Research On The Interfacial Connection Of Perovskite Solar Cells

Due to the excellent optoelectronic properties such as suitable band gap,long carrier life and high mobility,the photoelectric conversion efficiency(PCE) of perovskite material has increased from 3.8% to 25.5%in more than ten years.However,the stability of perovskite solar cells(PSCs) has limited commercial applications.The interface modification could improve the performance and stability of the devices by adjusting the function,passivating defects,preventing ion migration,and improving carrier dynamics.However,the comparison between different types of interface modification materials and the modification mechanism are still unclear.In view of this core scientific problem,the main research contents of this paper are as follows:(1)Study on the screening and mechanism of interfacial bridging materials for carbon-based PSCs(C-PSCs).The low cost and high stability of C-PSCs attract much attention,but the interface contact between perovskite and carbon electrodes results in the low efficiency of C-PSCs.The interface bridging method is the most effective method to improve the interface contact between perovskite layer and carbon electrode.By comparing four different bridging interface materials(carbon nanotubes,acetylene black,carbon nanotubes and graphene),we found that the function,conductivity and morphology of the interface modified materials are crucial to the performance of the devices.The results show that C-PSCs based on carbon nanotube bridging materials have higher photoelectric performance(15.09%).After 340 h of storage under strict environmental conditions(atmosphere,85?,65%relative humidity:RH),C-PSCs without any encapsulated carbon nanotube bridging could still retain 67%of the initial PCE value.(2)Comparison of dopant interface modified electron transport layer SnO₂ materials.Electron transport layer SnO₂ materials are widely used in PSCs,and there are many researches on its doping and interface modification,but there is no systematic comparison between the doping and interface modification,and its doping mechanism is not clear.In this paper,the interface modification is compared by doping elements of the same main group(LiCl,NaCl,KCl)and the same period(KCl,CaCl₂,GaCl₃)in the electron transport layer SnO₂.The results show that the doped elements do not enter the lattice of SnO₂.However,the electron transport layer of SnO₂ could be modified to obtain fewer crystal defects and better electrical conductivity.Compared with the doping of the same principal group and the same periodic elements,SnO₂-K has the smallest electron trap density.In our analysis,the main factor affecting the element doping is the electronegativity of ions.The low ionic electronegativity of K ions makes SnO₂ have better electron cloud density,higher electrical conductivity and lower electron trap density,so as to obtain better photovoltaic performance.The performance of the doped devices also proves that the KCl-doped SnO₂ devices have the best performance,achieving the highest efficiency of 20.92%.Stability test results showed that under the unencapsulated condition,the initial efficiency of 84.2% could be maintained in the dryer(25?,10%RH)for 1000 h.