor operation; the 1D:2A devices incorporating a nonfullerene acceptor (NFA) benefit from less charge recombination and higher power conversion efficiencies (PCEs) for various irradiation conditions, while the performance of the 2D:1A blends depends on the emission spectrum of the incident light source. The synergistic merits of NFAs and ternary structure in the 1D:2A ternary OPVs secure better performance and generality regardless of the incident lighting. A combination of experimental and theoretical analyses unveils that NFAs optimize packing and arrangement of molecules to build efficient cascade ternary junctions in the 1D:2A blends, which can be important design guidelines for the third component in ternary OPVs. The optimized 1D:2A ternary OPV exhibits a new record PCE of 25.6% under a 200 lux light‐emitting diode (LED) and 26.4% under a 1000 lux LED, and superior durability under industrial relevant thermal stress, suggesting new opportunities in diverse practical applications challenging the currently dominant PV technologies. [ABSTRACT FROM AUTHOR]

Here, it is investigated whether an energetic cascade between mixed and pure regions assists in suppressing recombination losses in non‐fullerene acceptor (NFA)‐based organic solar cells. The impact of polymer‐NFA blend composition upon morphology, energetics, charge carrier recombination kinetics, and photocurrent properties are studied. By changing film composition, morphological structures are varied from consisting of highly intermixed polymer‐NFA phases to consisting of both intermixed and pure phase. Cyclic voltammetry is employed to investigate the impact of blend morphology upon NFA lowest unoccupied molecular orbital (LUMO) level energetics. Transient absorption spectroscopy reveals the importance of an energetic cascade between mixed and pure phases in the electron–hole dynamics in order to well separate spatially localized electron–hole pairs. Raman spectroscopy is used to investigate the origin of energetic shift of NFA LUMO levels. It appears that the increase in NFA electron affinity in pure phases relative to mixed phases is correlated with a transition from a relatively planar backbone structure of NFA in pure, aggregated phases, to a more twisted structure in molecularly mixed phases. The studies focus on addressing whether aggregation‐dependent acceptor LUMO level energetics are a general design requirement for both fullerene and NFAs, and quantifying the magnitude, origin, and impact of such energetic shifts upon device performance. [ABSTRACT FROM AUTHOR]

The unique properties of organic photovoltaics (OPVs) offer great promise in emerging applications such as wearable electronics or the Internet of Things. For their successful utilization, OPV operation should be designed for versatile irradiation circumstances in addition to solar light since they should be capable of providing electric power when there is no sunlight or when they operate indoors. Here, a quaternary OPV (Q‐OPV) as a semitransparent, colorful energy platform that operates efficiently under both solar and artificial light irradiation is demonstrated. The experimentally optimized Q‐OPV shows a broadened spectral response and improved charge transport process with suppressed recombination, thereby providing high output powers that are sufficient to autonomously operate low‐power electronic devices. In addition, the Q‐OPV benefits from improved morphological stability with a reduced driving force for grain growth by the increased entropy in the quaternary blend system. The important features of the Q‐OPV platform such as semitransparency, high tolerance to film thickness, and color codability, while pursuing the improved performance and thermal durability, further open new opportunities as an all‐day (24/7/365) power generator in broad practical applications. [ABSTRACT FROM AUTHOR]

Extensive research on bulk‐heterojunction (BHJ) optimization has advanced organic photovoltaics (OPVs). However, the need for research addressing the issue of morphological instability and ensuring long‐term durability remains a priority. Herein, a diffusion‐governed morphological modification methodology via a sequential deposition (SD) process comprising ternary components with low miscibility is demonstrated. Sequential coating of a high glass transition temperature (Tg) material and a host binary blend induces a concentration difference between successively coated layers, allowing for effective blending of immiscible materials during solvent evaporation. The enhanced miscibility of the SD‐processed BHJ layer facilitates molecular interactions between the high Tg material and the host materials, thereby increasing the Tg of the BHJ blend. The SD‐processed OPVs exhibit superior photovoltaic performance and suppressed glass transition under thermal stress compared to reference OPVs fabricated via a conventional method. After 500 h of thermal aging at 85 °C, the SD‐BHJ OPV retains over 80% of its initial efficiency, whereas the reference device shows a drastic drop to below 80% of its initial efficiency after only 80 h. This study provides a step toward efficient, long‐term stable OPVs by overcoming the limitations of blend miscibility and poor thermal durability of conventional BHJ systems via a SD process. [ABSTRACT FROM AUTHOR]

