RESUMEN
Lead halide perovskite nanocrystals (NCs) exhibit great application potential in optoelectronic devices because of their tunable band gaps and facile colloidal synthesis, but they suffer from serious lead toxicity and instability. It is highly desirable to substitute lead with other elements to acquire nontoxic and environmentally friendly lead-free perovskite NCs for optoelectronic devices. Here, we report a general method for the colloidal synthesis of a series of bismuth/antimony-based halide perovskite NCs with various constituents and optical band gaps from 1.97 to 3.15 eV. In our proposed synthetic system, 1-dodecanol is adopted as the solvent instead of the conventionally used 1-octadecene to realize size controllability of bismuth/antimony-based metal halide perovskite NCs. It is found that 1-dodecanol can act as a surfactant to tightly adsorb on the surface of bismuth/antimony-based halide perovskite NCs, enabling their small sizes (â¼2 nm) and high dispersibility. Simultaneously, the band gaps of bismuth/antimony-based halide (A3B2X9, where A = CH3NH3, Cs, or Rb, B = Bi or Sb, and X = Cl, Br, or I) perovskite NCs can be systematically tuned by the atomic substitution of A, B, or X lattice sites. Moreover, to show the optoelectronic application potential of these lead-free halide perovskite NCs, a solar cell based on colloidal Cs3Bi2I9 perovskite NCs is demonstrated. The developed colloidal synthesis of bismuth/antimony-based halide NCs in 1-dodecanol will offer an alternative route to fabricating lead-free halide perovskite optoelectronic devices.
RESUMEN
Fabricating a robust interfacial layer on the lithium metal anode to isolate it from liquid electrolyte is vital to restrain the rapid degradation of a lithium metal battery. Here, we report that the solution-processed metal chloride perovskite thin film can be coated onto the lithium metal surface as a robust interfacial layer to shield the lithium metal from liquid electrolyte. Via phase analysis and density functional theory calculations, we demonstrate that the perovskite layer can allow fast lithium ion shuttle under a low energy barrier of 0.45 eV without the collapse of framework. Such perovskite modification can realize stable cycling of LiCoO2|Li cells with an areal capacity of 2.8 mAh cm-2 using thin lithium metal foil (50 µm) and limited electrolyte (20 µl mAh-1) for over 100 cycles at 0.5 C. The metal chloride perovskite protection strategy could open a promising avenue for advanced lithium metal batteries.
RESUMEN
A facile bottom-up strategy was developed to fabricate nitrogen-doped graphene sheets (NGSs) from glucose using a sacrificial template synthesis method. Three main types of nitrogen dopants (pyridinic, pyrrolic and graphitic nitrogens) were introduced into the graphene lattice, and an inimitable microporous structure of NGS with a high specific surface area of 504 m(2) g(-1) was obtained. Particularly, with hybrid features of lithium ion batteries and Faradic capacitors at a low rate and features of Faradic capacitors at a high rate, the NGS presents a superior lithium storage performance. During electrochemical cycling, the NGS electrode afforded an enhanced reversible capacity of 832.4 mA h g(-1) at 100 mA g(-1) and an excellent cycling stability of 750.7 mA h g(-1) after 108 discharge-charge cycles. Furthermore, an astonishing rate capability of 333 mA h g(-1) at 10,000 mA g(-1) and a high rate cycle performance of 280.6 mA h g(-1) even after 1200 cycles were also achieved, highlighting the significance of nitrogen doping on the maximum utilization of graphene-based materials for advanced lithium storage.