Construction of Efficient and Stable FAPbI₃ Perovskite Solar Cells through Bifunctional Ionic Liquid‐Assisted Crystallization and Defect Passivation

Abstract

FAPbI3 is considered one of the most ideal perovskite materials to construct highly efficient perovskite solar cell (PSC), but the poor phase stability and film‐forming properties hinder further performance improvements. Herein, an ionic liquid 3‐(2‐amino‐2‐oxoethyl)‐1‐methyl‐1H‐imidazol‐3‐ium chloride (AOMCl) with multifunctional cations and Cl anion to assist crystallization, reduce defects, and stabilize α‐FAPbI3 is reported. Results show that the perovskite film's nonradiative recombination and phase transition are suppressed after AOMCl treatment. The PSCs with AOMCl treatment obtain a power conversion efficiency (PCE) up to 22.01% with negligible hysteresis. In addition, the large‐area (1 cm2) device achieves a PCE of 17.11%. The AOMCl‐treated unencapsulated device exhibits impressive stability, maintaining an initial efficiency of over 94% after 1600 h in air environment. This work provides a strategy for designing FAPbI3 additive ideally.

Double‐Side Passivation of Perovskite Solar Cells for High Performance and Stability

“…The double device maintains 86.4% of initial PCE even after 1860 h at the thermal stress of 60 °C, indicating its robust thermal stability, as shown in Figure 4c. [63][64][65] Additionally, maximum power point tracking (MPPT) results are consistent with the thermal stability test, where the double device exhibits endurance for 1030 h with 80.2% retention of the initial PCE at the given continuous light condition, as shown in Figure 4d. [52,66,67] Since the light stability of perovskite solar cells is more sensitive than that of thermal stability, we have measured the light stability of top passivation.…”

Ion-Organic Compound Interface Strategy Enables High-Efficiency Perovskite Solar Cells

“…According to the reduced characteristic peak at 16.15°of the δ-FA phase perovskite in Figure 3e, TBAPF 6 can inhibit the transition from the α-FAPbI 3 phase to δ-FAPbI 3 phase. 34 We also evaluated XRD patterns of the perovskite with and without TBAPF 6 after 5 and 10 days of storage (Figure S7). A characteristic peak at 16.15°of the δ-FA phase perovskite occurred in the control perovskite, while it can be ignored in the TBAPF 6 -treated perovskite, demonstrating that TBAPF 6 can stabilize α-FAPbI 3 .…”

“…It is conducive to exciton dissociation and charge transport at the perovskite/Spiro-OMeTAD interface. According to the reduced characteristic peak at 16.15° of the δ-FA phase perovskite in Figure e, TBAPF 6 can inhibit the transition from the α-FAPbI 3 phase to δ-FAPbI 3 phase . We also evaluated XRD patterns of the perovskite with and without TBAPF 6 after 5 and 10 days of storage (Figure S7).…”

Role of Ionic Liquids in Perovskite Solar Cells

“…In addition to those mentioned above, many other functional groups have been introduced into ILs to improve the efficiency and stability of PSCs (Table 1), such as benzal groups (-CH 2 C 6 H 5 ), [7,36] vinyl groups (-CH=CH 2 ), [7,33,36] amide groups (-CONH 2 ), [37] and carboxyl groups (-COOH). [8,[11][12][13]15,19,38] In conclusion, to design an effective IL, first, an electron-rich chemical structure is necessary, such as imidazole rings, pyridine rings, and pyrrolidine rings, which can provide electrons to neutralize trap states.…”