Distribution of Zn 2 + , Al 3 + , and Fe 3 + ions on tetrahedral and octahedral sites in Fe 3 + -doped ZnAl 2 O 4 nanocrystals is studied through detailed x-ray diffraction (XRD) analysis. Significant changes in the intensity ratio of (220), (311), (400), and (422) diffraction peaks upon Fe addition were perceived, whose correlation with lattice inversion, Fe 3 + ions distribution, and ionic vacancies is probed through simulations and Rietveld refinement. Fe 3 + ions were found to be occupying tetrahedral sites in increasing proportion with the doping concentration, leading to decreased spinel inversion. However, different orders of defects, viz., cation and anion vacancies were also found to be playing their part in the statistical distribution of cations on octahedral/tetrahedral interstices. Fe L 2 , 3 -edge x-ray absorption near edge structure spectroscopy indicated Fe 3 + ions being present on tetrahedral as well octahedral interstices and distortion in cation polyhedra, while O K-edge inferred formation of different orders of ionic vacancies upon Fe addition, thereby corroborating the results from XRD. The photoluminescence study illustrated the quenched emission intensity upon Fe doping, with almost no change in emission color, and signatures of tetrahedral/octahedral Fe 3 + occupancy in the lattice. Thus, this study highlights the variation in degrees of freedom associated with atomic arrangements in spinel ZnAl 2 O 4 lattice upon Fe 3 + addition. [ABSTRACT FROM AUTHOR]

We demonstrate that surface stresses in epitaxially grown VO2 nanowires (NWs) have a strong effect on the appearance and stability of intermediate insulating M2 phases, as well as the spatial distribution of insulating and metallic domains during structural phase transitions. During the transition from an insulating M1 phase to a metallic R phase, the coexistence of insulating M1 and M2 phases with the absence of a metallic R phase was observed at atmospheric pressure. In addition, we show that, for a VO2 NW without the presence of an epitaxial interface, surface stresses dominantly lead to spatially inhomogeneous phase transitions between insulating and metallic phases. In contrast, for a VO2 NW with the presence of an epitaxial interface, the strong epitaxial interface interaction leads to additional stresses resulting in uniformly alternating insulating and metallic domains along the NW length. [ABSTRACT FROM AUTHOR]

[Display omitted] • We have fabricated a FePi cocatalyst-coated novel homojunction Fe 2 O 3 photoanode. • Staggered band alignment facilitates bulk charge transfer. • FePi cocatalyst accelerates hole transfer to electrolyte through enhancing surface states. • The optimized photoanode exhibits a photocurrent density of 1.68 mA/cm2 at 1.23 V RHE with 190 mV cathodic onset shifting. • Charge carrier transfer characteristics for PEC water splitting are explored. Hematite (α-Fe 2 O 3) possesses notable benefits in the field of photoelectrochemical (PEC) water splitting. However, the overall low efficiency of the separation and transfer of photogenerated charge carriers significantly hinders its further utilization. Although the occurrence of an internal electric field has the potential to significantly augment the efficiency of charge separation and transfer, there is a crucial need to broaden the scope of its successful application. This study explores a strategy for modifying the coupling between homojunction formation with gradient doping and cocatalyst modification on hematite to boost PEC performance. The developed type II Ti-doped/(Sb-codoped) Fe 2 O 3 :Sb-doped/(Ti-codoped) Fe 2 O 3 (Ti/(Sb)-HT:Sb/(Ti)-HT) homojunction with a staggered band alignment accelerated the bulk charge separation via an intrinsic built-in electric field, while the bulk conductivity was improved using a gradient co-doping approach. Furthermore, the deposition of a FePi cocatalyst expedited the transfer of holes from the photoanode to the electrolyte by increasing the surface states, thereby hastening the water oxidation kinetics. The resulting Ti/(Sb)-HT:Sb/(Ti)-HT@FePi photoanode exhibited a 78.7% increase in photocurrent density compared to the bare Ti-Fe 2 O 3 photoanode (0.94–1.68 mA/cm2 at 1.23 V RHE), accompanied by a charge transfer efficiency of 72.5%. Comprehensive photoelectrochemical investigations revealed that the homojunction and cocatalyst play a vital role in improving the dynamics of both the bulk and surface of the hematite photoanode, thereby facilitating efficient water oxidation. These findings offer a deeper insight into the function of homojunction photoanodes adorned with cocatalysts in the solar water-splitting process. [ABSTRACT FROM AUTHOR]

