Regulating the electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of perovskite solar cells (PSCs) as well as suppress their hysteresis. Herein, the SnO2 ETL using a cost‐effective modification material rubidium fluoride (RbF) is modified in two methods: 1) adding RbF into SnO2 colloidal dispersion, F and Sn have a strong interaction, confirmed via X‐ray photoelectron spectra and density functional theory results, contributing to the improved electron mobility of SnO2; 2) depositing RbF at the SnO2/perovskite interface, Rb+ cations actively escape into the interstitial sites of the perovskite lattice to inhibit ions migration and reduce non‐radiative recombination, which dedicates to the improved open‐circuit voltage (Voc) for the PSCs with suppressed hysteresis. In addition, double‐sided passivated PSCs, RbF on the SnO2 surface, and p‐methoxyphenethylammonium iodide on the perovskite surface, produces an outstanding PCE of 23.38% with a Voc of 1.213 V, corresponding to an extremely small Voc deficit of 0.347 V.
Defect
passivation is an effective method to improve the performance
of perovskite solar cells. In this study, four phenethylammonium iodides
featuring different functional groups directly linking to the benzene
ring are introduced on the surface of perovskite films ((FAPbI3)1–x
(MAPbBr3–y
Cl
y
)
x
) to investigate their passivation effects. It is found that
the electron density of the benzene ring has significant influence
on the interfacial passivation: phenethylammonium iodide with electron-donating
groups (methoxyl and methyl) present favorable passivation effects,
while the salt with electron-withdrawing group (nitro) delivers undesirable
impacts. The passivation is attributed to the electrostatic interaction
between the benzene ring and the undercoordinated Pb2+ ions.
The salt-treated films are employed to fabricate solar cells, and
an efficiency of 22.98% is achieved. In addition, the treated device
shows good long-term stability for 1000 h of storage in a dark, ambient
environment.
Summary
An efficient electron transport layer (ETL) between the perovskite absorber and the cathode plays a crucial role in obtaining high-performance planar perovskite solar cells (PSCs). Here, we incorporate 2,2,2-trifluoroethanol (TFE) in the commonly used tin oxide (SnO
2
) ETL, and it successfully improves the power conversation efficiency (PCE) and suppresses the hysteresis of the PSCs: the PCE is increased from 19.17% to 20.92%, and the hysteresis is largely reduced to be almost negligible. The origin of the enhancement is due to the improved electron mobility and optimized work function of the ETL, together with the reduced traps in the perovskite film. In addition, O
2
plasma is employed to treat the surface of the TFE-incorporated SnO
2
film, and the PCE is further increased to 21.68%. The concept here of incorporating organic small molecules in the ETL provides a strategy for enhancing the performance of the planar PSCs.
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