Structure Design Of New-type Perovskite Materials And The Effect On Device Performance

Recently,organic-inorganic halide perovskite materials have become one of the most concerned materials in the field of optoelectronics due to their unique photoelectric characteristics.The certified power conversion efficiency(PCE)of perovskite solar cells(PSCs)which showed remarkable application prospect has reached 25.2%.However,the poor stability of perovskite devices is far from meeting the requirements of practical applications,which is one of the key factors hindering the further development of PSCs in the future.As the core component of the device,the instability of perovskite light absorbing layer materials under humidity,oxygen,heat and light conditions is the main cause of the instability of devices.Therefore,it is necessary to develop new-type perovskite materials and improve the efficiency and stability of devices through the structural design of materials.The appearance of two-dimensional(2D)and mixed-dimensional(MD)perovskite materials with excellent humidity stability has brought the dawn of the commercialization of PSCs,but the low PCE is an urgent problem to be solved.Based on the above research background and current situation,we mainly focused on the aspects of structure design of high-performance MD perovskite materials,studyed on the effects of halogenated ammonium on the properties of MD perovskite materials and preparation of efficient and stable 2D-3D PSCs.Aiming at improving the PCE of 2D and MD perovskite devices and studying effect of halogenated ammonium salts on the properties of 2D perovskite materials,we have carried out a series of research work:(1)Design of Cs doped benzylammonium(BE)-based MD perovskite.The photovoltaic performance and stability of BE-based MD perovskites were improved by inorganic cations Cs doping.The effect of the BE content on the crystallization,surface morphology,optical properties and the internal transport and recombination dynamics was studying.As a result,the PCE of the MD perovskite device with the optimal composition reached to 19.24%.Meanwhile,the humidity and thermal stability of BE/FA/Cs MD devices showed significantly improved than that of MAPbI3.(2)Cs doping and Br content regulation to design highly efficient and stable 2-hydroxyethylamine(HEA)-based MD perovskite materials.HEA was introducing into FA-based 3D perovskite as appropriate spacer cation.The Br component was further employed to improve the crystallization properties and surface morphology of MD perovskite films.The optical performance and defect density of the films with different component contents was systematically study.As a result,the optimal device with Cs doping and Br component displayed the PCE as high as 19.84%.The unencapsulated devices exhibited excellent thermal stability under 85? and enhanced moisture resistance under 55±5%RH.(3)Design of new-type MD perovskite materials based on halogenated ethylamine.To further improve the photovoltaic performance of MD perovskite devices,the effect of the chemical properties of organic ammonium salt on the performance of MD perovskite was studied.It can be found that the introduction of halogenated functional groups in organic ammonium salt could enhance the crystallization and inhibit the internal carrier recombination,resulting in the distinguished photovoltaic performance and the PCE as high as 20.08%.Meanwhile,due to the increased hydrophobic performance of the halogenated functional groups,the devices showed excellent humidity stability.(4)Study on the passivation of halogenated ammonium in MD perovskites.To further verify the passivation of 2D perovskite with halogenated ammonium,high-performance HEA-based quasi-2D PSCs were prepared by incorporating halogenated benzylammonium as second spacer cation.The mixed quasi-2D perovskites displayed superior crystallization and reduced internal defects,leading to enhanced charge transfer and suppressive carrier recombination.Finally,the PCE is increased from 15.19%to 18.75%,which layed a foundation for the application of halogenated low-dimensional perovskites.(5)Preparation of efficient and stable PSCs by interface treatment of halogenated low-dimensional perovskite materials(LDP).Based on the outstanding passivation effect of halogenated LDP,the LDP modified layers were designed to suppress nonradiative recombination and reduce trap density between perovskite and HTM layer,leading to significantly reduced voltage loss.Consequently,the optimal device showed a PCE of 21.13%.In addition,owing to the excellent hydrophobic performance of the LDP layer and the inhibition of ion migration at the interface,the humidity and thermal stability were significantly improved.The above research works not only improved the photovoltaic performance of MD perovskite through the structural design of perovskite materials,but also clarified the influence of halogenate ammonium on the performance and stability of 2D perovskite materials.Finally,2D-3D PSCs with the PCE over 21%and significantly improved stability were achieved.Our works provide the possibility for the development of highly efficient and stable 2D and MD perovskite materials,which can further promote the application and development of 2D and MD perovskite materials in the field of optoelectronics.