Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the ...Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.展开更多
Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel ...Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22273079)Fundamental Research Funds for the Central Universities(No.2682025ZTPY004)。
文摘Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.
基金supported by the National Key R&D Program of China(2016YFB070700702)the National Natural Science Foundation of China(51761145048)+1 种基金the Fundamental Research Funds for the Central Universities(HUST:2019421JYCXJJ004)the China Postdoctoral Science Foundation Grant(2019M662624).
文摘Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.
