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Femtosecond-laser-irradiation-induced structural organization and crystallinity of Bi2WO6
摘要： controlling the structural organization and crystallinity of functional oxides is key to enhancing their performance in technological applications. in this work, we report a strong enhancement of the structural organization and crystallinity of Bi2Wo6 samples synthetized by a microwave-assisted hydrothermal method after exposing them to femtosecond laser irradiation. X-ray diffraction, UV-vis and Raman spectroscopies, photoluminescence emissions, energy dispersive spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy were employed to characterize the as-synthetized samples. To complement and rationalize the experimental results, first-principles calculations were employed to study the effects of femtosecond laser irradiation. Structural and electronic effects induced by femtosecond laser irradiation enhance the long-range crystallinity while decreasing the free carrier density, as it takes place in the amorphous and liquid states. these effects can be considered a clear cut case of surface-enhanced Raman scattering.
关键词： structural organization,Bi2WO6,femtosecond laser irradiation,crystallinity,microwave-assisted hydrothermal method
更新于2025-09-23 15:19:57
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Impact of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays
摘要： Plasmonic nanohole arrays for biosensing applications have attracted tremendous attention because of their flexibility in optical signature design, high multiplexing capabilities, simple optical alignment setup, and high sensitivity. The quality of the metal film, including metal crystallinity and surface roughness, plays an important role in determining the sensing performance because the interaction between free electrons in the metal and incident light is strongly influenced by the metal surface morphology. We systematically investigated the influence of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays after different metal deposition processes. We utilised several non-destructive nanoscale surface characterisation techniques to perform a quantitative and comparative analysis of the Au quality of the fabricated sensor. We found empirically how the surface roughness and grain sizes influence the permittivity of the Au film and thus the sensitivity of the fabricated sensor. Finally we confirmed that the deposition conditions that provide both low surface roughness and large metal grain sizes improve the sensitivity of the plasmonic sensor.
关键词： sensitivity,Plasmonic nanohole arrays,biosensing,metal crystallinity,surface roughness
更新于2025-09-23 15:19:57
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Direct Observation of Crystal Engineering in Perovskite Solar Cells in a Moisture-Free Environment using Conductive Atomic Force Microscopy and Friction Force Microscopy
摘要： The origin of the increased efficiency of perovskite solar cells by control of environmental humidity was investigated using conductive atomic force microscopy (C-AFM) and friction force microscopy (FFM). The perovskite thin films fabricated in a humidity-free environment exhibited better crystallinity and lower number of trap sites than the films fabricated in a high-humidity environment. Through in-depth analysis using C-AFM and FFM, we found that there was locally decrystallized area in the perovskite structure fabricated in a high-humidity environment. By suppressing local decrystallization in a humidity-free environment, the power conversion efficiency (PCE) was increased by about 122%. This was mainly attributed to increase of the current density that elimination of the locally decrystallized area increase the effective active area. From this perspective, mapping local current and friction force using C-AFM and FFM could be new techniques for visualizing the effect of crystal engineering of perovskite solar cells in a humidity-free environment.
关键词： power conversion efficiency,crystallinity,perovskite solar cells,friction force microscopy,conductive atomic force microscopy,humidity
更新于2025-09-23 15:19:57
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Highly stable and efficient perovskite solar cells produced via high-boiling point solvents and additive engineering synergistically
摘要： The active absorber layer plays a crucial role in a perovskite solar cell. Herein, we used high boiling point γ-butyrolactone (GBL) as the main solvent, Pb(SCN)2 and dimethyl sulfoxide (DMSO) as an effective additive in the FA0.83MA0.17Cs0.05PbI(3?x)Brx solution to improve the quality of perovskite films. The GBL will delay the crystallization speed of the perovskite, and lead to the grain growth assisted by thiocyanate. The synergistic effect of the solvent engineering and additive engineering is beneficial to the slow growth of the grain size. It is found that the addition of Pb(SCN)2 increases Gibbs free energy barrier for the nucleation, leading to the formation of fewer nuclei, which results in a high quality of perovskite absorbers with larger grains and smoother surfaces. The synergistic effect of solvents and Pb(SCN)2 on the morphology and photovoltaic performances is investigated. Compared to devices without the additive, the efficiency of devices with 5% Pb(SCN)2-doped FA0.83MA0.17Cs0.05PbI(3?x)Brx is raised to 19.01% from 15.21%. We believe this breakthrough regarding high efficiency perovskite solar cells will help for their transitions.
