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Novel report on luminescence, linear and laser induced optical traits of potassium aluminium sulphate crystal for photonic device applications
摘要： Optical quality inorganic crystals have emerged as a vital aspect for designing photonic devices hence in current investigation bulk size single crystal of potassium aluminium sulphate (KAS) has been grown by slow solvent evaporation technique. The crystalline phase of KAS crystal has been determined by means of powder X-ray diffraction analysis and its structural parameters have been experimentally determined by single crystal XRD technique. The optical transparency of KAS crystal has been examined within the wavelength range of 200-900 nm by employing the UV-visible spectral analysis. The color centered luminescence behavior of KAS crystal has been investigated within visible range of interest. The remarkable capability of KAS crystal to resist laser exposure has been determined using the pulse mode operated 1064 nm Nd:YAG laser. The third order nonlinear optical (TONLO) properties of KAS crystal have been examined at 640 nm and the nature of TONLO refractive index, absorption and susceptibility has been reported.
关键词： Crystal growth,Optical studies,Inorganic material
更新于2025-09-16 10:30:52
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Origin of Open‐Circuit Voltage Enhancements in Planar Perovskite Solar Cells Induced by Addition of Bulky Organic Cations
摘要： The origin of performance enhancements in p-i-n perovskite solar cells (PSCs) when incorporating low concentrations of the bulky cation 1-naphthylmethylamine (NMA) are discussed. A 0.25 vol % addition of NMA increases the open circuit voltage (Voc) of methylammonium lead iodide (MAPbI3) PSCs from 1.06 to 1.16 V and their power conversion efficiency (PCE) from 18.7% to 20.1%. X-ray photoelectron spectroscopy and low energy ion scattering data show NMA is located at grain surfaces, not the bulk. Scanning electron microscopy shows combining NMA addition with solvent assisted annealing creates large grains that span the active layer. Steady state and transient photoluminescence data show NMA suppresses non-radiative recombination resulting from charge trapping, consistent with passivation of grain surfaces. Increasing the NMA concentration reduces device short-circuit current density and PCE, also suppressing photoluminescence quenching at charge transport layers. Both Voc and PCE enhancements are observed when bulky cations (phenyl(ethyl/methyl)ammonium) are incorporated, but not smaller cations (Cs/MA)—indicating size is a key parameter. Finally, it demonstrates that NMA also enhances mixed iodide/bromide wide bandgap PSCs (Voc of 1.22 V with a 1.68 eV bandgap). The results demonstrate a facile approach to maximizing Voc and provide insights into morphological control and charge carrier dynamics induced by bulky cations in PSCs.
关键词： grain structure,perovskite solar cells,surface analysis,bulky cation additive,crystal growth
更新于2025-09-12 10:27:22
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lasers
摘要： The Tm,Ho:Lu2O3 crystal was grown by the optical floating zone method for the first time. The XRD pattern shows that it belongs to the cubic crystal system (Ia￣3 space group). The absorption cross-section at 796 nm is 10 21 cm2, the full width at half maximum (FWHM) is 54 nm. The emission cross-section at 2092 nm is 4.21 2. The broad fluorescence band extends to 2200 nm where almost no absorption was found. The fluoresce lifetime at 2092 nm is 3.73 ms. With the help of up-conversion spectra, the energy transfer mechanism between Tm3+ and Ho3+ ions was investigated systematically. The potential utility of the Tm,Ho:Lu2O3 crystal as tunable and ultra-short laser media at ~2.1 μm can be expected.
关键词： Lu2O3,Ho3+ ions,Crystal growth,Tm3+ ions
更新于2025-09-12 10:27:22
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nanocrystal-based film for solar cell
摘要： In recent years, energy harvesting through photovoltaic has emerged as promising and long-term technology for energy production. However, for commercial applications, the fabrication of a photovoltaic solar cell requires an easy and low-cost process compatible with large-area and high-throughput production. In this work, we demonstrate a simple and fast light sintering technique for Cu2ZnSnS4 (CZTS) nanocrystal-based film. The CZTS nanocrystal-based film was irradiated with various intensity of light to observe the sintering effect. The significant sintering of CZTS film was achieved by irradiating with light intensity of 2.23 J/cm2 for 200 microseconds. The solar cell fabricated with light sintered CZTS nanocrystal-based film exhibited efficiency of 1.9% with open circuit voltage of 0.50 V and short-circuit current density of 11.5 mA/cm2 with fill-factor of 0.33. The light sintering technique can be further optimized for large-area sintering of nanostructures for various applications.
