自组装单分子层添加剂提升钙钛矿太阳能电池的性能OA

[Objective]In the study of inverted perovskite solar cells(PSCs),the poor interfacial contact between the self-assembled monolayers(SAM)and the buried interface of the perovskites leads to issues such as increased defects and charge carrier recombination.Thus,optimizing the SAM/perovskite buried interface is crucial for fabricating highly efficient and stable PSCs.[Methods]The etched indium tin oxide(ITO)glass was sequentially ultrasonically cleaned with detergent,deionized water,acetone,and isopropanol for 20 min.After drying with N2,the cleaned ITO glass was treated with UV-ozone for 10 min.Then,NiOx(15 mg/mL in H2O)was spin-coated on the ITO substrate at 2 000 r/min and annealed at 150 ℃ for 10 min.After cooling to room temperature,the[2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid(MeO-2PACz)or 5,6-dichloro-pyrazine-2,3-dicarbonitrile(DCP)doped MeO-2PACz was spin-coated onto the NiOx layer at 4 000 r/min and annealed at 100 ℃ for 10 min.The perovskite precursor was prepared by mixing PbI2,PbBr2,FAI,MAI,and CsI with the formula of(FA0.95MA0.05)0.95Cs0.05Pb(I0.95Br0.05)3(1.4 mol/L)in the mixed solvent of V(N,N-dimethylformamide)∶V(dimethyl sulfoxide)=4∶1 and stirring for 12 h.After filtration through a 0.22 μm filter,the perovskite precursor solution was spin-coated on the ITO/NiOx/SAM substrate at 1 000 r/min for 5 s and 3 000 r/min for 40 s,and chlorobenzene(180 μL)was dropped onto the film at the last 15 s of the whole spinning process.The as-casted film was then annealed at 110 ℃ for 15 min.Subsequently,[6,6]-phenyl-C61-butyric acid methyl ester(PCBM,20 mg/mL in chlorobenzene)was spin-coated on the perovskite film at 3 000 r/min.Then,2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP,0.5 mg/mL in isopropanol)was spin-coated on the PCBM film at 6 000 r/min and annealed at 80 ℃ for 10 min.Finally,a 100 nm Ag electrode was thermally evaporated onto the BCP layer under a vacuum of 2× 10-4 Pa to complete the device fabrication.[Results]To optimize the SAM/perovskite buried interface,DCP was introduced as an additive into the MeO-2PACz SAM molecules.Scanning electron microscope(SEM)and X-ray diffraction(XRD)measurements showed that the introduction of DCP could improve the film formation of perovskite films and enhance the crystallinity of the perovskite films.X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FT-IR)measurements indicated that DCP could interact with Pb2+in the perovskite and passivate the buried perovskite interface.Steady-state and time-resolved photoluminescence tests revealed that the incorporation of DCP could promote the charge carrier transport and reduce the charge carrier recombination.As a consequence,the introduction of the SAM additive optimized the contact between SAM and perovskite,ultimately boosting the power conversion efficiency(PCE)of inverted PSCs from 23.58％to 24.64％.Moreover,the incorporation of DCP also enhanced the device stability,maintaining 85％of its initial PCE after 1 000 h of storage in a N2 atmosphere.[Conclusion]This study introduced a small-molecule additive into the SAM to optimize the buried interface between the perovskite and the hole transport layer,which facilitated charge carrier extraction and enhanced the photovoltaic performance and stability of PSCs.The strategy provides valuable insights for the fabrication of solution-processed,high-performance PSCs.