A novel perylene bisimide (PBI) dimer-based acceptor material, SdiPBI-S, was developed. Conventional bulk-heterojunction (BHJ) solar cells based on SdiPBI-S and the wide-band-gap polymer PDBT-T1 show a high power conversion efficiency (PCE) of 7.16% with a high open-circuit voltage of 0.90 V, a high short-circuit current density of 11.98 mA/cm(2), and an impressive fill factor of 66.1%. Favorable phase separation and balanced carrier mobilites in the BHJ films account for the high photovoltaic performance. The results demonstrate that fine-tuning of PBI-based materials is a promising way to improve the PCEs of non-fullerene BHJ organic solar cells.
The structural and electronic properties of the bulk and ultrathin black phosphorus and the effects of in-plane strain and out-of-plane electrical field on the electronic structure of phosphorene are investigated using first-principles methods. The computed results show that the bulk and few-layer black phosphorus from monolayer to six-layer demonstrates inherent direct bandgap features ranging from 0.5 to 1.6 eV. Interestingly, the band structures of the bulk and few-layer black phosphorus from X point via A point to Y point present degenerate distribution, which shows totally different partial charge dispersions. Moreover, strong anisotropy in regard to carrier effective mass has been observed along different directions. The response of phosphorene to in-plane strain is diverse. The bandgap monotonically decreases with increasing compressive strain, and semiconductor-tometal transition occurs for phosphorene when the biaxial compressive reaches −9%. Tensile strain first enlarges the gap until the strain reaches around 4%, after which the bandgap exhibits a descending relationship with tensile strain. The bandgaps of the pristine and deformed phosphorene can also be continuously modulated by the electrical field and finally close up at about 15 V/ nm. Besides, the electron and hole effective mass along different directions exhibits different responses to the combined impact of strain and electrical field.
A direct white-light metal-organic framework (MOF), [AgL](n) x nH(2)O (1, L = 4-cyanobenzoate), obtained by the reaction of deprotonated 4-cyanobenzoic acid and AgNO(3) in water, was found to exhibit tunable yellow-to-white photoluminescence by variation of excitation light. Interestingly, the close pure white emission of 1 has CIE-1931 chromaticity coordinates of (0.33, 0.34) when excited by 349-nm UV light, which is compatible to the light output of the deep UV LED.
Utilization of nonprecious transition metals for high alcohols synthesis is of a great importance in heterogeneous catalysis. We synthesized successfully cobalt metal-carbide (Co− Co 2 C) catalysts, which present remarkable activity and selectivity for high alpha-alcohols via the Fischer−Tropsch reaction. The formation of the stable cobalt carbide and the Co−Co 2 C interface are found to be essential for the observed reactivity. Density functional theory calculations show that Co 2 C is highly efficient for CO nondissociative adsorption, behaving as noble-metal-like, whereas the Co metal is highly active for CO dissociative adsorption and the subsequent carbon-chain growth. The interface between the cobalt metal and its carbide phase, as well as the dual sites available at the interface for facile CO insertion to hydrocarbon, could be used to rationalize the design of the nonprecious transition metal catalysts for the oxygenates in syngas conversion.
In-vitro metabolite and drug detection rely on designed materials-based analytical platforms, which are universally used in biomedical research and clinical practice. However, metabolic analysis in bio-samples needs tedious sample preparation, due to the sample complexity and low molecular abundance. A further challenge is to construct diagnostic tools. Herein, we developed a platform using silver nanoshells. We synthesized SiO2@Ag with tunable shell structures by multi-cycled silver mirror reactions. Optimized nanoshells achieved direct laser desorption/ionization mass spectrometry in 0.5 μL of bio-fluids. We applied these nanoshells for disease diagnosis and therapeutic evaluation. We identified patients with postoperative brain infection through daily monitoring and glucose quantitation in cerebrospinal fluid. We measured drug distribution in blood and cerebrospinal fluid systems and validated the function of blood-brain/cerebrospinal fluid-barriers for pharmacokinetics. Our work sheds light on the design of materials for advanced metabolic analysis and precision diagnostics.
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