Here, we report the synergistic effect of dual TiO 2 layers to enhance the PEC performance of Zirconium-doped zinc ferrite (ZZFO) photoanode by improving the charge carrier density and suppressing the photogenerated charge recombination. The TiO 2 underlayer works as a blocking layer to remarkably suppress the back-injection of electrons from the fluorine-doped tin oxide (FTO) leading to reducing the bulk charge recombination. While interlayer TiO 2 improves the bulk charge transfer property of ZZFO photoanodes. The optimal TiO 2 double-layer modified ZZFO photoanode exhibits an enhanced photocurrent of 0.435 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), which is 2.5 times higher than that of the ZZFO photoanode. The effect of each layer was deeply investigated by electrochemical impedance spectroscopy (EIS), intensity-modulated photocurrent spectroscopy (IMPS) and time-resolved photoluminescence studies (TRPL) with the aim of gaining a clear picture of the interface modifications and their impact on the efficiency of the ZZFO photoanode. [Display omitted] • The effect of TiO 2 double-layer on Zr-doped ZnFe 2 O 4 photoanode is investigated. • Ti diffusion/doping effectively suppressed the charge recombination. • TiO 2 underlayer served as a barrier layer for electron back-injection. • TiO 2 interlayer promoted the spinel inversion structure to aid charge separation. • TiO 2 double-layer constructively improved the photoelectrochemical properties. [ABSTRACT FROM AUTHOR]

Orbital anisotropy at interfaces in magnetic heterostructures has been key to pioneering spin–orbit‐related phenomena. However, modulating the interface's electronic structure to make it abnormally asymmetric has been challenging because of lack of appropriate methods. Here, the authors report that low‐energy proton irradiation achieves a strong level of inversion asymmetry and unusual strain at interfaces in [Co/Pd] superlattices through nondestructive, selective removal of oxygen from Co3O4/Pd superlattices during irradiation. Structural investigations corroborate that progressive reduction of Co3O4 into Co establishes pseudomorphic growth with sharp interfaces and atypically large tensile stress. The normal component of orbital to spin magnetic moment at the interface is the largest among those observed in layered Co systems, which is associated with giant orbital anisotropy theoretically confirmed, and resulting very large interfacial magnetic anisotropy is observed. All results attribute not only to giant orbital anisotropy but to enhanced interfacial spin–orbit coupling owing to the pseudomorphic nature at the interface. They are strongly supported by the observation of reversal of polarity of temperature‐dependent Anomalous Hall signal, a signature of Berry phase. This work suggests that establishing both giant orbital anisotropy and strong spin–orbit coupling at the interface is key to exploring spintronic devices with new functionalities. [ABSTRACT FROM AUTHOR]

Increasing multidrug-resistant pathogenic microbial around the world become a global problem, making it imperative to develop effective methods for bacterial inactivation in wastewater. In this study, we propose a multifunctional photoelectrochemical (PEC) system to successfully disinfect microbial cells and degrade orange (II) dyes. CoO x NP were synthesized by spin-coating onto hydrothermally synthesized TiO 2 nanorod arrays followed by electrodeposited NiFe-LDH to develop the NiFe-LDH/CoO x NP-TiO 2 NRs. Interestingly, spin-coated CoO x NP-TiO 2 NRs exhibited a 1.5-fold enhancement in photocurrent (1.384 mA/cm2) than pristine TiO 2 NRs (0.92 mA/cm2). A NiFe-layered double hydroxide (LDH) cocatalysts layer further exhibits the maximum photocurrent density of 1.64 mA/cm2 with IPCE of 84.5% at 1.0 V Ag/AgCl at 380 nm. Furthermore, NiFe-LDH/CoO x -TiO 2 NR photoanodes were effectually employed for photoelectrochemical bacteria disinfection and organic pollutant removals. With NiFe-LDH/CoO x -TiO 2 NR, 99% (120 min) bacterial inactivation and 99% (60 min) orange II dye decomposition efficiency was achieved. Superoxide radicals (−O 2 •), hydroxyl radicals (HO•), and holes (h+) played a critical role in the PEC degradation systems. Due to the synergy between NiFe-LDH cocatalyst and CoO x interlayer, surface water oxidation reactions were accelerated over NiFe-LDH/CoO x NP-TiO 2 NRs. The charge transport process in NiFe-LDH/CoO x NP-TiO 2 NRs photoanode-based PEC system was proposed in detail. Here, NiFe-LDH/CoOx NP-TiO 2 NRs were synthesized by three step approach and achieved 1.64 mA/cm2 further photocurrent density with 99% (120 min) bacterial inactivation and 99% (60 min) orange II dye decomposition efficiency under one sun illumination. [Display omitted] • Surface-tailored NiFe-LDH photoanodes were synthesized by successive spin coating and electrodeposition. • NiFe-LDH photoanodes exhibited 1.78 times photocurrent density (1.64 mA/cm2) than the TiO 2 NR. • Surface-tailored NiFe-LDH achieved 99% (120 min) bacterial inactivation. • The synergy between NiFe-LDH and CoO x led to 99% (60 min) degradation of orange II dye. • The charge transport process in NiFe-LDH/CoO x NP-TiO 2 NRs photoanode is studied in detail. [ABSTRACT FROM AUTHOR]

