PbI2 Films Research Articles

Electric-field-induced aging dynamics of triple-cation lead iodide perovskite at nanoscale

Herein, we report the nanoscale cations dynamics in Cs0.1MA0.15FA0.75PbI3 films during the electric-field-induced aging process using infrared scattering scanning near-field microscopy (IR s-SNOM) combined with a series of complementary analytical techniques such as PL-microscopy, SEM/EDX and ToF-SIMS. The revealed major field-induced aging pathways are related to the anodic oxidation of I− and the cathodic reduction of MA+ and FA+, which finally result in the depletion of organic species in the device channel and the formation of metallic lead. FA+ cations show significantly higher stability with respect to electrochemical reduction as compared to MA+ cations. Formamidinium cations are preserved on the surface of the near-cathode film area even after 40 days of the 1 V/μm field exposure, while MA+ cations demonstrate complete decomposition after 24 days. The obtained results demonstrate that IR s-SNOM represents a powerful technique for studying the spatially resolved field-induced degradation dynamics of hybrid perovskite absorbers and the identification of more promising materials resistant to the electric field.

Rubidium Halide Additive Engineering for Efficient and Stable Bifacial Perovskite Solar Cells

AbstractBifacial perovskite solar cells (PSCs) possess a dual light‐absorbing structure, which enables higher power output at lower additional costs. However, the replacement of metal electrodes with transparent ones leads to serious light loss, necessitating a thicker perovskite layer to compensate for this drawback. In this study, the impact of different rubidium halide (RbCl, RbBr, and RbI) additives is systematically investigated on precursor solubility and the quality of micron‐sized perovskite thick films prepared using a two‐step method. It is observed that RbCl exhibited the strongest interactions with PbI2, enhancing its solubility and leading to the formation of multihole PbI2 films that promote subsequent crystallization of thick perovskite film. Additionally, the RbCl‐based perovskite film demonstrates a narrowed bandgap attributed to the formation of a‐FAPbI3. Consequently, the short‐circuit current density (Jsc) and open‐circuit voltage (Voc) in the RbCl‐based bifacial PSCs are simultaneously enhanced, and a record efficiency of 20.86% (21.04% certified) is also obtained among n‐i‐p bifacial PSCs, exhibiting an ≈80% bifaciality and a power generation density (PGD) exceeding 24 mW cm−2 with a reflectivity value of 0.2. More importantly, the optimized device does not show any performance degradation after continuous illumination under 1sun for 1000 h.

Lead iodide secondary growth and π-π stack regulation for sequential perovskite solar cells with 23.62% efficiency

The sequential deposited perovskite solar cells (PSCs) have received widespread attention due to its application potential in large-scale perovskite module and perovskite/silicon tandem solar cells. However, insufficient reaction between organic ammonium salts and PbI2 leads to residual PbI2 and low crystallinity of perovskite films, and the fragile Pb-I bonds easily creates iodine loss and reduces the stability of PbI6 framework. In this work, the 4-fluorobenzylamine (FBA) with C = O and –NH2 is employed in PbI2 precursor solution to regulate the secondary growth process of PbI2 film. Due to the low Gibbs free energy and high crystallinity of porous PbI2 film, sufficient reaction between organic ammonium salts and PbI2 is promoted, which results in large-grain, low-defect perovskite films. At the same time, through hydrogen bonding and π-π stacking interactions, the stability of the PbI6 skeleton is effectively improved, significantly suppressing non-radiative recombination and reducing defect state density. Finally, this strategy increases the power conversion efficiency (PCE) of PSCs from 22.06 % to 23.62 %, and the target PSCs maintain 96 % of their initial PCE after being placed in nitrogen for 1300 h.

Self-Sacrificed Additive in Preparing PbI2 Film Enables the Oriented Growth of Perovskite Crystals for Improved Solar Cell Performance.

Due to the limitation of the diffusion kinetics of organic amine salts on the PbI2 layer in the two-step method, prepared perovskite particles are small in size, have many defects, and are randomly oriented, and the cell efficiency and stability are difficult to guarantee due to PbI2 residues. Here, we added a volatile additive, N,N,N',N'-tetramethylethylenediamine (TMEDA), to the PbI2 precursor solution and formed preaggregated atomic clusters with PbI2 through TMEDA, which reduced the Gibbs free energy of nucleation to obtain a porous PbI2 layer, and finally obtained a perovskite film with large particles, few defects, ideal crystal plane orientation, and no additive residues. The results show that the photoelectric conversion efficiency of the optimized device is increased by 1.68% (from 21.68% to 23.36%), and the unpackaged optimized device still maintains the maximum efficiency of 77% after being placed in the air for 1200 h. This study provides an effective way to fabricate efficient and stable perovskite solar cells by promoting the nucleation-induced crystallization orientation by volatile additives.

