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Solute structure and its evolution in supersaturated aqueous solutions are key clues to understand Ostwald’s step rule. Here, we measure the structural evolution of solute molecules in highly supersaturated solutions of KH2PO4 (KDP) and NH4H2PO4 (ADP) using a combination of electrostatic levitation and synchrotron X-ray scattering. The measurement reveals the existence of a solution-solution transition in KDP solution, caused by changing molecular symmetries and structural evolution of the solution with supersaturation. Moreover, we find that the molecular symmetry of H2PO4- impacts on phase selection. These findings manifest that molecular symmetry and its structural evolution can govern the crystallization pathways in aqueous solutions, explaining the microscopic origin of Ostwald’s step rule.The molecular symmetry of solute structure in aqueous solutions is a key clue to understand Ostwald’s step rule. Here, the authors show that molecular symmetry and its structural evolution can govern the crystallization pathways in aqueous solutions. [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]

Achieving highly effective catalytic activity in photoelectrochemical (PEC) water splitting has become a challenge in the fabrication of Fe2O3 photoanodes due to their poor electrical conductivity and surface charge recombination. This study outlines a one-step hydrothermal route for the design of surfactant-assisted in situ Au nanoparticle (NP)-integrated Zr-doped Fe2O3 photoanodes for PEC water splitting. A cetyltrimethylammonium bromide (CTAB) surfactant and Au-incorporated Zr-doped Fe2O3 photoanode achieved a photocurrent density of 2.30 mA cm−2 at 1.23 V vs. RHE (1.23 VRHE). CTAB promoted the adsorption of Au NPs on the Zr-FeOOH during the synthesis, while Au NPs accelerated the charge transfer kinetics. The loaded Au NPs enhanced the separation of photo-generated electron–hole pairs; as a consequence, Au NPs effectively shuttled the holes from the hematite to the photoelectrode/electrolyte interface, leading to improved photocatalytic activity. Further, the optimized Zr-HT/CTAB/Au photoanode exhibited an intrinsic solar-to-chemical conversion (ISTC) efficiency of 1.034%. Moreover, impressively, the deposition of a NiCo(OH)x cocatalyst enhanced the PEC performance to 2.72 mA cm−2 at 1.23 VRHE. This study presents a potentially fruitful strategy for simultaneous in situ decoration of a surfactant and Au NPs with photoanodes for PEC water splitting. [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]

A thin film of thermochromic VO2 was prepared on m-Al2O3 substrate using a radio frequency (RF) magnetron sputtering technique. The epitaxial growth of the monoclinic M1 phase of VO2 on the m-Al2O3 substrate was confirmed through synchrotron X-ray diffraction (XRD) measurements. The transformation of this monoclinic M1 phase into a rutile phase at ~68 °C was reflected in the temperature-dependent XRD measurements of the VO2 thin film. The temperature-dependent electrical resistance measurements of this sample also revealed an abrupt metal-to-insulator transition at ~68 °C, which is reversible in nature. Temperature-dependent X-ray absorption (XAS) measurements at V L-edge and O K-edge were performed to study the electronic structure of the epitaxial VO2/m-Al2O3 thin film during the metal-to-insulator (MIT) transition. [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]

To meet the requirements for indoor organic photovoltaic (OPV) applications, it is imperative to minimize charge recombination loss and enhance photovoltaic performance toward commercially compelling levels. Here, morphological modification in non‐fullerene blends is demonstrated to boost the efficiency and stability of indoor OPVs. For morphological modification, a ternary blend is devised by utilizing two well‐miscible non‐fullerene acceptors, which improve morphological features in the photoactive layer and suppress charge recombination loss. Morphological modification enhances OPV performance, particularly under low‐intensity indoor irradiation conditions, at which trap‐assisted recombination mainly governs the photovoltaic performance. The optimum ternary OPV shows a new record power conversion efficiency of 30.11% at a 500 lux light‐emitting diode, accompanied by excellent morphological durability under thermal stress, despite the use of "existing" photovoltaic materials designed for AM 1.5 G operation. This study elucidates the effects of morphology on OPV performance under low‐light conditions and suggests an ideal morphology for non‐fullerene OPVs with enhanced performance for indoor applications. [ABSTRACT FROM AUTHOR]

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]