关键词： Sintering,Thin films,Deposition,Solar energy materials,Crystal growth
更新于2025-09-12 10:27:22
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Precise stress control of inorganic perovskite films for carbon-based solar cells with an ultrahigh voltage of 1.622?V
摘要： All-inorganic cesium lead bromide (CsPbBr3) perovskite solar cell is one promising candidate to balance high efficiency and poor stability of organic-inorganic hybrid photovoltaics. The charge carrier transport can be maximized for high-efficiency devices through precise stress control during perovskite grain growth process to obtain high-quality full-bromine CsPbBr3 halide films. We present here the monolayer-aligned and large-grained CsPbBr3 perovskite films through precise control of crystallization temperature of PbBr2 film because the lattice volume is enlarged by 2.18 times during the phase conversion from PbBr2 to CsPbBr3, which helps to minimize residual-stress-induced grain boundaries and defect-induced charge recombination. Upon further interfacial modification by nitrogen doped carbon quantum dots, the hole transporting materials free, all-inorganic CsPbBr3 perovskite solar cell achieves a champion efficiency as high as 10.71% with an ultrahigh open-circuit voltage of 1.622 V. Moreover, the unencapsulated solar cell demonstrates remarkable long-term stability in 85% humidity in air atmosphere.
关键词： Stability,Strain engineering,Crystal growth,Cesium lead bromide,Charge recombination,Inorganic perovskite solar cell
更新于2025-09-12 10:27:22
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Well-grown low-defect MAPbI3–xClx films for perovskite solar cells with over 20% efficiency fabricated under controlled ambient humidity conditions
摘要： The conventional MAI [(CH3NH3I (MAI)):PbI2:PbCl2= 3 : 0 : 1 [abbreviated as (3:0:1)]] precursor solution is known to result in CH3NH3PbI3–xClx films with large grain sizes when processed in an inert atmosphere, but it gives non-uniform perovskite films containing lots of voids and cracks when processed in ambient air. Furthermore, a dramatically longer annealing time (usually 100 min) is required for these films (3:0:1) due to the slow formation of the MAPbI3 phase via MACl loss, which is not conducive to perovskite film formation under ambient conditions due to perovskite degradation upon long exposure to moisture. Pure MAPbI3 films can be formed very rapidly from (1:1:0) (MAI:PbI2:PbCl2= 1 : 1 : 0) solution within a short annealing time, but they show small grain sizes and poor film quality. This work demonstrated that a fractional substitution of PbI2 with PbCl2 in the ([MAI]:[PbI2]= 1 : 1) precursor solution has a significant influence on film morphology and quality in terms of crystallization rate, grain size, crystallinity, and trap density of the formed perovskite film. Perovskite films can be formed with 5-min annealing at 100 °C from the precursor (MAI: PbI2:PbCl2= 1: 0.8 : 0.2) processed in ambient air (humidity, 20% RH), exhibiting more uniform, increased grain size and higher film quality with reduced trap densities compared to film (1:1:0), thus leading to significantly improved power conversion efficiency (PCE), from 16.7% for perovskite solar cells (PrSCs) based on film (1:1:0) to 20.04% for the cell based on film (1:0.8:0.2). Further, the effects of R (R= [MAI]/[PbI2+PbCl2]) on morphology, hole mobility, carrier lifetime and efficiency of PrSCs were systematically and thoroughly investigated. This study found that MAPbI3–xClx at R=1 can enable the highest hole mobility and longest carrier lifetime, thus giving the best performance at R=1.