Colloidal Stabilizer‐Mediated Crystal Growth Regulation and Defect Healing for High‐Quality Perovskite Solar Cells

AbstractHigh‐quality perovskite (PVK) films is essential for the fabrication of efficient and stable perovskite solar cells (PSCs). However, unstable colloidal particles in PVK suspensions often hinder the formation of crystalline films with low defect densities. Herein, ethylenediaminetetraacetic acid (EDTA) as a colloidal stabilizer into lead iodide (PbI2) is introduced colloidal solutions. EDTA forms chelated complexes with Pb2+, enhancing the electrostatic repulsion and steric hindrance between colloidal particles. This stabilizes the particles and inhibits disordered motion (Brownian motion) and excessive aggregation. As a result, PbI2 films with a uniform hole distribution are formed, providing ample pathways for subsequent PVK film growth and sufficient space. During the film formation process, the replacement of molecules by formamidinium iodide (FAI) and EDTA slows down crystallization, ultimately leading to PVK films with large grain sizes and low defect density. By using this approach, champion power conversion efficiencies (PCEs) of 24.05% for FA0.97Cs0.03PbI3 PSC, 11.08% for CsPbBr3 PSC, and 25.19% for FA0.945MA0.025Cs0.03Pb(I0.975Br0.025)3 PSC are achieved. Moreover, the EDTA‐based FA0.97Cs0.03PbI3 device retains over 90% of its initial PCE after 1000 h at the maximum power point (MPP) under continuous illumination.

High performance and stability of perovskite solar cells achieved through anti-solvent modulation of multi-orientation PbI2 and stress relief

The morphology of the pre-deposited PbI2 layer plays a crucial role in determining the quality of perovskite films in sequentially deposited perovskite solar cells. The main reason is that the PbI2 film is too dense, which makes it difficult for organic salts to fully enter and react with them. This work presents a novel solvent extraction post-treatment method for the construction of bilayer PbI2 films. The PCE of the prepared champion device reaches 23.8 %, which is higher than 21.6 % of the control device. We observed that the perovskite solar cells treated with EA retained over 90 % of their initial efficiency after being stored for approximately 700 h in a nitrogen atmosphere, and over 80 % in air, demonstrating superior stability compared to the control group.

On the Vegard’s law compliance for CsxFA(1-x)PbI3 perovskite thin films

Perovskite-based solar cells (PSCs) have demonstrated remarkable high power conversion efficiency in recent years. However, the use of mono-organic cations (such as Methylammonium or Formamidinium) limits the potential for large-scale development due to potential degradation under environmental conditions. The incorporation of multi-cations has emerged as a strategy to enhance both performance and stability. The cesium (Cs) cation represents a solid alternative for partial substitution of Formamidinium. However, the initial concentration of precursors in the solution is often reported without establishing the final concentration of the cation present in the thin films. Herein, the incorporation of Cs cations into the FAPbI3 structure to produce a CsxFA(1-x)PbI3 perovskite with different values of x using a one-step spin coating process is demonstrated. Assessing the structural and optical properties, it is demonstrated that CsxFA(1-x)PbI3 films behave according to Vegard’s law for values of x between 0 and 0.66. In particular, CsxFA(1-x)PbI3, with an x concentration of 0.33 exhibits a cubic lattice parameter of 6.28 Å, lower than that for FAPbI3 but higher than that for CsPbI3. This concentration showed stability of the dark phase under ambient conditions for extended periods. In addition, this material has a bandgap of 1.5 eV, making it suitable for use in solar cells.

