JIALINGBO

A vapor deposition method in combination with a solvent-assisted recrystallization technique is presented to fabricate high-quality larger-area perovskite film. Efficiency of 19.9% is achieved, which is among the highest values ever reported for minimodules based on vapor-deposited perovskite.

Abstract

Vapor deposition is a promising technology for the mass production of perovskite solar cells. However, the efficiencies of solar cells and modules based on vapor-deposited perovskites are significantly lower than those fabricated using the solution method. Emerging evidence suggests that large defects are generated during vapor deposition owing to a specific top-down crystallization mechanism. Herein, a hybrid vapor deposition method combined with solvent-assisted recrystallization for fabricating high-quality large-area perovskite films with low defect densities is presented. It is demonstrated that an intermediate phase can be formed at the grain boundaries, which induces the secondary growth of small grains into large ones. Consequently, perovskite films with substantially reduced grain boundaries and defect densities are fabricated. Results of temperature-dependent charge-carrier dynamics show that the proposed method successfully suppresses all recombination reactions. Champion efficiencies of 21.9% for small-area (0.16 cm²) cells and 19.9% for large-area (10.0 cm²) solar modules under AM 1.5 G irradiation are achieved. Moreover, the modules exhibit high operational stability, i.e., they retain >92% of their initial efficiencies after 200 h of continuous operation.

Advanced Energy Materials, Volume 13, Issue 27, July 21, 2023.

Ytterbium fluoride (YbF₃) is introduced as a multifunctional additive for perovskite precursor solution. The addition of YbF₃ improved the quality, passivated the defects, and improved the stability of perovskite film. At the same time, the power conversion efficiency (PCE) of perovskite solar cell is also improved. By using YbF₃ as additive, the device is prepared with a champion PCE of 24.53%.

Abstract

With better light utilization, larger tolerance factor, and higher power conversion efficiency (PCE), the HC(NH₂)₂ ⁺(FA)-based perovskite is proven superior to the popular CH₃NH₃ ⁺ (MA)- and Cs-based halide perovskites in solar cell applications. Unfortunately, limited by intrinsic defects within the FA-based perovskite films, the perovskite films can be easily transformed into a yellow δ-phase at room temperature in the fabrication process, a troublesome challenge for its further development. Here, ytterbium fluoride (YbF₃) is introduced into the perovskite precursor for three objectives. First of all, the partial substitution of Yb³⁺ for Pb²⁺ in the perovskite lattice increases the tolerance factor of the perovskite lattice and facilitates the formation of the α phase. Second, YbF₃ and DMSO in the solvent form a Lewis acid complex YbF₃·DMSO, which can passivate the perovskite film, reduce defects, and improve device stability. Consequently, the YbF₃ modified Perovskite solar cell exhibits a champion conversion efficiency of 24.53% and still maintains 90% of its initial efficiency after 60 days of air exposure under 30% relative humidity.

Four novel efficient dumbbell-shaped PAH-BODIPY-triarylamine hybrid systems are designed as hole-transporting materials for planar inverted perovskite solar cells. The molecules are resistant to UVC 254 nm germicidal light and thermally stable until 350 °C. Their devices exhibit outstanding PCE of 20.26% (TM-02) and 16.98 to 18.80% (other compounds). This highlights the potential of PAH-BODIPY-triarylamine derivatives for next-generation photovoltaics.

Abstract

Dumbbell-shaped systems based on PAHs-BODIPY-triarylamine hybrids TM-(01-04) are designed as novel and highly efficient hole-transporting materials for usage in planar inverted perovskite solar cells. BODIPY is employed as a bridge between the PAH units, and the effects of the conjugated π-system's covalent attachment and size are investigated. Fluorescence quenching, 3D fluorescence heat maps, and theoretical studies support energy transfer within the moieties. The systems are extremely resistant to UVC 254 nm germicidal light sources and present remarkable thermal stability at degradation temperatures exceeding 350 °C. Integrating these systems into perovskite solar cells results in outstanding power conversion efficiency (PCE), with TM-02-based devices exhibiting a PCE of 20.26%. The devices base on TM-01, TM-03, and TM-04 achieve PCE values of 16.98%, 17.58%, and 18.80%, respectively. The long-term stability of these devices is measured for 600 h, with initial efficiency retention between 94% and 86%. The TM-04-based device presents noticeable stability of 94%, better than the reference polymer PTAA with 91%. These findings highlight the exciting potential of dumbbell-shaped systems based on PAHs-BODIPY-triarylamine derivatives for next-generation photovoltaics.

