The Effect Of Ferroelectric Polarization On The Interfacial Carrier Transport Properties For Perovskite-based Heterostructure

Due to the suitable bandgap,high absorption coefficient,longer carrier diffusion length and other excellent properties,the perovskite materials have gained wide attention in photovoltaic field.In order to study interfacial carrier behavior of the ferroelectric/perovskite heterojunction,we built PVDF/MAPbI₃ and BaTiO₃/FAPbI₃ heterostructures,and density functional theory is used to study the effect of different ferroelectric polarization on carrier transfer of interfacial structures.We discovered the ferroelectric polarization direction can lead to band offset in two heterostructures,which means the ferroelectric polarization can be used to control the transfer direction of carrier in perovskite slab.The main work is as follows:Interfacial interactions between interfacial atoms of PVDF/MAPb I₃ heterostructures were analyzed by bond lengths,electron localization function and Bader charge.The calculation results show that PVDF/MAPbI₃ interfacial heterostructures formed by Van der Waals interactions.Difference charge density indicate that ferroelectric polarization can effectively control the direction of electron transport at the interface.Ferroelectric polarization(P_down)induced by F atoms layer of PVDF contacting to MAPb I₃ can promote the charge transfer from MAPb I₃ into PVDF,however,ferroelectric polarization(P_up)induced by H atoms layer of PVDF contacting to MAPbI₃ can drive charge transfer from PVDF into MAPb I₃.By studying the electronic density of states projected on real space,it can be concluded that the inclined band formed in heterojunctions,which promotes the separation of photo-induced carrier.The transfer mechanism of electron in excited states is simulated,and the ferroelectric polarization can play a switching role in electron transport.We built the inorganic ferroelectric BaTiO₃/FAPbI₃ interfacial heterostructures,and the interfacial interactions of four interfaces were analyzed by bond length and electron localization function.The results indicate that BaTiO₃/FAPbI₃ interfacial heterostructures formed by different chemical interactions.Difference charge density show that ferroelectric polarization induced by BaTiO₃ exposed surface?BaO and TiO₂?can control the electron transport direction at the interface,BaO/FAPbI₃ interfacial structure can promote electron transfer from BTO to FAPb I₃,and TiO₂/FAPbI₃ layer interfacial structure can drive electron transfer from FAPbI₃ to BTO.Through the analysis of electronic density of states projected on real space,we discovered the band alignment of TiO₂/FAPbI₃ heterostructure can accelerate the separation of photo-induced carrier and the transfer and extraction of electrons.