Robust Self‐Assembled Molecular Passivation for High‐Performance Perovskite Solar Cells

Abstract

Defect passivation via post‐treatment of perovskite films is an effective method to fabricate high‐performance perovskite solar cells (PSCs). However, the passivation durability is still an issue due to the weak and vulnerable bonding between passivating functional groups and perovskite defect sites. Here we propose a cholesterol derivative self‐assembly strategy to construct crosslinked and compact membranes throughout perovskite films. These supramolecular membranes act as a robust protection layer against harsh operational conditions while providing effective passivation of defects from surface toward inner grain boundaries. The resultant PSCs exhibit a power conversion efficiency of 23.34 % with an impressive open‐circuit voltage of 1.164 eV. The unencapsulated devices retain 92 % of their initial efficiencies after 1600 h of storage under ambient conditions, and remain almost unchanged after heating at 85 °C for 500 h in a nitrogen atmosphere, showing significantly improved stability.

4-Trifluorophenylammonium Iodide-Based Dual Interfacial Modification Engineering toward Improved Efficiency and Stability of SnO2-Based Perovskite Solar Cells

“…The determined trap-filling limit voltage ( V TFL ) value of the device with CF 3 PhAI treatment at dual contact interfaces decreased to 0.28 from 0.54 V of the pristine device without CF 3 PhAI treatment. Correspondingly, the trap density ( n t ) of the treated device was significantly reduced from 7.5 × 10 15 to 3.9 × 10 15 cm –3 (Table S3), confirming better charge extraction and transport, in good agreement with findings from the SSPL spectra shown in Figure S12. Detailed analysis and calculations of n t are provided in the Supporting Information.…”

Bifunctional Cellulose Interlayer Enabled Efficient Perovskite Solar Cells with Simultaneously Enhanced Efficiency and Stability

“…[32,33] All detailed synthetic procedures and methods can be found in the Supporting Information. The chemical structures of C-Cz were confirmed by the 1 H NMR and 13 C nuclear magnetic resonance (NMR) spectra (Figures S1-S3, Supporting Information). The degree of substitution (DS) of the carbazole unit in C-Cz was almost 1.0, as calculated from the integration values of the peaks corresponding to aromatic and cellulose ring protons in the 1 H NMR spectra.…”

“…The characteristic peaks of the Pb 4f and I 3d spectrum shift toward the higher binding energy after treating with C‐Cz (0.3 eV for Pb 4f and 0.2 eV for I 3d, respectively), supporting the strong electronic interaction between C‐Cz and Pb and I on the perovskite surface, and further suggesting that C‐Cz effectively passivates the perovskite surface. [ 13,16,56,57 ]…”

“…[17][18][19] Generally, organic small molecules and polymers with different functionalities can serve as effective modifiers for optimizing interfacial contact at perovskite grain boundaries or perovskite/hole-transporting material (HTM) interface. [13][14][15][20][21][22] Compared with small molecules, polymers are found to be beneficial for durable defect passivation under a moisture atmosphere owing to their long-chain molecular structure and abundant functional group sites. [15] For example, poly(vinyl acetate), [15] poly(ethylene glycol) diacrylate, [23] poly(methyl methacrylate), [24] poly(4vinylpyridine) [25] and hetero-cycle-based (thiophene, [20] quinoxaline, [14] benzothiadiazole [22] and bithiophene imide [26] ) conjugated polymers, have been reported as adequate interfacial layers for high-performance PSCs with good stability.…”

“…Specifically, the solution-processed polycrystalline perovskite films inevitably generate a high density of defects at the surface and grain boundaries, such as uncoordinated Pb 2+ and halide ionic defects. [12,13] These defects act as charge traps that can aggravate non-radiative recombination and ion migration, seriously affecting device efficiency and stability. [14][15][16] To overcome these issues, numerous strategies, such as additive engineering, compositional modulation and interfacial engineering, have been developed.…”