Interface engineering is critical for reducing trap states present in various device interfaces and improving the efficiency of perovskite solar cells (PSCs). This study introduces the blending effect of poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) into metal‐phthalocyanine−tetrasulfonated acid tetrasodium salt (TS‐MPc) used as a hole transport layer (HTL) in organic–inorganic hybrid PSCs. PEDOT:PSS with a low pH induces the self‐assembly and formation of mesh‐like nano‐networks in a TS‐MPc layer, which is confirmed by atomic force microscopy and elemental mapping using energy‐dispersive spectroscopy. Compared with pure TS‐MPc, nano‐networked TS‐MPc with PEDOT:PSS exhibits higher crystallinity by grazing‐incidence wide‐angle X‐ray scattering. The nano‐network formation contributes to ≈30% enhancement in the power conversion efficiency (14.65%) of device with PEDOT:PSS‐assisted TS‐CuPc as HTL, compared with device using conventional PEDOT:PSS (11.02%). In addition, the device with PEDOT:PSS‐assisted TS‐MPc shows a significant improvement in stability owing to the reduced pH of the HTL compared with the device using pristine PEDOT:PSS. [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]

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]

The high pressure compression behaviors of two hydroquinone compounds have been investigated using a combination of in situ synchrotron x-ray powder diffraction and Raman spectroscopy up to ca. 7 GPa. The structural integrity of the α-form hydroquinone clathrate is maintained throughout the pressure range, whereas the CH4-loaded β-form hydroquinone clathrate decomposes and transforms to a new high pressure phase near 5 GPa. The bulk modulus (K) and its pressure derivative (K′) of the α-form and the CH4-loaded β-form hydroquinones are measured to be 8.2(3) GPa and 8.4(4), and 10(1) GPa and 9(2), respectively, representing one of the most compressible classes of crystalline solids reported in the literature. The corresponding axial compression behaviors, however, show greater contrast between the two hydroquinone compounds; the elastic anisotropy of the α-form is only marginal, being K(a):K(c)=1.08:1, whereas that of the CH4-loaded β-form is rather drastic, being K(a):K(c)=11.8:1. This is attributed to the different dimensionality of the hydrogen bonding networks between the two structures and might in turn explain the observed structural instability of the β-form, compared to the α-form. [ABSTRACT FROM AUTHOR]

Long-term stability of organic blends is a key factor for the practical use of organic solar cells (OSCs) in commercial fields. Here, we report the strategic incorporation of non-fullerene small molecules in polymer:fullerene blends to obtain ternary OSCs with improved efficiency and extended lifetimes. Non-fullerene small molecules employed in the polymer:fullerene blend successfully increased the photon-to-current conversion process as an efficient charge cascade acceptor. A combination of theoretical simulations and experimental measurements revealed that aggregation of meta-stable fullerene molecules was significantly alleviated in the ternary blend, thereby preventing an unintentional increase in the threshold for charge transfer during operation. Thus, the ternary OSCs could exhibit highly extended lifetimes with improved morphological stability and better resistance to performance decay under harsh real operational conditions compared to their binary counterparts. Combined with its high efficiency and improved device lifetimes, the high tolerance to the ternary blend thickness offers promise for commercially acceptable ternary OSCs fabricated by a printing process. [ABSTRACT FROM AUTHOR]

Pressure‐induced polymerization (PIP) of aromatics is a novel method for constructing sp3‐carbon frameworks, and nanothreads with diamond‐like structures were synthesized by compressing benzene and its derivatives. Here by compressing a benzene‐hexafluorobenzene cocrystal (CHCF), H‐F‐substituted graphane with a layered structure in the PIP product was identified. Based on the crystal structure determined from the in situ neutron diffraction and the intermediate products identified by gas chromatography‐mass spectrum, we found that at 20 GPa CHCF forms tilted columns with benzene and hexafluorobenzene stacked alternatively, and leads to a [4+2] polymer, which then transforms to short‐range ordered H‐F‐substituted graphane. The reaction process involves [4+2] Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the former is the key reaction in the PIP. These studies confirm the elemental reactions of PIP of CHCF for the first time, and provide insight into the PIP of aromatics. Short‐range ordered H,F‐substituted graphane was obtained by compressing benzene and hexafluorobenzene cocrystals. By using neutron diffraction and GC‐MS, the reaction process and elementary reactions were identified. The reaction process involves [4+2]Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the Diels–Alder reaction is the key reaction in the polymerization process. [ABSTRACT FROM AUTHOR]

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We investigated the effect of tension on the stable α-phase formation of nylon 5,6 fibers with two different drawing speeds using two-dimensional transmission wide angle X-ray scattering (2D WAXS) measurement. In an ex-situ condition, i.e., after releasing the applied tension and temperature, the relative amount of the α-phase in the fibers was higher at a higher drawing speed (57 mm/min). On the contrary, the development of the α-phase seemed faster and stronger during in-situ elongation of the fiber at a lower drawing speed (38 mm/min). The γ-phase, rather than the α-phase, played a key role in this complex behavior. The mechanical properties of the nylon fibers elongated under slow drawing speed (38 mm/min) were better than those elongated under a higher drawing speed (57 mm/min). The mechanical properties were more consistent in the case of α-phase formation in an in-situ condition under applied tension on the nylon fibers. Detailed structural information was obtained by quantitative analysis of the 2D WAXS data using an in-situ fiber drawing device. [ABSTRACT FROM AUTHOR]

