Mediating the Local Oxygen-Bridge Interactions of Oxysalt/Perovskite Interface for Defect Passivation of Perovskite Photovoltaics

Abstract

Passivation, as a classical surface treatment technique, has been widely accepted in start-of-the-art perovskite solar cells (PSCs) that can effectively modulate the electronic and chemical property of defective perovskite surface. The discovery of inorganic passivation compounds, such as oxysalts, has largely advanced the efficiency and lifetime of PSCs on account of its favorable electrical property and remarkable inherent stability, but a lack of deep understanding of how its local configuration affects the passivation effectiveness is a huge impediment for future interfacial molecular engineering. Here, we demonstrate the central-atom-dependent-passivation of oxysalt on perovskite surface, in which the central atoms of oxyacid anions dominate the interfacial oxygen-bridge strength. We revealed that the balance of local interactions between the central atoms of oxyacid anions (e.g., N, C, S, P, Si) and the metal cations on perovskite surface (e.g., Pb) generally determines the bond formation at oxysalt/perovskite interface, which can be understood by the bond order conservation principle. Silicate with less electronegative Si central atoms provides strong O-Pb motif and improved passivation effect, delivering a champion efficiency of 17.26% for CsPbI2Br solar cells. Our strategy is also universally effective in improving the device performance of several commonly used perovskite compositions.

Stoichiometric Dissolution of Defective CsPbI2Br Surfaces for Inorganic Solar Cells with 17.5% Efficiency

“…PL measurements under continuous light irradiation were carried out to detect the light‐induced ion migration behavior of pristine and [BMIM]PF 6 films, which is closely related to device stability. [ 43 ] The redshift in the PL spectra indicates the formation of light‐induced low‐bandgap I‐rich domains that represent a trap for electrons and holes and induce PL quenching. [ 44 ] The peak position of the [BMIM]PF 6 film exhibited a slight redshift of 5 nm under steady light illumination for 30 min, while the pristine film shifted from 653 to 664 nm, which was approximately 2.2 times the shift of the [BMIM]PF 6 film ( Figure 5 A,B).…”

Effective Surface Passivation via Intermolecular Interactions for High‐Performance Perovskite Solar Cells

“…The rapid decay time of τ 1 and slow decay time of τ 2 are typically related to bimolecular recombination of photo‐generated free carriers and trap‐assisted recombination, respectively. [ 39 ] After the DHA treatment, both τ 1 and τ 2 of the perovskite films increased significantly. The average PL lifetime can be calculated according to the formula…”

Crosslinkable and Chelatable Organic Ligand Enables Interfaces and Grains Collaborative Passivation for Efficient and Stable Perovskite Solar Cells

“…Therefore, optimizing the SnO 2 /perovskite interface to suppress the formation of surface traps/defects is vital to boosting device performance. [ 26,27 ] Generally, further modification at the SnO 2 /perovskite interface is successfully employed to reduce defects and enhance conductivity, thereby achieving high‐performance PerSCs. [ 28,29 ]…”

“…Therefore, optimizing the SnO 2 /perovskite interface to suppress the formation of surface traps/defects is vital to boosting device performance. [26,27] Generally, further modificationThe organic-inorganic halide perovskite solar cell (PerSC) is the state-of-theart emerging photovoltaic technology. However, the environmental water/ moisture and temperature-induced intrinsic degradation and phase transition of perovskite greatly retard the commercialization process.…”

“…Therefore, optimizing the SnO 2 /perovskite interface to suppress the formation of surface traps/defects is vital to boosting device performance. [26,27] Generally, further modification…”