Ex-situ doping into hematite films is carried out via a short-duration (∼60 s) microwave-assisted metal-ions attachment (MWMA) of tetravalent Zr4+ ion on the surface of FeOOH/FTO, followed by high temperature annealing (HTA) to fabricate Zr4+:Fe 2 O 3 /FTO photoanode for photoelectrochemical (PEC) water splitting. Compared to a simple dipping attachment without microwave irradiation, this MWMA allows a much larger amount of attached Zr4+-ions on the FeOOH precursor, leading to a properly doped photoanode of much higher PEC activity. The primary effect of Zr4+ doping is to improve the charge transport characteristics in the bulk of hematite. In addition, it also boosts charge injection efficiency at the semiconductor and electrolyte interface by forming an inadvertent passivation layer and promoting hole transfer via surface states. As a result, the Zr4+:Fe 2 O 3 /FTO photoanode shows a higher photocurrent density of 1.54 mA cm−2 at 1.23 V RHE under 1 Sun irradiation relative to undoped Fe 2 O 3 /FTO (1.02 mA cm−2) or Zr4+:Fe 2 O 3 /FTO (1.19 mA cm−2) prepared without MWMA. Microwave irradiation energized the suspended Zr4+ ions to give a higher coverage on the FeOOH film for effective doping of hematite photoanode. The Zr-doping improves not only bulk charge transport properties, but also boosts charge injection performance at the semiconductor-electrolyte interface by forming an inadvertent passivation layer and promoting hole transfer via surface states. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The presence of Al electrodes on P3HT:PCBM blended thin films significantly modifies the structure of the films during thermal annealing processes used to produce organic photovoltaic cells. In the absence of an Al electrode, thermal annealing produces very thin (0.7nm) P3HT layers with face-on molecular stacking near the surface of the film and vertically oriented rod-like P3HT crystals in the bulk region with edge-on molecular stacking. Thermal annealing in the presence of an Al electrode makes the preferred orientation of P3HT crystals in the films less prevalent, and Al diffuses into the organic films to form an intermediate layer. The absence of very thin P3HT layers and the less favorable P3HT orientation help to form interpenetrating networks in the organic layer, resulting in better device performance in the films annealed with Al electrodes. [Copyright &y& Elsevier]