Irradiation with much less than 1.0 keV H ions significantly improved the properties of IrMn-based spin valves. The giant magnetoresistance (GMR) was increased from 8.1% to 9.6% and the exchange bias field from 355 to 565 Oe after irradiation at 550 eV. The irradiation achieved even higher GMR than that achieved by field annealing: 9.6% vs 8.7%. We attribute this enhancement to strong (111) textures of the IrMn antiferromagnet and CoFe/Cu/CoFe/NiFe layers, as well as to a narrow mosaic spread of the (111) IrMn, both of which were developed by momentum transferred during the ion bombardment. The irradiated spin valve showed exchange bias as large as and (111) textures as strong as those of the field-annealed spin valve. The significant difference in the GMR values of the irradiated versus the field-annealed spin valves was probably due to different degrees of intermixing between layers. In the case of irradiation, the low energy of the lightest H ion likely resulted in little intermixing and, hence, the interfaces were largely left intact, which kept the GMR values high. [ABSTRACT FROM AUTHOR]

The development of new techniques that can be used to modify the molecular orientations and structures of organic compounds in organic thin films is in urgent demand to overcome the low levels of charge transport in such films and to ultimately achieve high-efficiency organic opto-electronics. Here, we report structural transformation and electrical characterization of a poly(3-hexylthiophene) (P3HT) semiconductor thin film under femtosecond laser irradiation at a level below the ablation threshold. A combination of grazing incidence X-ray diffraction and near edge X-ray absorption fine structure analyses reveal that the laser procedure effectively switches the P3HT orientation from edge-on to face-on, and the stability of this face-on orientation was also confirmed. Various laser fluence levels ranging up to the ablation threshold were tested, and the P3HT film with a transformed face-on orientation resulting from the optimized fluence level showed a charge current in the vertical direction three times greater than did the pristine film. This enhancement in the charge current was attributed to the vertical π–π stacking of the face-on orientation. These results also confirmed the effectiveness of our novel method for modifying organic thin films, and we expect this method to be attractive for the development of organic electronics and hybrid device applications. [ABSTRACT FROM AUTHOR]

Abstract: Nonfullerene acceptors (NFAs) in blends with highly crystalline donor polymers have been shown to yield particularly high device voltage outputs, but typically more modest quantum yields for photocurrent generation as well as often lower fill factors (FF). In this study, we employ transient optical and optoelectronic analysis to elucidate the factors determining device photocurrent and FF in blends of the highly crystalline donor polymer PffBT4T‐2OD with the promising NFA FBR or the more widely studied fullerene acceptor PC71BM. Geminate recombination losses, as measured by ultrafast transient absorption spectroscopy, are observed to be significantly higher for PffBT4T‐2OD:FBR blends. This is assigned to the smaller LUMO‐LUMO offset of the PffBT4T‐2OD:FBR blends relative to PffBT4T‐2OD:PC71BM, resulting in the lower photocurrent generation efficiency obtained with FBR. Employing time delayed charge extraction measurements, these geminate recombination losses are observed to be field dependent, resulting in the lower FF observed with PffBT4T‐2OD:FBR devices. These data therefore provide a detailed understanding of the impact of acceptor design, and particularly acceptor energetics, on organic solar cell performance. Our study concludes with a discussion of the implications of these results for the design of NFAs in organic solar cells. [ABSTRACT FROM AUTHOR]

The use of dry transferred graphene as a templating layer to enhance face-to-face stacking in poly(3-hexylthiophene) (P3HT) systems which is widely used for organic optoelectronics is investigated. In contrast to conventional poly(methyl methacrylate) (PMMA) assisted wet transferred graphene, dry transferred graphene is found in the current work to be quite suitable for use in the roll-to-roll process due to its lack of PMMA residue, whose removal would require high-temperature annealing. Grazing-incidence wide-angle X-ray scattering (GIWAXS) is used to determine the percentages of P3HT molecules adopting a face-on orientation on the various substrates tested. When a P3HT film with a thickness of 30 nm is produced, the face-on populations of P3HT are prominent on both the dry and wet transferred graphene layers. As the film thickness is increased to 50 nm, the face-on population decreases on the wet transferred graphene surface, but retains high levels on the dry transferred graphene. GIWAXS, near-edge X-ray absorption fine structure, and atomic force microscopy data are combined to propose schematic models for the molecular stacking of P3HTs on the two differently transferred graphene surfaces. [ABSTRACT FROM AUTHOR]

