A First-Principle Study On The Surface Adsorption Characteristics Of Perovskite Materials

With the improvement of living standards,people pay more attention to the detection of harmful gases.Gas sensors are used to detect these toxic gases.Among them,sensors based on perovskite materials have become a kind of promising gas sensing material for their low cost,nice performance at room temperature and good sensitivity.Experiments have been carried out with different types of perovskite materials for different gases,and good results have been obtained.Due to the lack of mechanism guidance,the current trials of perovskite gas sensing materials generally use trial and error.However,the typical feature of AnBXm perovskite materials is that the element of A、B、X can be replaced or doped.Thousands of candidate materials can be designed only by changing the B-site metal ions.The trial and error method not only waste manpower and material resources,but also greatly prolongs the material development cycle.The development and design of gas sensing materials guided by the sensitivity and selectivity mechanism of semiconductor material surface to gas molecules can effectively speed up research speed and shorten the development cycle.Therefore,this paper uses a combination of static and dynamic quantum mechanical simulation to simulate different types of perovskite materials adsorbing different gases,systematically study the structural changes of perovskite in the dynamics process.The interaction process and the accompanying adsorption energy change and charge transfer analysis and comparison between gas and perovskite.The adsorption characteristics model of different properties of gas on the surface of perovskite material is established,and the gas sensing mechanism of perovskite material is revealed.In this paper,the dynamics method combined with the first-principles calculation is performed to simulate the adsorption of different gases on different types of perovskite materials,we analysis the structural changes in the process of dynamics simulation,the interaction process between gases and perovskites and the accompanying adsorption energy and charge transfer between gases and perovskite materials.The theoretical analysis and calculation agree well with the experimental results.Our simulations are carried out with these two type of perovskite materials:MAPbI3 and(MA)2Pb(SCN)2I2,we choose H2O to adsorb on MAPbI3 materials,CO(CH3)2,H2O,NO2 and O3 as the gas models to adsorb on the(MA)2Pb(SCN)2I2 materials.When H2O adsorbs on these two perovskite materials,the structure of(MA)2Pb(SCN)2I2 is more-stable due to the stronger interaction of Pb-SCN.Therefore,the water has less damage to it during the simulation,the structure of MAPbI3 suffer more damage as a comparison;when(MA)2Pb(SCN)2I2 adsorbs H2O,CO(CH3)2,NO2 and O3 individually,The severity of the damage to(MA)2Pb(SCN)2I2 is obviously related to the adsorbed gas.The stronger the gas oxidation become,the stronger the interaction with the perovskite is,and more charges are transfer between gas and(MA)2Pb(SCN)2I2,therefore the gas causes stronger damage to the perovskite,which corresponding to lower minimum detection concentration of the gas.Our results provide theoretical basis for explaining and predicting the adsorption mechanism and minimum detection concentration of different gases adsorb on perovskite materials.Besides,they also provides reference to the application of other materials used as gas sensing materials.