Application Of Self-assembled Triarylamine Supramolecular Polymers In Perovskite Solar Cells

Perovskite solar cell（PSC）is an effective way to utilize solar energy,and the development of high-efficiency hole transport materials（HTM）and passivation materials is of great significance for improving the performance of perovskites.In this paper,two novel triarylamine derivatives were designed and synthesized,Amide triarylamine T1 and methoxy-triarylamine T2,The performance of self-assembled supramolecular polymers that is beneficial to hole transporting was studied.What is more,PSC devices were fabricated based on them as HTM and passivation material.The influences on device efficiency and stability were investigated,which provides new ideas for improving device performance.With tris（p-bromophenyl）amine,p-methoxyphenylboronic acid,bis（p-bromophenyl）amine,and p-methoxy iodobenzene as raw materials,T1 and T2 have been successfully synthesized through Gabriel synthesis methods,Suzuki reaction,Ullmann reaction and acylation reaction.The structures of target molecules and important intermediate products were identified by ¹H NMR,¹³C NMR and mass spectrometry.The self-assembly properties of compounds T1 and T2 were investigated by UV-Vis absorption spectroscopy,NMR spectroscopy and fluorescence emission spectroscopy.The results indicated that self-assembly of T1 and T2 were observed in chloroform solution under sunlight.The optimized molecular structure,electron cloud distribution and frontier molecular orbitals of molecular T1 and T2 were all studied by quantum chemical calculations.Afterwards,properties of electrochemistry,thermal stability and film-forming of the compounds T1 and T2 were tested respectively.It was indicated that both compounds can maintain good stability at high temperature,match with perovskite in term of energy level and have excellent hole mobility,7.09×10^-4 cm² V^-1 s^-1 and4.78×10^-4 cm² V^-1 s^-1 respectively.Therefore,both two compounds are potentially used as hole-transporting material（HTM）in perovskite solar cells（PSC）.Besides,it was found through atomic force microscopy that the Supramolecular polymers PT1 and PT2,formed by self-assembly of T1 and T2 respectively,both tend to form dense films.In addition,from X-ray photoelectron spectroscopy（XPS）,It can be indicated that the oxygen atoms in the molecule T1 coordinate with the uncoordinated Pb²⁺on the surface of the perovskite crystal,which can effectively suppress the surface defects of the perovskite and optimize the interface morphology between perovskite layer and hole-transporting layer.Based on T1 and T2 as HTM instead of 2,2’,7,7’-tetra[N,N-bis（4-methoxyphenyl）amino]-9,9’-spirodifluorene（spiro-OMe TAD）,PSC devices have only2.77%and 1.27%of power conversion efficiency（PCE）with 0.37 V and 0.21 V of open circuit voltages(V_OC),respectively.The results indicated that increased surface roughness of perovskite films treated by self-assembled T1 and T2 affected the interface contact between perovskite and HTM adversely to the disadvantage of hole transporting.After that,PT1 was used as passivation materials for the fabrication of PSC based on spiro-OMe TAD with those without passivation layer for comparison.The short-circuit current(J_SC),V_OC and PCE has increased by 1.46 m A cm^-2,0.01 V and 1.54%respectively.It is indicated that supramolecular polymer of T1 can effectively passivate defects in the perovskite layer and improve device performance,which has a good application prospect...