Preparation Of MA₂SnI₆ Precursor Gel And Its Electronic Skin Application

Organic-inorganic hybrid perovskite materials?OIHPs?are a new type of photovoltaic material that has been widely used due to its many excellent properties.Due to the ionic composition of OIHPs,ion migration is prone to occur.This is often detrimental to electronic devices,but it also imparts some unique properties to OIHPs,such as ionic conductivity and the resulting changes in material resistance.Inspired by the excellent ion conductivity and low cost of ion skin,this paper studied the ion migration phenomenon in perovskite precursor materials,and successfully fabricated resistive electronic skin sensor by using its ionic conductivity and corresponding resistance change properties.For the first time,MA₂SnI₆ precursor gel?PPGel?and its MA₂SnI₆ single crystal were prepared by a simple solvent engineering strategy.The structure of the cross-linking between the fiber bundle and the agglomerate of the gel was observed by SEM,and the composition of the gel was studied by means of GIWAXS,Raman,infrared and EDS.The mechanism of gel formation was explained by UV-visible absorption,infrared and XRD data.The structure of MA₂SnI₆ crystal was determined by single crystal X-ray diffraction.The crystal is trigonal and the space group is R 3.The crystal cell side length is the sam and equal to 8.5165?6??.The crystal plane angle is 59.965?2?°.The unit cell volume is 436.45?9??³ and the density is 3.592 Mg/m³.The transient photovoltage data indicates that the MA₂SnI₆crystal is an N-type material.A band gap of 1.42 eV is obtained by the UV-visible absorption spetrum.The synthesized PPGel can be converted into a viscous liquid state by shaking or stirring,and then reversibly converted into a gel by standing for a few minutes.At the same time,it exhibits good wetting properties on the surfaces of different substrates such as PTFE,PDMS and PI,with contact angles of 74.3°,63.7°and32.1°,respectively;more importantly,PPGel has very good electrical conductivity.conductivity is 0.34 S·m^-1.Multi-response electronic skins capable of detecting pressure,vibration,temperature and electrical signals were successfully prepared using this gel.Among them,the GF is 3.38,the device is quite sensitive to recognize the finger bending angle,recognize the voice and monitor the pulse.And it has a negative temperature coefficient.The temperature sensitivity coefficient is-1.95%·^°C^-1?heating?,and the temperature sensitivity coefficient is-2.21%·^°C^-1?cooling?.This novel multi-function electronic skin sensor not only avoids the complex integration of several separate sensors,but also broadens the application of OIHPs derivatives to a whole new field,and broadens the range of choices for electronic skin sensing materials,in order to achieve low cost.A multi-functional electronic skin sensor that is non-toxic and simple in production process provides a reference.