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Development of the adaptive pattern synthesis method for accurate structured illumination by InYoung Park;Jonghee Yoon Optics and Lasers in Engineering 2022, 161(0); https://doi.org/10.1016/j.optlaseng.2022.107342 Abstract Structured illumination, which projects a predefined spatially varying intensity pattern, has been widely used in a variety of applications, including 3D shape estimation, optical property estimation, and super-resolution imaging. The precision of the structured illumination method is determined by the accuracy of the illumination pattern captured by the detector; however, acquiring images of the precise pattern is difficult due to distortion and nonlinear response in the imaging system. We proposed an adaptive pattern synthesis method that could overcome projecting system distortion and the system's nonlinear response. The proposed method consists of four steps: estimation of the geometric transformation matrix between the structured illumination unit and detector, estimation of the detector's intensity lookup table, and synthesis of the corrected patterns. Furthermore, by measuring the 3D printed target and tissue-mimicking phantom, the proposed method demonstrated its ability to improve the accuracy of phase shift profilometry and spatial frequency domain imaging. It does not require fine alignment or optical system details because all procedure is performed by projecting digital patterns and its measurement without calibration targets. The proposed method could be applied to any optical technique that uses structured illumination to improve accuracy and performance, making it useful in both academic and industrial applications. Keywords Structured illuminationSpatial frequency domain imagingPhase shift profilometryAdaptive opticsPattern correction
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- 작성일2023-01-16
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Surface activated zinc-glutarate for the copolymerization of CO2 and epoxides by Yongmoon Yang;Jong Doo Lee;Yeong Hyun Seo;Ju-Hyung Chae;Sohee Bang;Yeon-Joo Cheong;Bun Yeoul Lee;In-Hwan Lee;Seung Uk Son;Hye-Young Jang Dalton Transactions 2022, 51(0); https://doi.org/10.1039/D2DT03007A Abstract Zinc-glutarate (ZnGA) is a promising catalyst that can form polymers from CO2 and epoxides, thereby contributing to the development of CO2 utilization technologies and future sustainability. One of the obstacles to commercializing ZnGA in polymer industries is its low catalytic activity. In this study, we introduced activated two-dimensional (2D) ZnGA to improve its catalytic activity in polymerization. The morphology-controlled 2D ZnGA was treated with H3Co(CN)6, and a porous granular-type Co-modified ZnGA (Co-ZnGA) was prepared. The morphology of 2D ZnGA is a prerequisite for the activation by H3Co(CN)6. The catalytic properties of Co-ZnGA were evaluated by copolymerization of various epoxides and CO2, and exhibited catalytic activity of 855, 1540, 1190, and 148 g g-cat−1 with propylene oxide, 1,2-epoxyhexane, 1,2-epoxybutane, and styrene oxide, respectively. This study provided a new strategy using 2D ZnGA instead of conventional ZnGA for increasing the catalytic activity in CO2 polymerization.
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- 작성일2023-01-16
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Recent defect passivation drifts and role of additive engineering in perovskite photovoltaics by Ali Hassan;Zhijie Wang, Yeong Hwan Ahn;Muhammad Azam;Abbas Ahmad Khan;Umar Farooq;Muhammad Zubair;Yu Cao Nano Energy 2022, 101(0); https://doi.org/10.1016/j.nanoen.2022.107579 Abstract Rapid progress in the efficiency of hybrid lead halide perovskite photovoltaics surpassed the semiconductor thin-film solar cells such as CdTe (cadmium telluride), CZTS (copper zinc tin sulfide), and CIGS (copper indium gallium selenide) within a decade. Furthermore, low-cost solution processibility demonstrated the immense potential of perovskite solar cells (PSCs) as an alternative to commercially available light-harvesting materials. Despite the fast-track development in perovskite photovoltaic technology, several drawbacks are mainly linked with defects, including undercoordinated ions, band offsets, grain boundaries, photocurrent hysteresis, and environmental instability: restraint the industrialization of perovskite photovoltaics. Herein, we present the comprehensive knowledge of the source, nature, correlation with photophysical properties, and overlapping effects of these defects. The defects are categorized based on their energy levels within the conduction and valence bands, such as deep or shallow level defects, and their dimensionality (e.g., point defects such as vacancies, dislocation, grain boundaries, and cracks are regarded as zero-, one-, two-, and three-dimensional defects). Furthermore, we developed the fundamental understanding of defect-mediated, nonradiative recombination, ion migration, carrier trapping, and their cross-link with device performance and photocurrent hysteresis. Besides, an overview of topical defect passivation strategies on perovskite absorber, materials interface, charge transport layers, surface passivation, contact passivation, and additive engineering has been spotlighted. Finally, based on past and present defect healing drifts, we have summarized and recommended suggestions for next-generation PSCs, which will pave the way for swift industrialization. Keywords Perovskite solar cellsEnergy harvestingAdditive engineeringDefect passivationPhotovoltaics
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- 작성일2023-01-16
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Acceleration of Singlet Oxygen Evolution by Superoxide Dismutase Mimetics in Lithium–Oxygen Batteries. by Joo-Eun Kim;Hyun-Wook Lee;Won-Jin Kwak Advanced Functional Materials 2022, 32(52); https://doi.org/10.1002/adfm.202209012 Abstract Side reactions caused by reactive oxygen species (e.g., superoxide and singlet oxygen) are limiting factors in the lithium–oxygen batteries (LOBs). Superoxide dismutase mimetics (SODms), which suppress superoxide-triggered side reactions by accelerating the disproportionation reaction during discharge, are introduced as soluble additives in the LOBs. However, although SODms promote the disproportionation reaction, which is the main pathway for singlet oxygen evolution, the correlation between SODms and singlet oxygen has not been verified. Here, 4-carboxy-TEMPO is selected as a representative SODm that effectively promotes the disproportionation reaction and chemically verifies acceleration of singlet oxygen evolution. Furthermore, by using quencher, it is reported that the release of singlet oxygen evolved by the SODm is decreased. Because this study closely examines the relationship between the additives and singlet oxygen, it is believed that this study provides an important reference for the development of additives for the practical application of LOBs.