关键词： efficiency,crystallinity,additive,perovskite,grain size
更新于2025-09-23 15:19:57
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a??Double-Acceptor-Typea?? Random Conjugated Terpolymer Donors for Additive-Free Non-Fullerene Organic Solar Cells
摘要： Random conjugated terpolymers (RCTs) not only promote great comprehension and realization for state-of-the-art high effective non-fullerene polymer solar cells (OSCs) but also offer a simple and practical synthetic strategy. However, the photovoltaic properties of RCTs yet lagged behind that of the donor-acceptor alternating copolymer, especially in the additive-free devices. Hence, we developed two feasible “double acceptor type” random conjugated terpolymers, PBDB-TAZ20 and PBDB-TAZ40. The additive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC exhibit decent efficiencies of 12.34% and 11.27%, respectively, which both surpass the PBDB-T:ITIC-based device. For the RCTs, the reasonably weakened crystallinity and reduced phase separation degree are demonstrated to help improve charge transport, reduce bimolecular recombination and thus enhance the photovoltaic performance of the additive-free OSCs. The results imply that adding a third moiety into the D-A polymer donors provides a simple but efficient synthetic approach for high-performance OSCs.
关键词： polymer solar cells,crystallinity,non-fullerenes,morphology,random terpolymers
更新于2025-09-23 15:19:57
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Delocalization boosts charge separation in organic solar cells
摘要： Organic solar cells (OSCs) utilizing π-conjugated polymers have attracted widespread interest over the past three decades because of their potential advantages, including low weight, thin film flexibility, and low-cost manufacturing. However, their power conversion efficiency (PCE) has been far below that of inorganic analogs. Geminate recombination of charge transfer excitons is a major loss process in OSCs. This paper reviews our recent progress in using transient absorption spectroscopy to understand geminate recombination in bulk heterojunction OSCs, including the impact of polymer crystallinity on charge generation and dissociation mechanisms in nonfullerene acceptor-based OSCs. The first example of a high PCE with a small photon energy loss is also presented. The importance of delocalization of the charge wave function to suppress geminate recombination is highlighted by this focus review.
关键词： Polymer crystallinity,Power conversion efficiency,Organic solar cells,Transient absorption spectroscopy,Dissociation mechanisms,Photon energy loss,π-conjugated polymers,Charge generation,Nonfullerene acceptor,Geminate recombination
更新于2025-09-23 15:19:57
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Over 14% Efficiency Nonfullerene All-Small-Molecule Organic Solar Cells Enabled by Improving the Ordering of Molecular Donor via Side-Chains Engineering
摘要： Improving the short current density (Jsc) is a big challenge for gaining highly efficient nonfullerene all-small-molecule organic solar cells (NFASM-OSCs). Herein, a novel small molecular donor, BT-2F which is derived from previously reported BTEC-2F, was designed and synthesized. The shortened alkyl-chains with higher regularity endow BT-2F with more ordered packing arrangement and more compact lamellar stacking as evidenced by the characterization of differential scanning calorimetry and grazing incidence X-ray diffraction. By blending BT-2F with Y6 or N3, BT-2F based devices showed impressive power conversion efficiencies (PCEs) of 13.80% and 14.09% respectively, much higher than the reported PCE of 13.34% for BTEC-2F:Y6. Besides, the efficiency of 14.09% is also among the highest PCE value reported so far for NFASM-OSCs. The distinctly improved Jsc devoted major efforts to enhancing the PCE values, meanwhile both BT-2F:Y6 and BT-2F:N3 still keep the high fill factors over 70%, which are ascribed to the good balance between high crystallinity and proper phase separation.
