Synthesis And Optical Properties Of Two-dimensional Perovskite Materials

Perovskite materials,as excellent optoelectronic information materials,have attracted significant attention of researchers due to their fascinating optical and electric properties,resulting in unprecedented performances in solar cells,lasers,photodetectors.But unfortunately,perovskite materials are easy to be decomposed in the air environment,and the instabilities constrain their practical commercial application.Compared with traditional three dimensional perovskites,two-dimensional and Ruddlesden-Popper hybrid perovskites have demonstrated higher environment stability.Besides,two-dimensional perovskite has low defect densities and intrinsic quantum confinement effect.In parentheses,two dimensional perovskite materials are vital sources toward integrated,smaller,flexible and wearable device.Therefore,exploring the fundamental optical properties of two-dimensional perovskite is very important.Previous works have reported that the photoluminescence?PL?of the two-dimensional perovskite materials depends on temperature,thickness,doping or proportion of mixed halogens.However,to date,the manipulation of PL by magnetic and electric fields remains challenging.In this paper,three types of two-dimensional perovskite materials(including BA₂MAPb₂I₇,BA₂MAPb₂I₇-BA₂MA₃Pb₄I₁₃heterojunction and CsPbBr₃)have been systemically studied under external electric or magnetic field.The main contents are divided into three parts:?1?The two-dimensional layered perovskite BA₂MAPb₂I₇ was mechanically exfoliated from bulk crystals synthesized by a solution method.Then,the intensity and helicity parameter of the PL of bound exction are manipulated by external magnetic field due to?g-spin mixing effect.PL intensity decreases with increasing external magnetic field,and helicity parameter is linear with external magnetic field.In addition,the antimagnetic effect leads to a redshift of bound exciton.?2?Preparing two-dimensional Ruddlesden-Popper type perovskite heterojunction(BA₂MAPb₂I₇-BA₂MA₃Pb₄I₁₃)and studying the properties of PL.In this work,the PL intensity ratio between defect bound exciton and band-edge exciton of BA₂MAPb₂I₇ can be controlled by the heterojunction and external magnetic field,indicating that the generation of defects is suppressed by the heterojunction but promoted by the external magnetic field.?3?The PL emission of two-dimensional perovskite CsPbBr₃ was influenced by external in-plane electric field and the out-plane magnetic field.Zeeman splitting was observed in an external magnetic field,in which the energy splitting is enhanced and the PL peak is blue-shifted as the external magnetic field increasing.In addition,the external electric field can also make the PL peak bule-shift which is attributed to that external electric field can“heat”carriers,and giving rise to some hot carriers with higher energy.More interesting,a special phenomenon of energy splitting between right-handed and left-handed circularly polarized PL in an external electric field take place.The energy splitting only occurs in external negative?positive?electric field under left-?right-?hand circularly polarized light excitation.Our work provides numerous potentials for the two-dimensional perovskite materials application in optoelectronic devices,spintronic devices,and other fields.