富勒烯吡咯烷衍生物界面修饰材料在钙钛矿太阳能电池中的应用OA

[Objective]Currently,the widely used electron transport layer(ETL)in n-i-p type perovskite solar cells(PSCs)is tin oxide(SnO2).However,various defects are generated during the fabrication process of SnO2,which are detrimental to device performance.Therefore,it is of great importance to develop low-cost and solution-processable interface modification materials for SnO2.[Methods]Conventional n-i-p PSCs were fabricated with the structure indium tin oxide(ITO)/SnO2/CN-PP A/perovskite/Spiro-OMeTAD/Ag.SnO2 was spin-coated onto pre-cleaned ITO substrate at 5 000 r/min for 30 s using a SnO2 colloidal dispersion solution(diluted with deionized water in a volume ratio of 1∶3).After that,the substrates were annealed at 150 ℃ for 30 min.Then,CN-PPA(0.1 mg/mL in chlorobenzene)was spin-coated on the top of SnO2 layer at 3 000 r/min for 30 s and annealed at 100 ℃ for 10 min.The metal halide solution was prepared by dissolving PbI2 and CsI in a mixed solvent of N,N-dimethylformamide(DMF)and dimethyl sulfoxide(DMSO)(94∶6,by vol).The ammonium salt solution was prepared by dissolving formamidinium iodide(FAI)and methylamine hydrochloride(MACl)in isopropanol.To fabricate the perovskite layer,the metal halide solution was first spin-coated on the substrate at 1 500 r/min for 40 s.Subsequently,the ammonium salt solution was dropped at 1 800 r/min for 40 s.Afterwards,the perovskite layer was pre-annealed in a glove box at 90 ℃ for 1 min and then annealed at 150 ℃ for 10 min in ambient air with 30％-40％humidity.After cooling to room temperature,a phenethylamine hydroiodide(PEAI)solution(5 mg/mL in isopropanol)was further treated on the top of perovskite film.The Spiro-OMeTAD solution,consisting of 72.3 mg Spiro-OMeTAD,28.8 μL 4-tert-butylpyridine,17.5 μL Li-bis-(trifluoromethanesulfonyl)imide(Li-TFSI,520 mg/mL in acetonitrile)and 20 μL tris[2-(1 H-pyrazol-1-yl)-4-tertbutylpyridine]-cobalt(Ⅲ)tris[bis(trifluoro methylsulfonyl)imide](FK209,300 mg/mL in acetonitrile)in 1 mL chlorobenzene,was spun onto the perovskite film as a hole conductor.Finally,about 120 nm of Ag was thermally evaporated under high vacuum(2 × 10-4 Pa)to complete the device.[Results]CN-PPA can effectively fill the oxygen vacancy defects in SnO2 and bind with uncoordinated Sn4+.This could suppress the charge recombination at the interface,significantly improve the electron mobility of SnO2,and enable faster and more efficient electron transport at the interface,thereby enhancing the short-circuit current density and filling factor of PSCs.Consequently,the optimum power conversion efficiency(PCE)of PSCs with CN-PPA modification reaches 22.79％,which is higher than that of the control device based on SnO2(21.07％).[Conclusion]The fullerene derivative CN-PPA was synthesized by a one-step reaction and applied as an interfacial modification material in n-i-p type PSCs.Electron mobility and photoluminescence tests demonstrated that CN-PPA can improve the electron mobility of SnO2 ETL,enable more effective carrier transport at the interface of perovskite/ETL,and thereby enhance the efficiency of PSCs.This work offers valuable insights for the development of low-cost,solution-processable fullerene-based interface modification materials.