Controlling Water for Enhanced Homogeneities in Perovskite Solar Cells with Remarkable Reproducibility

AbstractTwo‐step sequential deposition of perovskite films is proven efficient and compatible with large‐scale production. Nevertheless, its critically regulated environmental humidity often remains a burden, hindering its applications in reproducible fabrication of perovskite solar cells (PSCs). Herein, by introducing a water ethyl acetate (W‐EA) solution treatment before annealing, improved perovskite crystallinity and homogeneity in FA0.95‐xMAxCs0.05PbI3 films without additional composition regulation is achieved. In situ Grazing‐incidence Wide‐angle X‐ray Scattering experiments highlighted accelerated crystallization kinetics in W‐EA‐treated films, leading to high‐quality perovskite formation. PSCs based on this method reached an optimal power conversion efficiency of 25.01% and demonstrated enhanced moisture resistance, retaining 88% efficiency after 1000 h in ambient conditions. This W‐EA treatment simplifies the fabrication process, greatly reducing the need for controlled humidity, and offers insights into the role of water in perovskite film crystallization, with significant implications to produce high‐performance PSCs.

Two-step preparation of methylammonium lead triiodide perovskite film via electrospray deposition of methylammonium iodide solution for solar cell applications

Solution-processable perovskite solar cells (PSCs) have the potential to revolutionize solar cell technology by enabling low power generation costs via low-cost device fabrication. However, most existing research regarding PSCs relies on the spin-coating method, which is not conducive to large-area film deposition. Therefore, the development of an alternative deposition method for perovskite films has become increasingly important for commercialization, for which electrospray deposition is a promising technique. This study investigates the two-step preparation of methylammonium lead triiodide (MAPbI3) perovskite films via the electrospray deposition of a methylammonium iodide (MAI) solution on a spin-coated PbI2 film. The gradual conversion of PbI2 to MAPbI3 with increasing MAI deposition time was revealed, accompanied by an increase in the size of the perovskite crystals. In addition, PSCs were successfully fabricated by electrospraying MAI, achieving a considerable power conversion efficiency of 7.86 % at the optimal MAI deposition time.

Quantifying Organic Cation Ratios in Metal Halide Perovskites: Insights from X-ray Photoelectron Spectroscopy and Nuclear Magnetic Resonance Spectroscopy.

The employment of metal halide perovskites (MHPs) in various optoelectronic applications requires the preparation of thin films whose composition plays a crucial role. Yet, the composition of the MHP films is rarely reported in the literature, partly because quantifying the actual organic cation composition cannot be done with conventional characterization methods. For MHPs, NMR has gained popularity, but for films, tedious processes like scratching several films are needed. Here, we use mechanochemical synthesis of MA1-x FA x PbI3 powders with various MA+: FA+ ratios and combine solid-state NMR spectroscopy (ssNMR) and X-ray photoelectron spectroscopy (XPS) to provide a reference characterization protocol for the organic cations' quantification in either powder form or films. Following this, we demonstrate that organic cation ratio quantification on thin films with ssNMR can be done without scraping the film and using significantly less mass than typically needed, that is, employing a single ∼800 nm-thick MA1-x FA x PbI3 film deposited by pulsed laser deposition (PLD) onto a 1 × 1 in.2, 0.2 mm-thick quartz substrate. While background signals from the quartz substrate appear in the 1H ssNMR spectra, the MA+ and FA+ signals are easily distinguishable and can be quantified. This study highlights the importance of calibrating and quantifying the source and the thin film organic cation ratio, as key for future optimization and scalability of physical vapor deposition processes.

Formation and degradation mechanism of methylammonium lead iodide perovskite thin film fabricated by electrospray technique

Electrospray deposition technique has been reported previously for fabricating effective and stable perovskite thin film, leading to efficient perovskite solar cells. In this work, a comprehensive investigation of the formation mechanism of methylammonium lead iodide perovskite (CH3NH3PbI3) film by electrospray technique is demonstrated and compared to the formation mechanism through the conventional spin coating technique. In the electrospray process, charged MAI nanoparticles are gradually introduced onto the PbI2 film, intercalating within the PbI2 structure to produce the perovskite film. In contrast, the spin-coating method involves supplying the MAI solution in bulk, leading to perovskite crystal formation through the dissolution of the PbI2 layer by the MAI solution, followed by recrystallization into perovskite oriented in the [110] direction, 30° inclined to the substrate. The impact of charge and the electric field on the formation of perovskite film using the electrospray is explored.Furthermore, the intrinsic stability of perovskite films is monitored in real-time in a highly humid environment (≥80 % relative humidity (RH)) using in-situ Grazing Incidence Wide Angle X-ray Scattering (GIWAXS), and a degradation mechanism is proposed to enhance the durability of the perovskite-based devices. The study further delves into the comparison of the stability of electrosprayed and spin-coated perovskite film, and the impact of humidity level and the presence of a hole-transporting layer on the stability of the perovskite layer. Overall, this work provides a detailed understanding of the formation and humidity-induced degradation mechanism of electrosprayed perovskite films, offering insights that can extend to various applications of perovskite materials.