Applicability of spinel compounds is mainly governed by cation distribution in them. In the presented study, thermally induced cation ordering is found to influence the emission color of Mg 2 + , Fe 3 + co-doped ZnAl 2 O 4 spinel. Cation distribution is monitored through Mg K-edge, Fe L 2 , 3 -edge, O K-edge X-ray absorption near edge structure spectroscopy and X-ray diffraction analysis using synchrotron radiation. Thermal treatment provided sufficient energy to Zn 2 + , Mg 2 + , Al 3 + and Fe 3 + cations to redistribute themselves on tetrahedral and octahedral sites, and reduce the octahedral distortion, thereby gaining stability. Reduced inversion accompanied by decrease in oxygen vacancies, while increase in tetrahedral and octahedral site vacancies contributed toward more intense blue emission band and quenched yellow band, changing the emission color from bluish-white to blue. Correlation derived between cation ordering and luminescence upon thermal treatment predict Mg 2 + , Fe 3 + co-doped ZnAl 2 O 4 nanophosphors to be useful in thermal sensing applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thin film growth of ferromagnetic van der Waals material Cr 2 Te 3. • Post-growth ex-situ thermal process to control magnetism of the Cr 2 Te 3 thin films. • Annealing-induced change in the Curie temperature and magnetic anisotropy. • Structural analyses reveal c-lattice expansion as origin of the annealing effect. We present a post-growth ex-situ annealing method to control the Curie temperature and magnetic anisotropy of Cr 2 Te 3 van der Waals ferromagnetic thin films. The as-grown Cr 2 Te 3 films exhibit a Curie temperature ∼ 170 K with an out-of-plane magnetic easy axis. Upon high temperature (300 – 400 °C) ex-situ annealing, the magnetic phase of the film changes: the Curie temperature is significantly increased to ∼ 300 K and the magnetic easy axis is reoriented to the in-plane direction. Electronic, chemical, and structural analyses suggest that the c-axis lattice constant expansion, accompanying the annealing process, is the origin of the ex-situ-annealing-induced modulation of the Cr 2 Te 3 film magnetic properties. These results demonstrate that a practical ex-situ annealing process can be effectively used to control the magnetic properties of van der Waals ferromagnetic thin films. Furthermore, the room temperature ferromagnetic ordering emerging upon annealing, along with its robustness against post-growth thermal processes, suggests that the Cr 2 Te 3 thin film is a promising magnetic material candidate for potential application in van-der-Waals-material-based spintronic devices. [ABSTRACT FROM AUTHOR]

Herein the morphology and exciton/charge carrier dynamics in bulk heterojunctions (BHJs) of the donor polymer PTQ10 and molecular acceptor IDIC are investigated. PTQ10:IDIC BHJs are shown to be particularly promising for low cost organic solar cells (OSCs). It is found that both PTQ10 and IDIC show remarkably high crystallinity in optimized BHJs, with GIWAXS data indicating pi‐pi stacking coherence lengths of up to 8 nm. Exciton‐exciton annihilation studies indicate long exciton diffusion lengths for both neat materials (19 nm for PTQ10 and 9.5 nm for IDIC), enabling efficient exciton separation with half lives of 1 and 3 ps, despite the high degree of phase segregation in this blend. Transient absorption data indicate exciton separation leads to the formation of two spectrally distinct species, assigned to interfacial charge transfer (CT) states and separated charges. CT state decay is correlated with the appearance of additional separate charges, indicating relatively efficient CT state dissociation, attributed to the high crystallinity of this blend. The results emphasize the potential for high material crystallinity to enhance charge separation and collection in OSCs, but also that long exciton diffusion lengths are likely to be essential for efficient exciton separation in such high crystallinity devices. [ABSTRACT FROM AUTHOR]

Boron doping with an adequate concentration is highly desirable for alloy development because it profoundly improves the material's interface cohesion via interfacial segregation. However, scientific and applicable potentials of soluble boron that resides at the alloy internal grains are generally overlooked. Here we report a strategy for overcoming the typically low strengths of face-centered cubic high-entropy alloys (HEAs) through exploiting soluble boron instead of the interfacial boron. We find that soluble boron increases stress/strain field at the recrystallized HEA grain structure, leading to the generation of short-range order (SRO) in those deformation structure under load at 77 K. The highly increased degree of SRO at planar dislocation slip band that forms during straining, proved by electron microscopy and synchrotron X-ray diffraction, strengthens a typical non-equimolar Fe 40 Mn 40 Co 10 Cr 10 (at%) HEA, particularly increasing yield strengths by ∼32%, to ∼1.1 GPa compared to those of boron-free reference materials with similar grain sizes. The advent of deformation-induced SRO domains causes severe lattice distortion (specifically, contraction), leading to the increased cryogenic yield strength of ∼210 MPa, but generating micro-voids at grain boundaries. This study on deformation-induced SRO via boron advances the fundamental understanding of SRO impacts on HEA grains and mechanical properties at cryogenic temperatures, which may pave a general pathway for developing a wide range of ultrastrong alloys for cryogenic applications. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Complex cation distribution in spinel solid solution, fosters defect generation and permutates the optical properties. To scrutinize the effect on structural properties, viz. the cation distribution and defect states upon substitution of Zn with Mg; and to tune the emission properties, Zn1−xMgxAl2O4 (0.01 ≤ x ≤ 0.30) nanocrystals are synthesized. The nanocrystals show increased inversion and generation of multiple defects, namely zinc vacancies, zinc interstitials, oxygen vacancies and antisite defects with increasing Mg content, which thereby impacts the optical band gap. Pentahedral coordination in addition to tetra- and octahedral coordination of Al has been observed, which infers the presence of oxygen vacancies and dangling bonds. Moire fringes formation has intimated the presence of two or more crystal lattices with higher Mg substitution. Band-to-band and defect-assisted photoluminescence shows the role of multiple defects, especially defect clusters, in deciphering the properties of the resulting crystals. Color change from bluish-white to pink has been achieved depending upon the excitation wavelength and emission mechanism, as proposed through a band model schematic. The presented study may be beneficial for designing the Zn1−xMgxAl2O4 nanocrystals with optimized emission properties. [ABSTRACT FROM AUTHOR]

