Rapid Nucleation and Slow Crystal Growth of CsPbI₃Films Aided by Solvent Molecular Sieve for Perovskite Photovoltaics

Abstract

The main reason for large energy loss in all‐inorganic perovskites is ascribed to the slow nucleation and fast crystallization of all‐inorganic perovskite films. Herein, a manipulating strategy is demonstrated to simultaneously realize rapid nucleation and slow crystal growth of CsPbI3 perovskite films by employing solvent molecular sieves in the antisolvent. First, the antisolvent treatment of mixed chlorobenzene and ethyl alcohol can induce the instantaneous supersaturation of perovskites to achieve rapid nucleation. Subsequently, the molecular layer of phthalimide (2‐N) molecules on the perovskite surface can be used as solvent molecular sieves to precisely control the evaporation of the solvent through molecule–solvent interactions. In addition, the molecules remaining on the surface can also effectively passivate the surface defects and improve the device performance. By this strategy, a synchronous regulation of rapid nucleation and slow crystal growth of perovskite films is realized for the first time. As a result, the CsPbI3 film with 2‐N treatment presents high‐quality crystallinity with large grains and less defects. The champion device exhibits an outdoor power conversion efficiency (PCE) up to 20.14% under AM1.5G illumination, and an indoor PCE up to 40.07% (Pout:133.9 µW cm–2) under a commonly used light‐emitting diode light source (2956 K, 1062 lux).

Long-chain anionic surfactants enabling stable perovskite/silicon tandems with greatly suppressed stress corrosion

“…18 ) 40 . The nonpolar monolayer of long-alkyl-chain backbones, which is spontaneously self-limited on the solution surface as mentioned above, plays a “solvent molecular sieve” role in alleviating the evaporation of polar solvent 41 . The SO 4 2− , as a strong kosmotropic ion, can foster the strongly H-bonded network in polar solvent molecules, also slowing down the evaporation 42 .…”

Cs4PbI6-Cl Nucleation Seeds Assisted Highly-Oriented Inorganic CsPbI3 Perovskites for Efficient Perovskite Solar Cells

“…To fundamentally understand the role of DMACl during the crystallization of the CsPbI 3 perovskite films, the different precursor solutions without and with DMACl additives were further explored, which is because the nucleation of the perovskites might occur during the process of spin-coating and solvent volatilization. 18 When the ratio of DMACl exceeded 5% (2.85 mg/mL) in the precursor solution, the solution became cloudy (Figure S8), which suggests that there are low solubility complexes formed in the precursor. 24 Since Cs 4 PbI 6 and DMAPbI 3 are formed in precursor solutions as intermediates, 33 the low solubility complexes might be one of the intermediates combined with Cl − .…”

“…Therefore, compared to the PSCs based on the hybrid perovskites with similar bandgap energy, CsPbI 3 -PSCs still show relatively lower photovoltaic performance owing to the poor crystallization of CsPbI 3 perovskite films . The additive engineering of perovskite precursor solutions has become one of the most promising strategies to improve the crystal quality and suppress defects of the CsPbI 3 perovskite films by forming intermediate complexes during the crystallization of the perovskite films. − Yang et al found that the Cl – ions would benefit the nucleation of the perovskites without entering into the perovskite lattice, leading to perovskites with improved optoelectronic properties being obtained . Therefore, organic chloride additives, such as methylammonium chloride (MACl) and formamidinium chloride (FACl), were applied in the perovskite precursor solutions to form the intermediate species and regulate the crystallization of perovskite films. , Wang et al fabricated high crystalline uniaxial-orientated perovskite films with enhanced charge-carrier transport by adding amino-functionalized carbon nanotubes and MACl .…”

Low‐Dimensional Phase Regulation to Restrain Non‐Radiative Recombination for Sky‐Blue Perovskite LEDs with EQE Exceeding 15 %

“…The trap density of the target perovskite films, especially in the shallow energy level region (0.31-0.39 eV), is significantly reduced, which is connected to shallow-level traps on the surface of perovskite film. [27,28] The trap density was assessed by the drive-level capacitance profiling (DLCP) to see the spatial distribution of trap density throughout the device profile, [29,30] as shown in Figure S9. Evidently, DFBP treatment greatly drained the trap density across the profiling distance in the whole perovskite film.…”