Herein, a 4-amino-2,3,5,6-tetrafluorobenzoate cesium (ATFC) is developed as a bifacial defect passivator to tailor the perovskite/TiO₂ interface. The comprehensive experiments confirm that ATFC can passivate multiple defects, improve electrical properties, optimize energy band structure of TiO₂ layer, and synergistically passivate Pb-related defects at perovskite buried surface. Consequently, ATFC-modified γ-CsPbI₃ device achieves a remarkable efficiency of 21.11% and improved operational stability.

Abstract

The poor interface quality between cesium lead triiodide (CsPbI₃) perovskite and the electron transport layer limits the stability and efficiency of CsPbI₃ perovskite solar cells (PSCs). Herein, a 4-amino-2,3,5,6-tetrafluorobenzoate cesium (ATFC) is designed as a bifacial defect passivator to tailor the perovskite/TiO₂ interface. The comprehensive experiments demonstrate that ATFC can not only optimize the conductivity, electron mobility, and energy band structure of the TiO₂ layer by passivation of the undercoordinated Ti⁴⁺, oxygen vacancy (V _O), and free OH defects but also promote the yield of high-quality CsPbI₃ film by synergistic passivation of undercoordinated Pb²⁺ defects with the CO group and F atom, and limiting I⁻ migration via F···I interaction. Benefiting from the above interactions, the ATFC-modified CsPbI₃ device yields a champion power conversion efficiency (PCE) of 21.11% and an excellent open-circuit voltage (V _OC) of 1.24 V. Meanwhile, the optimized CsPbI₃ PSC maintains 92.74% of its initial efficiency after aging 800 h in air atmosphere, and has almost no efficiency attenuation after tracking at maximum power point for 350 h.

2,6-bis(4-(bis(4-methoxyphenyl)amino)phenyl)pyrrolo[3,4-f]isoindole-1,3,5,7(2 H,6 H)-tetraone (Pyr-TPA), with superior defect passivation effect for perovskite and decent carrier transport properties, as well as ideal solubility, is developed.

Interfacial passivation is a crucial technique for improving the performance of perovskite solar cells (PSCs) by suppressing nonradiative recombination. Incorporating electron-rich functional groups into organic semiconductors can combine the advantages of Lewis bases and organic semiconductors to achieve defect passivation of perovskite films and interfacial charge transport improvement simultaneously. However, interlayers generated by organic semiconductors are often destroyed during the deposition of the hole transport layer (HTL) in n–i–p PSCs. This prevents the accurate evaluation of interfacial passivation effects. Herein, a pyromellitic derivative, 2,6-bis(4-(bis(4-methoxyphenyl)amino)phenyl)pyrrolo[3,4-f]isoindole-1,3,5,7(2 H,6 H)-tetraone (Pyr-TPA), containing four carbonyl groups that can passivate defects and enhance hole transport while simultaneously acting as a stable interlayer at the perovskite/HTL interface due to its ideal solubility profile is introduced. As a result, Pyr-TPA as an interlayer can minimize nonradiative recombination loss, resulting in a power conversion efficiency of up to 24.16%. Additionally, the interfacial Pyr-TPA passivation layer also exhibits strong resistance to moisture and ion migration, leading to enhanced long-term ambient stability of PSCs based on this material. Findings provide valuable insights into developing efficient and stable PSCs with simple and effective organic semiconductor interfacial passivation materials.

Publication date: September 2023

Source: Nano Energy, Volume 114

Author(s): Yun Tang, Yuchao Zhang, Xinming Zhou, Ting Huang, Kai Shen, KangNing Zhang, Xiaoyan Du, Tingting Shi, Xiudi Xiao, Ning Li, Christoph J. Brabec, Yaohua Mai, Fei Guo

Surface treatment of triple-halide perovskite layers with piperazinium iodide enables highly efficient tandem solar cells.

Phosphonic acids minimize charge-transfer losses and improve coating of perovskites on micropyramidal silicon substrates.

Semitransparent perovskite solar cells are regulated by transparent electrodes and the perovskite absorber. The color semitransparent perovskite solar cells can be realized through optical management. If the semitransparent perovskite solar cells are applied to the glass curtain wall, it will bring aesthetics and generate photovoltaic power.