Tunable and selective areal polymer chain alignment method is developed for spin-cast blend films of poly(3-hexylthiophene)(P3HT):[6,6]-phenyl-C61-butlyric methyl ester (PCBM) system by a femtosecond laser process. The chain alignment, phase separation, and molecular structure of the laser exposed P3HT:PCBM films are investigated by grazing incidence wide angle X-ray scattering and micro-Raman analysis. The alkyl chains of P3HT polymer become highly ordered along the polarization axis of the laser. Thus, the amount of desirable face-on configuration for solar cell application is largely enhanced with a subsequent postannealing process. Vertically expanded morphology up to 200 nm on P3HT:PCBM films is also prompted by the laser irradiation without deteriorating intramolecular structure and changing chemical composition. Simultaneously, vertical phase separation of PCBM toward surface is induced at exposed region. [ABSTRACT FROM AUTHOR]

The structure of P3HT in P3HT:PCBM films is examined on a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) substrate subjected to cryo-cooling to low temperature (−143 °C) followed by gradual heating to 50 °C. The behavior of these systems is examined in the absence and presence of an Al electrode on top of the P3HT:PCBM film. At temperatures below −10 °C, only the type-I phase of P3HT is observed. However, the type-II phase of P3HT starts to form near −10 °C, in both the presence and absence of the Al layer. In the system without an Al layer, the type-II phase disappears at 30 °C, but this phase persists to 50 °C in the presence of the Al layer. Concomitant with the formation of the type-II phase, a 1:3 ordered P3HT type-II (1/3,0,0) superlattice peak emerged. The type-II domains tend to form near the Al electrode layer and show a higher degree of alignment than the type-I crystals. [ABSTRACT FROM AUTHOR]

In this study, we reported on the plasma damage-free sputtering of epitaxial Ga-doped ZnO (GZO) films on the p-GaN layer for use as a transparent contact layer (TCL) for GaN-based light-emitting diodes (LEDs) using linear facing target sputtering (LFTS). Effective confinement of high-density plasma between faced GZO targets and the substrate position located outside of the plasma region led to the deposition of the epitaxial GZO TCL with a low sheet resistance of 25.7 Ω/s and a high transmittance of 84.6% on a p-GaN layer without severe plasma damage, which was found using the conventional dc sputtering process. The low turn-on voltage of the GaN-based LEDs with an LFTS-grown GZO TCL layer that was grown at a longer target-to-substrate distance (TSD) indicates that the plasma damage of the GaN-LED could be effectively reduced by adjusting the TSD during the LFTS process. [ABSTRACT FROM AUTHOR]

This work reports the self-organization of dimple nanostructures on a polyethylene naphthalate (PEN) surface where an Ar ion beam was irradiated at an ion energy of 600 eV. The peak-to-peak roughness and diameter of dimple nanostructures were 29.1~53.4 nm and 63.4~77.6 nm, respectively. The electron energy loss spectrum at the peaks and troughs of dimples showed similar C=C, C=O, and O=CH bonding statuses. In addition, wide-angle X-ray scattering showed that Ar ion beam irradiation did not induce crystallization of the PEN surface. That meant that the self-organization on the PEN surface could be due to the ion-induced surface instability of the amorphous layer and not due to the partial crystallinity differences of the peaks and valleys. A nonlinear continuum model described surface instability due to Ar ion-induced sputtering. The Kuramoto–Sivashinsky model reproduced the dimple morphologies numerically, which was similar to the experimentally observed dimple patterns. This preliminary validation showed the possibility that the continuum equation used for metal and semiconductor surfaces could be applied to polymer surfaces where ion beam sputtering occurred. [ABSTRACT FROM AUTHOR]

Hole transport materials, perovskite solar cells, small molecule-polymer blend Keywords: hole transport materials; perovskite solar cells; small molecule-polymer blend EN hole transport materials perovskite solar cells small molecule-polymer blend 1 1 1 03/25/21 20210323 NES 210323 Water-soluble CuPc derivatives (TS-CuPc) have a self-assembly phase when present with PEDOT:PSS. Perovskite Solar Cells: Interface Engineering of Perovskite/Hole Transport Layer Using Nano-Network Formation in Small Molecule-Polymer Blend for Efficient Inverted Perovskite Solar Cells (Adv. [Extracted from the article]

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]

The figure illustrates the roll‐to‐roll transferred graphene combining with solution process aiming for flexible high efficiency devices by adopting MTG (molecular templating growth) effects of conjugated polymers on graphene surface. More details can be found in article number 1701099 by Jae‐Hyun Kim, Hyo Jung Kim and co‐workers. [ABSTRACT FROM AUTHOR]