Secondary Anti‐Solvent Treatment for Efficient 2D Dion–Jacobson Perovskite Solar Cells

Abstract

inherent instability of halide perovskite when it is exposed to the ambient environment, such as heat, [5] light, [6] and humidity, [7] becomes a major obstacle for its commercial applications. The 2D perovskites exhibit improved stability due to the introduction of hydrophobic bulky organic cations, [8,9] but the PCE of 2D PSCs is much lower than the 3D PSCs. [10] Enhanced crystallinity quality and reduced trap density are beneficial to improve the performance of 2D PSCs. It is noteworthy that the one-step spin coating anti-solvent method is universally used to fabricate high-efficiency 2D PSCs. [11] The anti-solvent can promote solvent extraction, tune the crystal nucleation, and form a uniform and high-quality films. [12,13] It has been proved that surface morphology, thickness, and grain size of the film are highly dependent on the anti-solvent including the type of anti-solvent, dripping time, and volume. [14] Through the development of an anti-solvent, researchers have made great efforts to improve the crystallization of perovskite films. [15,16] However, due to the ionic properties of perovskite lattice, onestep anti-solvent processed perovskite films will inevitably produce high-density defects. [17] Furthermore, the residual solvents Surface defects-mediated nonradiative recombination plays a critical role in the performance and stability of perovskite solar cells (PSCs) and surface post-treatment is widely used for efficient PSCs. However, the commonly used surface passivation strategies are one-off and the passivation defect ability is limited, which can only solve part of the defects in the topmost surface area. Here, a secondary anti-solvent strategy is proposed to further reduce surface defects based on conventional surface passivation for the first time. Based on this, the crystallization quality of 2D Dion-Jacobson perovskite is enhanced and the surface defects density is further reduced by nearly two orders. In addition, a gradient structure of perovskite with n = 2 phases located at the top of the film and 3D-like phases located at the bottom of the film can also be obtained. The modulated perovskite film boosts the efficiency of 2D pero v skites (n = 5) up to 19.55%. This strategy is also very useful in other anti-solvent processed perovskite dipping systems, which paves a promising avenue for minimizing surface defects toward highly efficient perovskite devices.

The rise of quasi-2D Dion–Jacobson perovskites for photovoltaics

“…Moreover, a secondary anti-solvent method was reported by Zhang and co-workers for further passivating surface defects. 105 Fig. 15f shows a schematic diagram of the common and secondary anti- solvent processes for (BDA)(MA 0.07 FA 0.93 ) 4 Pb 5 I 16 perovskite preparation.…”

Improved Performance and Stability of Quasi-Two-Dimensional Perovskite Solar Cells by Post-treatment with Acetaminophen

“…Despite better stability, the efficiencies of the quasi-2D PSCs are still lower than those of the 3D ones. To solve this issue, some methods have been adopted, such as additive engineering, hot casting, and post-treatment of the perovskite. − In these methods, post-treatment of the perovskite is an effective method to enhance the performance and stability of quasi-2D PSCs. Jin et al adopted a sequential post-treatment method to fabricate quasi-2D ACI-phase PSCs, where guanidinium thiocyanate (GASCN) and methylammonium chloride (MACl) were used as post-treatment reagents, leading to a high PCE of 15.27%.…”

“…To solve this issue, some methods have been adopted, such as additive engineering, hot casting, and post-treatment of the perovskite. − In these methods, post-treatment of the perovskite is an effective method to enhance the performance and stability of quasi-2D PSCs. Jin et al adopted a sequential post-treatment method to fabricate quasi-2D ACI-phase PSCs, where guanidinium thiocyanate (GASCN) and methylammonium chloride (MACl) were used as post-treatment reagents, leading to a high PCE of 15.27%. Zhang and Park applied post-treatment to quasi-2D ACI-phase PSCs, where amphoteric imidazolium iodide (ImI) was used as a post-treatment reagent; thus, a high efficiency over 22% was obtained.…”

Defect Regulation of Efficient Dion–Jacobson Quasi-2D Perovskite Solar Cells via a Polyaspartic Acid Interlayer

“…A secondary anti-solvent strategy for DJ quasi-2D perovskite films was proposed by Zhang et al The surface defect density was significantly reduced based on conventional surface passivation, which paved another route to further improve the efficiency of PSCs. 17 by Chen and co-workers, which could effectively improve defect passivation and charge transport. 18 However, the reported investigation on DJ quasi-2D PSCs mostly focuses on the surface modification of perovskite-active layers, while the study about the underlying surface (interface at the CTL/perovskite) is rarely reported.…”

“…The device with interfacial modification achieved an improved PCE from 13.78 to 16.75%, which was mainly attributed to the suppression of bulk and interfacial defects. A secondary anti-solvent strategy for DJ quasi-2D perovskite films was proposed by Zhang et al The surface defect density was significantly reduced based on conventional surface passivation, which paved another route to further improve the efficiency of PSCs . A modified interface at the DJ-phase perovskite/charge transporting layer (CTL) through a novel annealing process of perovskite films was demonstrated by Chen and co-workers, which could effectively improve defect passivation and charge transport …”