Intermediate Phase Engineering with 2,2‐Azodi(2‐Methylbutyronitrile) for Efficient and Stable Perovskite Solar Cells

Abstract

Sequential deposition has been widely employed to modulate the crystallization of perovskite solar cells because it can avoid the formation of nucleation centers and even initial crystallization in the precursor solution. However, challenges remain in overcoming the incomplete and random transformation of PbI2 films with organic ammonium salts. Herein, a unique intermediate phase engineering strategy has been developed by simultaneously introducing 2,2‐azodi(2‐methylbutyronitrile) (AMBN) to both PbI2 and ammonium salt solutions to regulate perovskite crystallization. AMBN not only coordinates with PbI2 to form a favorably mesoporous PbI2 film due to the coordination between Pb2+ and the cyano group (C≡N), but also suppresses the vigorous activity of FA+ ions by interacting with FAI, leading to the full PbI2 transformation with the preferred orientation. Therefore, perovskites with favorable facet orientations are obtained, and the defects are largely suppressed owing to the passivation of uncoordinated Pb2+ and FA+. As a result, a champion power conversion efficiency over 25% with a stabilized efficiency of 24.8% is achieved. Moreover, the device exhibits an improved operational stability, retaining 96% of initial power conversion efficiency under 1000 h continuous white‐light illumination with an intensity of 100 mW cm−2 at ≈55 °C in N2 atmosphere.

Synergistic Effect of 2-(Trifluoromethyl) Benzimidazole on the Stability and Performance of Perovskite Solar Cells

“…Furthermore, as shown in the Tauc plot (Figure d), the cut-off edges of the two curves overlap, indicating that TFMBI-modified has no effect on the perovskite bandgap ( E g = 1.55 eV). The Fermi energy level ( E F ) can be calculated using the cut-off edge in the UPS spectrum (Figure e) with the following equation: E F = −21.22 – E cut‑off (where E cut‑off represents the cut-off energy). The calculated results reveal that the pristine and TFMBI-modified perovskite films’ E F is −4.94 and −4.66 eV, respectively.…”

Dual‐Interface Engineering in Perovskite Solar Cells with 2D Carbides

“…The PbÀ Cl bonding can trigger an overall reaction of the PbI 2 film with organic amine salt, favoring the formation of α-FAPbI 3 . [46] Furthermore, thin films coated with NanoGDY can achieve a uniform surface morphology devoid of pinholes, with an increased crystal size of 2.56 mm (Supplementary Figure 15). In addition to the enhanced film morphology, the film's crystallinity significantly improved.…”

Dual‐Interface Engineering in Perovskite Solar Cells with 2D Carbides

“…The PbÀ Cl bonding can trigger an overall reaction of the PbI 2 film with organic amine salt, favoring the formation of α-FAPbI 3 . [46] Furthermore, thin films coated with NanoGDY can achieve Angewandte Chemie a uniform surface morphology devoid of pinholes, with an increased crystal size of 2.56 mm (Supplementary Figure 15). In addition to the enhanced film morphology, the film's crystallinity significantly improved.…”

“…Notably, the MPG film is more conducive to hole extraction due to the narrow offset (DE h ) of the MPG perovskite film (0.23 eV) compared to the DE h of the control film (0.36 eV). [46] The large DE h would diminish interfacial concentration and the open-circuit voltage due to the harmful hole transfer rate brought by thermionic loss. [50] Consequently, the MPG film assures a smoother carrier transport from the perovskite layer to the HTL.…”