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- 작성일2023-01-16
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- 작성일2023-01-16
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Effects of Oxygen Vacancies in a Zinc Oxide Electron Transport Layer on Long-Term Degradation by Shin Young Ryu;Na Young Ha;Yeong Hwan. Ahn;Ji-Yong Park;Soonil Lee ACS Applied Energy Materials 2022, 5(8); https://doi.org/10.1021/acsaem.2c01325 Abstract We studied changes in current density–voltage (J–V) characteristics of organic solar cells (OSCs) with a ZnO electron-transport layer (ETL) with respect to illumination intensity and aging time. Unlike an encapsulated OSC that remained almost intact up to 195 h, an unsealed OSC showed steady degradation. To elucidate the origin of long-term degradation, we carried out systematic simulations and identified six parameters that were responsible for aging effects in dark J–V curves. Among these six parameters, additional adjustments were necessary only for donor density and energy-barrier height, both of which were linked to a ZnO ETL, to reproduce a set of J–V curves concomitantly measured at 12 illumination conditions. We note that oxygen vacancies in ZnO behave as electron donors and, additionally, result in dipole-moment losses. Consequently, reoxidation of a ZnO ETL resulted from slow diffusion of ambient oxygen or water, lowered the electron quasi-Fermi level, and increased the energy-barrier height. On the contrary, light-induced generation of oxygen vacancies, a short-term effect that disappears after turning illumination off, shifted the electron quasi-Fermi level upward and decreased the energy-barrier height. Because light-induced effects counteracted those of long-term reoxidation, light intensity-dependent variations in J–V curves became more prominent with aging. KEYWORDS: organic solar cell zinc oxide oxygen vacancy long-term degradation photo-induced effects
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- 작성일2023-01-16
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Polymorphism and sodium-ion conductivity of NaTa2PO8 synthesized via the Li+/Na+ ion-exchange reaction of LiTa2PO8 by Jaegyeom Kim;Junho Ha;Fouzia Khefif;Jong-Young Kim;Jae-Hwan Pee;Seung-Joo Kim Ceramics International, 2022, 48(14); https://doi.org/10.1016/j.ceramint.2022.04.052 Abstract Ion exchange reaction is a promising method to explore metastable compounds that could not be synthesized by conventional high-temperature solid-phase reactions. Herein, a new sodium tantalum phosphate, NaTa2PO8 was synthesized via the Li+/Na+ ion-exchange reaction of the parent compound, LiTa2PO8 in molten NaNO3 medium. NaTa2PO8 underwent an irreversible phase transition from the low- (LT-NaTa2PO8 to the high-temperature polymorph (HT-NaTa2PO8) at approximately 1000 °C. The crystal structures were solved using an ab initio structural determination method based on synchrotron X-ray powder diffraction data. The LT-NaTa2PO8 presented an orthorhombic structure, closely related to that of the parent LiTa2PO8 structure. In contrast, the HT-NaTa2PO8 was found to adopt a monoclinic structure, belonging to a family of monophosphate tungsten bronzes with pentagonal tunnels. The ionic conductivities of LT-NaTa2PO8 (σ = 5 × 10−5 S/cm at 309 °C) and HT-NaTa2PO8 (σ = 2 × 10−7 S/cm at 300 °C) exhibited Arrhenius behavior with activation energies of 0.49 and 0.79 eV, respectively. Bond valence energy landscape (BVEL) calculations indicated that a three-dimensional (3D) conduction pathway is formed in LT-NaTa2PO8 structure, while the conduction pathway in HT-NaTa2PO8 shows a two-dimensional (2D) character. Keywords Ion-exchangePolymorphismX-ray diffractionIonic conductivity
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- 작성일2023-01-16
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