Ga-doped ZnO (GZO)-graded layer, facilitating electron extraction from electron transport layer, was integrated on the surface of transparent indium tin oxide (ITO) cathode by using graded sputtering technique to improve the performance of planar n-i-p perovskite solar cells (PSCs). The thickness of graded GZO layer was controlled to optimize GZO–indium tin oxide (ITO) combined electrode for planar n-i-p PSCs. At optimized graded thickness of 15 nm, the GZO–ITO combined electrode showed an optical transmittance of 95%, a resistivity of 2.3 × 10−4 Ohm cm, a sheet resistance of 15.6 Ohm/square, and work function of 4.23 eV, which is well matched with the 4.0-eV lowest unoccupied molecular orbital of [6,6]-phenyl-C61-butyric acid methyl ester. Owing to enhanced extraction of electron by the graded GZO, the n-i-p PSC with GZO–ITO combined electrode showed higher power conversion efficiency (PCE) of 9.67% than the PCE (5.25%) of PSC with only ITO electrode without GZO-graded layer. In addition, the GZO integrated-ITO electrode acts as transparent electrode and electron extraction layer simultaneously due to graded mixing of the GZO at the surface region of ITO electrode. [ABSTRACT FROM AUTHOR]

Herein, we report the surface treatment on Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode for high-performance photoelectrochemical water splitting. A high-temperature quenching exhibits the Zr4+/Al3+ codoping in α-Fe 2 O 3 photoanode without damaging morphology. The presence of Zr4+/Al3+ codoping shows a cathodic shift in onset potential, but lack of increment in photocurrent reveals the major role of passivation and the minimum doping effect of aluminum. Additionally, CoO x cocatalyst exhibits increment in photocurrent with the greater cathodic shift in onset potential than the pristine α-Fe 2 O 3 nanorods. The CoO x surface-reworked Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode displays the highest photocurrent of 1.5 mA/cm2 at 1.23 V vs. RHE (76% increment over the pristine α-Fe 2 O 3) and 0.7 mA/cm2 at 1.0 V vs. RHE (102% increment over the pristine α-Fe 2 O 3). The systematic characterization carried out using x-ray diffraction and scanning electron microscopy confirms that after Zr4+/Al3+ codoping, and surface treatment, the crystalline structure, and morphology of the photoanodes remains unchanged. X-ray photoelectron spectroscopy confirmed the existence of Zr4+/Al3+ codopants in the hematite nanostructure. The electrochemical properties of the photoanode suggest that Al3+ and Zr4+ codoping, as well as surface treatment with CoO x , cocatalyst lowers charge transfer resistance across the FTO/hematite interface, and hematite/electrolyte interface. This designs not only lowers onset potential but also offers the blueprint for the development of an efficient catalyst for solar water oxidation. CoO x surface-reworked Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode displays the 102% increment in PEC performance than pristine α-Fe 2 O 3 at 1.0 V vs. RHE. Image 1 • Zr4+/Al3+-codoped Fe 2 O 3 photoanode synthesized by hydrothermal method. • CoO x co-catalyst improves the OER kinetics via surface reworking. • Optimum photoanode exhibits 102% increase in photocurrent density than Fe 2 O 3. • The charge transfer mechanism in 6% Zr + 6% Al + 15 mM Co is also proposed. [ABSTRACT FROM AUTHOR]