关键词： Morphology control,Crystallinity,Highly efficient nonfullerene organic solar cells,Molecular packing arrangement,Molecule design
更新于2025-09-23 15:19:57
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15.3% efficiency all-small-molecule organic solar cells enabled by symmetric phenyl substitution; ???????ˉ1?§°??§è?ˉ??o???é￥°?????°??????é??è??15.3%?????¨?°? ????-??????o?¤aé?3è????μ?±?;
摘要： Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells (NFSM-OSCs) due to the anisotropic conjugated backbones of both donor and acceptor. Therefore, developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials, and thus, enable the optimization of blend morphology is of vital importance. In this study, a new donor molecule B1, comprising phenyl-substituted benzo-dithiophene (BDT) central unit, exhibits strong interaction with the non-fullerene acceptor BO-4Cl in comparison with its corresponding thiophene-substituted BDT-based material, BTR. As a result, the B1 is affected and induced from an edge-on to a face-on orientation by the acceptor, while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results. It means the donor-acceptor blend morphology is synergistically optimized in the B1 system, and the B1:BO-4Cl-based devices achieve an outstanding power conversion efficiency (PCE) of 15.3%, further certified to be 15.1% by the National Institute of Me-trology, China. Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system, leading to the high-performance NFSM-OSCs.
关键词： all-small-molecule,intermolecular interaction,crystallinity,organic solar cells,non-fullerene
更新于2025-09-23 15:19:57
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Effects of TiO <sub/>2</sub> crystallinity and oxygen composition on forming characteristics in Pt/TiO <sub/>2</sub> /Pt resistive switching cells
摘要： “Forming” is a stage in resistive switching (RS) devices that occurs before switching and represents an important physical phenomenon in the universal operating mechanism of such devices. Forming in a resistance change material appears to be a kind of dielectric breakdown. In this study, we performed time-dependent forming (TDF) characterization of Pt/TiO2/Pt resistive switching cells with TiO2 layers of different crystallinities and oxygen compositions. We prepared two samples in which the grain boundary density and the density of oxygen vacancies differ, while both the TiO2 layers exhibited the similar crystal structures. Our results reveal that the Weibull slope and variation of time to forming are determined by the deposition method of the Pt bottom electrode (BE) ?lms. Moreover, the initial cell resistance and distribution of the TDF characteristics depend not only on the crystallinity but also on the oxygen composition of the TiO2 layers. The variation of time to forming increases as the distribution of initial resistance is reduced in Pt/NiO/Pt resistive switching cells with different NiO crystallinities. Conversely, the variation of time to forming decreases as the distribution of the initial resistance is reduced in the case of the Pt/TiO2/Pt cells. These results re?ect differences in both the grain boundary density (crystallinity) and the density of oxygen vacancies (oxygen composition) of resistance change materials used in the resistive switching cells. The clear difference of crystallinities and oxygen compositions might originate from differences in the oxide deposition mode during reactive sputtering.
关键词： oxygen composition,TiO2,forming,resistive switching,crystallinity
更新于2025-09-23 15:19:57
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Reflectance and crystallinity of silicon solar cells with LIPSS produced by XeCl excimer laser pulses
摘要： Laser-induced periodic surface structures (LIPSS) were formed on silicon solar cell surfaces by using a XeCl excimer laser to irradiate them with nanosecond UV laser pulses in the fluence range 0.2–0.6 J/cm2 near the melting threshold fluence (Fth = 0.5 J/cm2) in air. We measured the reflectance of the silicon solar cells after laser irradiation and evaluated their crystallinity by Raman spectroscopy. We found that reflectance and crystallinity depended on laser fluence and number of pulses. For fluence of 0.5 J/cm2, the produced LIPSS contributed to a reduction of ΔR = 3.3% in reflectance at a wavelength of 500 nm. The crystallinity of the fine structures with reduced reflectance was maintained at laser fluences near the melting threshold.
关键词： Crystallinity,Nanosecond UV laser,Reflectance,LIPSS,Nanostructured silicon solar cell
更新于2025-09-19 17:13:59