Fabrication Of Flexible AgNW Composite Electrode With High Mechanical Robustness For Optoelectronic Application

In recent years,portable electronic products such as wearable electronic devices and mobile phones are developing towards flexibility,in which transparent electrode plays a crucial role as one of the indispensable core components.Different from the previous rigid devices,the transparent electrodes in flexible electronic devices should consider the mechanical flexibility under the premise of high conductivity and high light transmittance.Currently,the advantages of low sheet resistance and high light transmittance of indium tin oxide（ITO）make it the most commonly used electrode material.However,the inherent brittleness of ITO and the rarity of indium limit its development in flexible optoelectronic devices.With the rapid development of nanomaterials,flexible transparent electrodes based on metal nanowires have made great progress.Silver nanowires（AgNW）are considered to be the most promising alternative to ITO as a new generation of flexible transparent electrode materials due to their optoelectronic properties comparable to ITO.However,the problems of junction resistance and poor adhesion to substrates of silver nanowire network need to be solved urgently.In this paper,the problems affecting the optoelectronic properties of silver nanowire flexible transparent electrodes are studied.The main research contents are as follow:1.Two-dimensional（2D）titanium carbide（Ti₃C₂T_x MXene）nanosheets were prepared by chemical liquid-phase etching method.The Ti₃C₂T_x MXene dispersion was prepared by using the precursor titanium aluminum carbide（MAX-Ti₃Al C₂）as raw material and the mixture of hydrochloric acid and lithium fluoride and the strong acid hydrogen fluoride as etching agent,respectively.Ti₃C₂T_x MXene powder and few-layer dispersion were obtained by vacuum freeze-drying and intercalation.Based on scanning electron microscope（SEM）and energy dispersion spectrometer（EDS）,the crystal structure,morphology,element and atomic content of Ti₃C₂T_x MXene were analyzed and verified,and the Ti₃C₂T_x MXene with 2D structure was successfully prepared.2.Flexible AgNW transparent electrode with sheet resistance of 12.09Ω/sq and light transmittance of 81.96%were fabricated on polyethylene terephthalate（PET）by spin-coating method.After the introduction of 2D Ti₃C₂T_x MXene nanosheets on the flexible AgNW network,the flexible AgNW:MXene composite transparent electrode with a sheet resistance of 10.91Ω/sq and a light transmittance of 82.84%was prepared.The addition of Ti₃C₂T_x MXene nanosheets reduce the junction resistance of silver nanowire network,and the strong hydrogen bond between Ti₃C₂T_x MXene nanosheets and flexible PET substrate enhances the adhesion to the substrate.In addition,the high mechanical robustness of AgNW:MXene flexible composite electrode was verified by cyclic bending tests with different radius of curvature and monitoring at 120℃and 60%relative humidity.By analyzing the morphology,photoelectric and mechanical properties of the composite electrode,it is confirmed that Ti₃C₂T_x MXene nanosheets improve the performance of the flexible AgNW electrode.Finally,in order to verify the feasibility of AgNW:MXene flexible composite electrodes to replace ITO,AgNW:MXene flexible composite electrodes were applied to flexible perovskite solar cells（PSCs）and flexible organic photovoltaic cells（OPVs）,respectively.The high power conversion efficiency（PCE）of 20.22%and 16.03%was achieved on 0.1 cm²devices,respectively.And the corresponding mechanical properties have also been further improved.