关键词： mixed halide perovskite solar cells,lead chloride,grain size,trap density,crystal growth intermediates
更新于2025-09-12 10:27:22
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Growth Promotion of Targeted Crystal Face by Nano-Processing via Laser Ablation
摘要： Control of crystal shape is an indispensable step for various applications of crystalline products. However, obtaining the desired crystal shape by conventionally tuning environmental conditions (temperature, additives, etc.) cannot always be reached. Recently, we have developed an innovative approach for spatiotemporal control of crystal growth of proteins and amino acids by locally modifying crystal structure (e.g., formation of screw dislocations) via femtosecond (fs) laser ablation. In this work, to clarify the appropriate laser condition for controlling the shape of single crystals with minimized damage, we first systematically investigated the dependence of pulse duration on laser ablation and crystal growth of L-phenylalanine (L-Phe). By using a laser system with tunable pulse durations from fs to nanosecond (ns), we found fs laser ablation can offer nanometer-sized, sharp etching of which diameter was smaller than the diffraction limit. By utilizing such nano-processing via fs laser ablation for promoting the growth of a targeted crystal face, we successfully demonstrated the preparation of a bulky crystal of L-Phe, which are difficult to be obtained by conventional crystallization methods.
关键词： L-phenylalanine,nano-processing,single crystal growth,crystal shape control,femtosecond laser ablation
更新于2025-09-11 14:15:04
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Evaluation of exciton diffusion length in highly oriented fullerene films of fullerene/p-Si(100) hybrid solar cells
摘要： Highly oriented fullerene (C60) films on p-Si (100) substrates were fabricated to evaluate the crystallinity dependent exciton diffusion length of C60 (LC60). The crystal structure of the C60 films was examined using grazing incidence X-ray diffraction (GIXD). The results of an in-plane rocking scan and a pole figure suggested that a 12-fold-symmetry crystal was grown with the C60(111) surface interfaced to the Si(100) substrate. The photovoltaic characteristics of the oriented C60/p-Si(100) hybrid solar cells were evaluated. A masking effect was clearly evident in the incident photon-to-current conversion efficiency (IPCE) spectra. LC60 was evaluated using both experimental IPCE spectra and that produced by one-dimensional-optical simulation. It was concluded that LC60 for highly oriented C60 was 60 nm, which was longer than that of disordered C60 films.
关键词： crystal growth,hybrid solar cells,fullerene (C60),exciton diffusion length,grazing incidence X-ray diffraction (GIXD),masking effect
更新于2025-09-11 14:15:04
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Surface Capping Agents and Their Roles in Shape‐Controlled Synthesis of Colloidal Metal Nanocrystals
摘要： Controlling the shapes and related properties of colloidal metal nanocrystals are key to the realization of their vast applications. Surface capping agents, including neutral molecules, ionic species, macromolecules, and biomolecules, have been extensively used to control the evolution of seeds into nanocrystals with diverse but well-controlled shapes. Here we offer a comprehensive review of these agents, with a focus on the mechanistic understanding of their roles in guiding the shape evolution of metal nanocrystals. We begin with a brief introduction to the early history of capping agents in electroplating and bulk crystal growth, followed by discussion of how they affect the thermodynamics and kinetics involved in a synthesis of metal nanocrystals. We then present representative examples involving both experimental and computational studies to highlight the various capping agents, including their binding selectivity, molecular-level interaction with a metal surface, and impacts on the growth of metal nanocrystals. We also showcase progress in leveraging capping agents to generate nanocrystals with complex structures and/or enhance their catalytic properties. Finally, we discuss various strategies for the exchange or removal of capping agents, together with perspectives on future directions.
关键词： shape control,structure-property relationship,crystal growth,metal nanocrystal,Capping agent
更新于2025-09-11 14:15:04
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In situ reflection imaging and microspectroscopic study on three-dimensional crystal growth of L-phenylalanine under laser trapping
摘要： We investigate growth behavior of an L-phenylalanine crystal formed by laser trapping with the use of reflection imaging and microspectroscopy. Optical reflection micrographs show colored images of the crystal due to constructive interference of incident white light. The color distribution on the crystal is dynamically changed under laser trapping, which is in addition to enlargement of the crystal plane area. The temporal change in the crystal thickness is examined by measuring reflection spectra of the crystal. We discuss the three-dimensional crystal growth under laser trapping by comprehensively considering the changes in crystal thickness and crystal plane area.
关键词： reflection imaging,laser trapping,L-phenylalanine,crystal growth,microspectroscopy
更新于2025-09-11 14:15:04