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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Correlative Microscopy Characterization of Cesium-Lead-Bromide Thin-films
摘要： Inorganic cesium lead halide compounds have gained an increasing interest in the perovskite photovoltaics research community. These compounds are mixed into state of the art organic lead halide perovskite solar cells to provide for more thermal stability, and CsPbX3 (x=I, Br, Cl) nanocubes are investigated as standalone emitter material in light emitting diodes. Eventually, reproducible, single-phase CsPbBr3 thin films could also provide us with a more stable inorganic material for perovskite solar cells. In the present work, we report on microscopic structural and optoelectronic properties of Cs-Pb-Br thin films prepared by different synthesis methods and studied using various electron-microscopy techniques.
关键词： cesium lead bromide,secondary phases,phase distribution,correlative microscopy,electron microscopy,halide Perovskites
更新于2025-11-21 10:59:37
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Phase Distribution and Carrier Dynamics in Multiple-Ring Aromatic Spacers-Based Two-Dimensional Ruddlesden-Popper Perovskite Solar Cells
摘要： Two-dimensional (2D) perovskites with natural multi-quantum-well structure have been reported to offer better stability compared to 3D perovskites. However, the understanding of the exciton separation and transport mechanism in 2D perovskite as well as developing more efficient organic spacers remain considerable challenges as the 2D perovskite exhibit large exciton binding energy due to quantum confinement. Here, a class of multiple-ring aromatic ammoniums, 1-naphthalenemethylammonium (NpMA) and 9-anthracenemethylammonium (AnMA), were developed as spacers for 2D Ruddlesden-Popper (RP) perovskite solar cells (PSCs). In addition to significantly enhanced stability, the device based on (NpMA)2(MA)n-1PbnI3n+1 (average n = 4) exhibits a champion efficiency of 17.25% and a high open circuit voltage of 1.24 V. The outstanding photovoltaic performance could be ascribed to the ultrafast exciton migration (within 7 ps) from 2D phases to 3D-like phases, which were confirmed by charge carrier dynamics results, leading to efficient exciton separation, charge transportation and collection. This work facilitates understanding the working mechanism of 2D PSCs deeply and offers an efficient way to further boosting their efficiency and stability by developing multiple-ring aromatic spacers.
关键词： perovskite solar cell,organic spacer,phase distribution,charge transport,two-dimensional
更新于2025-09-23 15:21:01
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Birefringence measurement of biological tissue based on polarization-sensitive digital holographic microscopy
摘要： We present a polarization-sensitive digital holography to measure the birefringence of biological tissues with complex structures. The birefringence measurement system is established by incorporating the modified Mach–Zehnder interferometer and lab-developed software. Normal and cancerous bladder tissue samples are measured by using the proposed experimental system. The polarization-dependent phase-shifted holograms are recorded by rotating the polarizer. Moreover, the hybrid reconstruction and least-square unwrapping algorithms are used to extract phase information of biological tissues at different polarization states. The birefringence of tissue is obtained from the above-phase distributions. The results show that polarization sensitivity exists in the normal bladder tissue and cancerous bladder tissue, and the median birefringence value of the cancerous tissue is significantly higher than that of the normal tissue. These results will provide reference for pathological research and clinic diagnoses.
关键词： Mach–Zehnder interferometer,birefringence,polarization-sensitive digital holography,biological tissue,phase distribution
更新于2025-09-23 15:21:01
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Coordination Engineering of Singlea??Crystal Precursor for Phase Control in Ruddlesdena??Popper Perovskite Solar Cells
摘要： 2D Ruddlesden–Popper perovskites (RPPs) have recently drawn significant attention because of their structural variability that can be used to tailor optoelectronic properties and improve the stability of derived photovoltaic devices. However, charge separation and transport in 2D perovskite solar cells (PSCs) suffer from quantum well barriers formed during the processing of perovskites. It is extremely difficult to manage phase distributions in 2D perovskites made from the stoichiometric mixtures of precursor solutions. Herein, a generally applicable guideline is demonstrated for precisely controlling phase purity and arrangement in RPP films. By visually presenting the critical colloidal formation of the single-crystal precursor solution, coordination engineering is conducted with a rationally selected cosolvent to tune the colloidal properties. In nonpolar cosolvent media, the derived colloidal template enables RPP crystals to preferentially grow along the vertically ordered alignment with a narrow phase variation around a target value, resulting in efficient charge transport and extraction. As a result, a record-high power conversion efficiency (PCE) of 14.68% is demonstrated for a (TEA)2(MA)2Pb3I10 (n = 3) photovoltaic device with negligible hysteresis. Remarkably, superior stability is achieved with 93% retainment of the initial efficiency after 500 h of unencapsulated operation in ambient air conditions.
关键词： 2D perovskites,coordination engineering,phase distribution,perovskite solar cells,single-crystals
更新于2025-09-23 15:19:57
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PROPERTIES OF AIRY-GAUSS BEAMS IN THE FRACTIONAL FOURIER TRANSFORM PLANE
摘要： An analytical expression of an Airy-Gauss beam passing through a fractional Fourier transform (FRFT) system is derived. The normalized intensity distribution, phase distribution, centre of gravity, e?ective beam size, linear momentum, and kurtosis parameter of the Airy-Gauss beam are demonstrated in FRFT plane, respectively. The in?uence of the fractional order p on the normalized intensity distribution, phase distribution, centre of gravity, e?ective beam size, linear momentum, and kurtosis parameter of the Airy-Gauss beam are examined in FRFT plane. The fractional order p controls the normalized intensity distribution, phase distribution, centre of gravity, e?ective beam size, the linear momentum, and kurtosis parameter. The period of the normalized intensity, phase, and centre of gravity versus the fractional order p is 4. The period of e?ective beam size, linear momentum, and kurtosis parameter versus the fractional order p is 2. The periodic behaviors of the normalized intensity distribution, phase distribution, centre of gravity, e?ective beam size, linear momentum, and kurtosis parameter can bring novel applications such as optical switch, optical micromanipulation, and optical image processing.
关键词： phase distribution,normalized intensity distribution,kurtosis parameter,centre of gravity,effective beam size,linear momentum,Airy-Gauss beam,fractional Fourier transform
更新于2025-09-10 09:29:36