Amine-based Molecule Interfacial Engineering For Efficient And Stable NiO_x-based Inverted Planar Perovskite Solar Cells

Recently,organic-inorganic hybrid perovskite has been widely studied due to its excellent photovoltaic performance and low-cost fabrication process.To date,the certified highest power conversion efficiency（PCE）of perovskite solar cells（PSCs）has reached 25.5%,which is comparable to the PCE of traditional silicon solar cells.The inverted planar PSCs,which employ nickel oxides（Ni O_x）as the hole transport layers（HTLs）and fullerene derivatives as the electron transport layer（ETLs）,have attracted the attention of researchers due to the low-temperature processability and simple fabrication process.There are two important interfaces in the Ni O_x-based inverted planar PSCs:Ni O_x HTLs/perovskite active layers and perovskite active layers/fullerene derivative ETLs.However,the lattice mismatch among Ni O_x HTLs and perovskite active layers will result in the formation of interfacial defects,which severely influences the hole transport and extraction at interface.Meanwhile,lots of defects exist on the surface of perovskite films because of the low-temperature solution preparation method,which will locate at the interface of perovskite/fullerene derivatives,resultantly,hindering the electron transport and extraction.Therefore,to improve the efficiency and stability of Ni O_x-based inverted planar PSCs,it is the key to passivate the interfacial defects for enhancing the charge transport and extraction at interface.In this thesis,amine-based molecular interface engineering is employed to improve the efficiency and stability of PSCs.We have developed the strategys to fabricate the efficient and stable Ni O_x-based inverted planar PSCs by coating iodinated amine-based interface molecule on the surface of Ni O_x and fumigating the perovskite films using amine-based interface molecules,respectively.The main contents are as follows:First,the Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃ perovskite/[6,6]-phenyl-C61-butyric acid methyl ester(PC₆₁BM)interface is modified by fumigating the perovskite films using amine-based molecules:butylamine（BA）,butanediamine（DAB）,diethylenetriamine（DETA）,triethylenetetramine（TETA）and tetraethylenepentamine（TEPA）,respectively.The results show that the fumigation of TETA and TEPA can effectively passivate the defects on the surface of perovskite films,reduce the carrier non-radiative recombination,optimize the interface energy level and improve the transport and extraction of electron.Through the fumigation of TEPA,the inverted planar PSC delivers a PCE of 20.47%with excellent humidity stability and thermal stability,in comparion with the PCE of 17.48%for the device without fumigation.Second,there iodinated amine-based molecules（BA·HI,DAB·HI and DETA·HI）are introduced into the Ni O_x/perovskite interface.The introduction of iodinated amine-based molecules can effectively promote the high-quality crystal nucleation,improve the crystallinity and the grain size of perovskite films,reduce the carrier non-radiative recombination,as well as promote carrier lifetime and suppress the interfacial defect formation.In addition,it is found that when the number of amino groups in the iodinated amine-based molecules increases,the effect is more significant.Moreover,upon introduction of DETA·HI,the inverted planar PSC delivers a high PCE of 20.43%with excellent humidity stability,compared with the device without modification（17.15%）.Our work provides a simple and effective amine-based molecule interface engineering to fabricate the efficient and stable Ni O_x-base inverted planar PSCs.