Guanidine carbonate modified TiO2/Perovskite interface for efficient and stable planar perovskite solar cells

The rational design and modification of the buried interface are essential and challenging for high-performance perovskite solar cells (PSCs). TiO2 is a simple and readily available electron transport layer material, but its surface defects and poor interfacial contact with perovskite layers hinder its widespread application. Here, we propose an effective TiO2/perovskite interface modification strategy by introducing simple guanidine carbonate (GuaCO3) onto the surface of TiO2. Guanidine carbonate can improve the interfacial contact between TiO2 and perovskite, reduce non-radiative recombination, and enhance carrier extraction. Moreover, the PbI2 film grown on the TiO2/GuaCO3 substrate tended to become porous during the preparation of perovskite films by the traditional two-step method, which facilitated the complete reaction of organic ammonium salts with PbI2 and promoted the growth of high-quality perovskite films. The experimental results indicate that GuaCO3 can passivate the interfacial defects of TiO2/perovskite, as well as reduce the accumulation of interfacial charges. The device modified with GuaCO3 achieved a power conversion efficiency (PCE) of 23.39 %, which is significantly higher than that of the control device (21.73 %). After storage in an ambient environment at room temperature for 600 h, the unencapsulated device modified with GuaCO3 retained 78 % of its initial efficiency, while the control device retained only 57 % of its initial efficiency. These results indicate that interfacial modification with GuaCO3 is an effective strategy for improving the performance of PSCs.

Performance Improvement of Formamidinium‐Based Perovskite Photodetector by Solution‐Processed C8‐BTBT Modification

AbstractOrganic–inorganic hybrid perovskite has attracted extensive research due to its excellent optoelectronic properties and is a competitive candidate material for a new generation of photodetectors. However, lateral structure photodetectors based only on perovskite active materials still present moderate performance and poor stability. Herein, lateral structure formamidinium‐based perovskite FA0.9Cs0.1PbI3 photodetectors are reported which are modified by a solution‐processed organic semiconductor 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) layer for improved photosensitive performance and ambient/flexibility stability. High‐mobility organic semiconductor C8‐BTBT serves as an efficient hole transport layer that fills the grain boundaries and gaps of the FA0.9Cs0.1PbI3 film, enabling rapid extraction and transport of the photo‐generated carriers from the perovskite to the electrodes, resulting in enhanced photosensitive performance of the photodetector. Compared with the original device, the C8‐BTBT‐modified photodetector exhibits dramatically improved performance with a best responsivity of 1278 mA W−1, specific detectivity of 1.58 × 1012 Jones, external quantum efficiency of 298%, and fall time of 14.09 ms, which is 10.84 times less than 152.76 ms of the pure perovskite device. Moreover, the C8‐BTBT film acts as a protective layer for the FA0.9Cs0.1PbI3 film because of its good air stability and effective coverage, which significantly improves the ambient stability of the perovskite photodetector compared with the original device, increasing photocurrent retention from 2.5% to 61.5% or 81.5% at different humidity after 6 days. Furthermore, the C8‐BTBT‐modified perovskite photodetector exhibits outstanding flexibility performance, with only a 5% reduction in photocurrent under bending and almost no change after 200 bending cycles, while those of the pristine perovskite device have degraded to ≈80% and ≈75% under the same conditions, respectively. This study provides a facile and effective solution‐processed‐based strategy for constructing high‐performance and stable perovskite photodetectors.

Two-Step Perovskite Solar Cells with > 25% Efficiency: Unveiling the Hidden Bottom Surface of Perovskite Layer.

