Enhanced proton irradiation resistance in Cs-doped CH_(3)NH_(3)PbI_(3) films and solar cells

Mixed-cation perovskite solar cells have attracted tremendous attention in space applications due to their excellent power conversion efficiency (PCE) and stability to light and heat.Although the evolution of photovoltaic performance in different space environments has been investigated,the role of inorganic cesium ions (Cs^(+)) in the enhancement of irradiation resistance needs to be further clarified.Herein,the structure and performance evolution of Cs-doped CH_(3)NH_(3)PbI_(3)(MAPbI_(3)) films and planar heterojunction devices under proton irradiation up to 1×10^(16)p cm^(-2) were studied.5%of Cs^(+) doping can increase the cohesive energy of MAPbI_(3)and effectively alleviate the lattice strain induced by proton irradiation,thereby enhancing the crystallinity and stability of films.The bandgap changes of irradiated Cs_(0.05)MA_(0.95)PbI_(3) films under the identical fluence were only one third of that of MAPbI_(3) films.Upon irradiation under the fluence of 1×10^(14)p cm^(-2),the density of trap states in the undoped and 5%Cs-doped films increased by 71%and 9%,respectively,and the average PCE of 20 corresponding devices decreased only by 12%and 9%,respectively.This proves that the replacement of organic methylamine ion with inorganic cesium ion contributes to the improvement of MAPbI_(3) resistance to proton irradiation,thus confirming the application prospects of mixed-cation or all-inorganic perovskite solar cells in spacecraft.

Enhancement of strength and electrical conductivity for a dilute Al-Sc-Zr alloy via heat treatments and cold drawing

Developing heat-resistant conductors with high strength and high electrical conductivity is a key issue in the electrical conductor industries, as the ever-increasing power transmission poses higher requirement on the thermal stability of electrical conductor wires. Dilute Al-Sc-Zr alloys are considered as promising candidates due to the excellent heat resistance and high electrical conductivity, but the low strength always limits their application on electrical wires. Yet, few efforts on process design have been made in dilute Al-Sc-Zr alloys to enhance the strength. Here, various kinds of processing paths via combination of cold drawing, ageing and/or annealing were conducted to improve the strength and electrical conductivity of a dilute Al-Sc-Zr alloy. Results show that enhanced strength and electrical conductivity were obtained after cold drawing + ageing or pre-ageing + cold drawing + annealing treatments processes.Optimal properties(194 MPa in ultimate tensile strength and 61% IACS in electrical conductivity) were obtained through cold drawing followed by ageing. Microstructure evolution which affects strength and electrical conductivity was systematically investigated using TEM and 3 DAP. The enhanced strength was mainly attributed to the suitable interactions between strain strengthening and precipitation strengthening. The enhancement in electrical conductivity was caused by precipitation of solute atoms and recovery of defects. These results provide foundations for the processing design of Al-Sc-Zr conducting wires with good properties and push forward their potential application in heat resistant conductor industries.

Effects of interfacial wettability on arc erosion behavior of Zn_(2)SnO_(4)/Cu electrical contacts

Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cubased composites under arc erosion.Exploring its influence mechanism,especially at atomic/electronic scales,is significant but challenging for the rational design of oxides/Cu contacts.Here,we designed Zn_(2)SnO_(4)/Cu electrical contacts aiming to solve the poor wettability of SnO_(2)/Cu composites.It was found that Zn_(2)SnO_(4)could remarkably improve the arc resistance of Cu-based electrical contacts,which was benefited by the excellent interface wettability of Zn_(2)SnO_(4)/Cu.The characterization of eroded surface indicated that Zn_(2)SnO_(4)particles distributed uniformly on the contact surface,leading to stable electrical contact characteristic.Nevertheless,SnO_(2)considerably deteriorated the arc resistance of SnO_(2)/Cu composite by agglomerating on the surface.The effect mechanism of wettability on arc resistance was investigated through density function theory(DFT)study.It revealed that strong polar covalent bonds across the Zn_(2)SnO_(4)/Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance.For binary SnO_(2)/Cu interface,ionic bonds resulted in weak interface adhesion,giving rise to deterioration of electrical contact characteristic.This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials.