Effects Of Antions And Cations On Properties Of Perovskite Prepared By Vapor-solid Reaction Method

Power conversion efficiency?PCE?of organic-inorganic hybrid metal halide perovskite solar cells has exceeded 23%in past 10 years.However,the stability of perovskite solar cells?PSCs?and device size amplification are still obstacles to their commercial application.At present,perovskite solar cells are more suitable for solution preparation,but their industrial production is greatly restricted by solvent toxicity,device size constraints and harsh preparation conditions.Because it is more suitable to obtain high purity,large area thin film,and to finely control thin film thickness and surface morphology,all-vaccum vapor method has been widely used in semiconductor industry and optoelectronic field.From these aspects of stability of perovskite materials,preparation technology and perovskite materials composition optimization,in this paper,we carried out scanning electron microscope measure?SEM?,X-ray diffraction analysis?XRD?,X-ray photoelectron spectroscopy measure?XPS?,fluorescence spectrum measure and J-V curve measure to explore the preparation conditions and the principle that we can obtain efficient and stable large size perovskite solar cell module by solid-vapor reaction method.Started from the shallow to the deep,this parper is showed from the following four parts:1.By adjusting vapor-solid reaction temperature and cesium ion concentration,we found that when the reaction temperature was 160?and cesium ion concentration was 0.24,PCE of Cs_0.24FA_0.76PbI₃ perovskite solar cell device was up to14.2%.Under the condition of 30%humidity and 25?for 30 days,the devices still could maintain 80%of the initial efficiency.2.Combining with the advantages of chloride ions,a FACl-FAI multistage atmosphere reaction method was proposed.The first stage was to obtain FAPbI_3-xCl_x perovskite thin films in a low concentration of FACl atmosphere.In the second stage,colorless FA₂PbCl₄ perovskite thin films were generated in a high concentration of FACl atmosphere.The third stage was to obtain FAPbI₃ perovskite thin films in FAI atmosphere.In this way,uniform and compact perovskite films could be obtained.Based on FACl-FAI multistage atmosphere reaction method,we introduced cesium bromide into perovskite,and found that when the concentration of cesium bromide was 0.24,the perovskite device showed excellent performance,and PCE was over17%.We successfully fabricated a large size perovskite solar cell module with an efficiency of over 10%on a 5x5 cm² substrate.In addition,we found that there was a strong ion exchange process during the FACl-FAI multistage atmosphere reaction process,resulting in a very low concentration of bromine in the final perovskite film.3.By comparing the lattice constant of X-Cs_0.16FA_0.84PbI₃ perovskite?X=Na,K,Rb,Ba,In and Pd?with that of X-Cs_0.16FA_0.84PbI_3-yBr_y perovskite?X=Na,K,Rb,Ba,In and Pd?,we found the lattice constant of Na-Cs_0.16FA_0.84PbI_3-yBr_y perovskite,K-Cs_0.16FA_0.84PbI_3-yBr_y perovskite and Rb-Cs_0.16FA_0.84PbI_3-yBr_y perovskite decreased.The result of XPS further demonstrated that the decrease of lattice constant might be related with the increase of Br,which could indicate that Na⁺,K⁺and Rb⁺ions are beneficial to the stability of bromine in perovskite.4.From the two aspects of the changes in electronic transportation of material and the choice of metal cation species in perovskite,hysteresis phenomenon of PSCs was analyzed and discussed.we found that organic electron transport material of C₆₀could effectively restrain hysteresis of devices,and K⁺ions,or Rb⁺ion doping could also effectively eliminate the hysteresis of the device.The efficiency of the large-sized Rb-Cs_0.16FA_0.84PbI_3-yBr_y perovskite solar cell module prepared on the 8x8cm² substrate was up to 12.5%with no hysteresis.