While significant efforts in surface engineering have been devoted to the conversion process of lead iodide (PbI2) into perovskite and top surface engineering of perovskite layer with remarkable progress, the exploration of residual PbI2 clusters and the hidden bottom surface on perovskite layer have been limited. In this work, a new strategy involving 1-butyl-3-methylimidazolium acetate (BMIMAc) ionic liquid (IL) additives is developed and it is found that both the cations and the anions in ILs can interact with the perovskite components, thereby regulating the crystallization process and diminishing the residue PbI2 clusters as well as filling vacancies. The introduction of BMIMAc ILs induces the formation of a uniform porous PbI2 film, facilitating better penetration of the second-step organic salt and fostering a more extensive interaction between PbI2 and the organic salt. Surprisingly, the oversized residual PbI2 clusters at the bottom surface of the perovskite layer completely diminish. In addition, advanced depth analysis techniques including depth-resolved grazing-incidence wide-angle X-ray scattering (GIWAXS) and bottom thinning technology are employed for a comprehensive understanding of the reduction in residual PbI2. Leveraging effective PbI2 management and regulation of the perovskite crystallization process, the champion devices achieve a power conversion efficiency (PCE) of 25.06% with long-term stability.

Enhancing Organic–Inorganic Perovskite Thin Film Crystallization via Vapor–Solid Reaction by Modifying PbI2 Precursors Films with Pyridinium Trifluoromethanesulfonate

The vapor–solid reaction technique holds potential for producing large‐scale organic–inorganic perovskite films, using a two‐step deposition process. The sucess of perovskite formation heavily relies on the crystallization of lead iodide (PbI2) precursor films. However, the high crystallinity of PbI2 can hinder organic vapors' diffusion and negatively affecting the solar cells by increasing charge recombination and accelerating degradation. To address this, pyridinium trifluoromethanesulfonate (PTFS) is introduced into the PbI2 precursor solution to control the nucleation and growth of PbI2 films. PTFS has been found to effectively suppresses PbI2 crystallization and enhance the integration of formamidinium ion (FA+) through hydrogen bonding, facilitating the full transformation of PbI2 into perovskite. It also minimizes defect formation by interacting with uncoordinated Pb2+ and FA+ ions. These modifications have significantly enhanced power conversion efficiency (PCE), reaching up to 21.19%, and the devices have maintained 93% of their initial performance after 1580 h of exposure to air.

In Situ Study of Purified Phase Transition Path for α‐FAPbI3 Crystallization

AbstractPhase transition during annealing in the two‐step sequential deposition has drawn intensive attention as its significance in fabricating superior perovskite films. However, previous works have not paid enough attention to the importance of the purified phase transition path in the crystallization process. Herein, different from the mixed paths in the conventional cognition, purified phase transition path for α‐FAPbI3 crystallization is achieved by introducing dimethylurea (DMU) into lead iodide (PbI2) precursor solution. The multifunctional molecule is found to design a penetrable porous PbI2 film and fundamentally regulate the perovskite crystallization by forming single phase transition path via the complete δ‐phase during annealing of perovskite. The role of DMU in purified transition path for α‐FAPbI3 crystallization is unraveled with in situ photoluminescence and grazing incidence wide‐angle x‐ray scattering (GIWAXS) investigation. The crystal quality of perovskite films is significantly improved, resulting in single crystal‐like film. The best‐performing perovskite solar cells (PSCs) deliver a power conversion efficiency of 24.75%, resulting from the higher FF of 83.25% and an improved long‐term stability up to 3600 h. This work highlights the importance of purified phase transition path for the superior crystal quality toward high‐performance perovskite photovoltaics.

Static anti-solvent treatment on lead iodide in two-step deposition of methylammonium lead iodide perovskite thin films

Static anti-solvent treatment is rarely employed for perovskite thin film fabrication, even though this method is dependent only on fewer thin film growth parameters as compared to the dynamic anti-solvent application. Thus, studies on the influence of static anti-solvent treatment on the properties of perovskite thin films is important to gain insight to the growth processes, which is very scarce as well. In this study, we investigate the static anti-solvent treatment to tailor the morphology of Lead Iodide (PbI2) thin films for the fabrication of precursor-free Methylammonium Lead Iodide (MAPI) perovskite thin films through the two-step deposition method using Chlorobenzene as an anti-solvent. Remarkable influence of the anti-solvent loading time on the film morphology of PbI2 and MAPI thin films is observed. The crystallinity of PbI2 decreases upon increasing the anti-solvent loading time. A complete conversion of the precursors to MAPI along with the largest grain size are attained even at short loading times, ∼5s. Grain size does not increase considerably at higher loading times. Linear absorption studies on MAPI thin films show an increase in the Urbach energy with an increase in the loading time, which indicates an increase in the defect density. The increase in defect density with anti-solvent loading time is attributed to the concurrent decrease in the crystallinity of the PbI2 thin film. Steady-state and time-resolved photoluminescence (PL) studies performed on the MAPI thin films show highest PL intensity and life time at an optimum anti-solvent loading time (∼5s), which arises due to the trade off between largest grain size and lowest defect density. These observations not only highlights the need for an optimum crystallinity in the PbI2 thin films for the fabrication of superior quality MAPI thin films but also infers an optimum static anti-solvent loading time as the increase in grain size and life time enhances the device performance while an increase in defect density degrades the performance.

2D BA2PbI4 Regulating PbI2 Crystallization to Induce Perovskite Growth for Efficient Solar Cells.

Using seeds to control the crystallization of perovskite film is an effective strategy for achieving high-efficiency perovskite solar cells (PSCs). Owing to their excellent environmental stability brought by their long alkyl chain, n-butylammonium (BA) cations are widely used for fabricating efficient and stable PSCs. However, BA-based 2D perovskite is seldom been investigated as a seed. Here, BA2PbI4 is employed to regulate the crystallization of PbI2, acting as nucleation centers. As a result, porous PbI2 film with high crystallinity is obtained, which allows the realization of perovskite film with preferential crystal orientations of (001) and large grain size of over 2µm. The corresponding PSC achieves a high power conversion efficiency (PCE) of 24.30% and exhibits satisfactory stability, retaining 91.70% of the initial PCE after 300h of thermal aging at 85°C.

Co-evaporated oriented DMA1-xCsxPbI3 perovskite films for photovoltaics

Thermally evaporated cesium lead triiodide (CsPbI3) is a frontier research direction for perovskite-silicon tandem solar cells because of the matching bandgap and good conformality with textured silicon. However, the random orientation and small grains for the co-evaporated CsPbI3 thin films fabricated at low temperature, resulting in harmful defects and non-radiative recombination. Here, dimethylammonium iodide (DMAI) is introduced into the co-evaporation system at a substrate temperature of 50 °C to prepare preferentially oriented DMA0.06Cs0.94PbI3 film with less defects and enhanced humidity stability. The bandgap also can be reduced from 1.76 eV (γ-CsPbI3) to 1.73 eV. The p-i-n photovoltaic device based on this film achieves an efficiency of 16.10% with suppressed non-radiative recombination, rivaling with the thermally evaporated wide-bandgap CsPbI3 solar cells prepared at a high temperature (∼ 350 °C). This in-situ evaporated alloying strategy can pave the way for the crystallization and defect control during perovskite co-evaporation.

Covalent organic frameworks for modulating crystallization kinetics in perovskite photovoltaics

Covalent organic frameworks (COFs), recognized for their conjugated frameworks, adjustable porosity, and customizable functionalization, are emerging as versatile materials in perovskite photovoltaics with the potential to enhance both device performance and stability. However, a comprehensive understanding of their precise influence on the intricate phenomenon of perovskite crystallization kinetics is still lacking. In this study, we have successfully synthesized two distinctive COF materials, namely HIAM-0001 and HIAM-0004, utilizing the structural units of 5′,5″″-(benzo[c] [1,2,5]thiadiazole-4,7-diyl)bis(([1,1′:3′,1″-terphenyl]-4,4″-dicarbaldehyde)) (BT-TDA), with either the additional unit p-xylylenedicyanide (PDAN) or 2,2′-([2,2′-bipyridine]-5,5′-diyl) diacetonitrile (BPyDAN). By incorporating them into the PbI2 layer, we have facilitated high-quality perovskite film fabrication through a two-step process. The COF-assisted PbI2 films exhibited a distinct porous structure, facilitating organic salt solution permeation and reducing PbI2 residues. Notably, in-situ UV–vis absorption characterization revealed slowed perovskite film crystallization kinetics with COF assistance, leading to the formation of larger crystal grains, fewer grain boundaries, reduced defect density, and suppressed non-radiative recombination, ultimately resulting in improved device performance. In comparison to HIAM-0001, the enhanced π-π interactions of HIAM-0004, with its bipyridine-based unit, exhibited more pronounced interactions with the perovskite, contributing to a remarkable PCE of 24.06% and excellent device stability. This study underscores the pivotal role of COF modification in shaping perovskite film crystallization kinetics, thereby enhancing film quality, reducing defects, and boosting device stability.