Semitransparent perovskite solar cells (ST-PSCs) are highly promising for application in building-integrating photovoltaics (BIPVs) due to their potential in tunable transparency and color. However, the comprehensive performance of ST-PSCs falls quite short of the ideal requirements for BIPV. Herein, more attention is to review how to balance transparency and power conversion efficiency for ST-PSCs. Optimizing transparent electrodes and the active layers are interesting strategies to achieve the transparency required by devices. In addition, to obtain color ST-PSCs, tuning the bandgap of perovskite layers and designing the optical structure of the electrode are effective strategies. Last but not least, three significant optical evaluation indexes of ST-PSCs are described in the supporting information: average visible transmittance, color rendering index, and light utilization efficiency.

We propose a novel hole-transporting bilayer as a selective contact for fully ambient printed perovskite solar cells with carbon electrodes. We selectively deposit two hole-transporting materials with an energetic offset between their HOMO levels and achieve not only improved power conversion efficiencies compared with conventional devices with single hole-transporting layer but also excellent operational stability. Such interfacial design shows great potential in developing highly cost-effective perovskite photovoltaics.

Nature Energy, Published online: 03 July 2023; doi:10.1038/s41560-023-01288-7

The efficiency and stability of methylammonium- and bromide-free perovskite inverted solar cells need improvement. Now, Chen et al. combine a Lewis-based additive with a fluorocarbon-modified ammonium salt to reduce defects in the perovskite, increasing the device performance.

A bridge link strategy for buried surface with perovskite provides superior defect passivation and energy alignment by employing the rationally selected mediator of glycocyamine. The interface enables slower crystal growth with enlarged grain size and absence of pinholes. The modified planar perovskite solar cell exhibits a champion power conversion efficiency of 24.70 % with an open circuit voltage of 1.194 V and retains 89 % of its initial efficiency after heating at 85 °C for 800 h.

Abstract

The interface of perovskite solar cells (PSCs) is significantly important for charge transfer and device stability, while the buried interface with the impact on perovskite film growth has been paid less attention. Herein, we use a molecular modifier, glycocyamine (GDA) to build a molecular bridge on the buried interface of SnO₂/perovskite, resulting in superior interfacial contact. This is achieved through the strongly interaction between GDA and SnO₂, which also appreciably modulates the energy level. Moreover, GDA can regulate the perovskite crystal growth, yielding perovskite film with enlarged grain size and absence of pinholes, exhibiting substantially reduced defect density. Consequently, PSCs with GDA modification demonstrate significant improvement of open circuit voltage (close to 1.2 V) and fill factor, leading to an improved power conversion efficiency from 22.60 % to 24.70 %. Additionally, stabilities of GDA devices under maximum power point and 85 °C heat both perform better than the control devices.

An origin of the instability of narrow-bandgap perovskite solar cells is found to be the unstable interface between acidic PEDOT:PSS and basic additive SnF₂ in the perovskite. The above interface is stabilized by modifying the acidity of PEDOT:PSS layer with NH₃∙H₂O. The derived all-perovskite tandem solar cells exhibit high efficiency of 25.3% with excellent stability.

Abstract

Developing all-perovskite tandem solar cells has been proved to be an effective approach to boost the efficiency beyond the Shockley–Queisser limit. However, the Sn-based narrow-bandgap (NBG) perovskite solar cells (PSCs) suffer from the relatively low photostability, which limits their further application in all-perovskite tandem solar cells. In this work, the instability of NBG PSCs is found to come from the commonly used acidic hole transporting material PEDOT:PSS, which reacts with the indispensable basic additive SnF₂ in the perovskite layer. By acidity control of PEDOT:PSS via aqueous ammonia, the NBG PSCs yield an efficiency of 22.0% with much improved photostability, which can maintain 91.3% of the initial value after 800 h illumination under AM 1.5G. As an application, the corresponding all-perovskite tandem cells exhibit a stabilized efficiency of 25.3% with 92% remaining after 560 h illumination. This work reveals an origin of instability of NBG PSCs and provides an effective approach to enhance the device stability, which can promote the development of all-perovskite tandem solar cells.

By optimizing the transparent rear electrode, we achieved highly efficient single-junction bifacial perovskite solar cells (PSCs). Under concurrent bifacial illumination conditions, we achieved stabilized power outputs of 26.9, 28.5, and 30.1 mW/cm2 under albedos of 0.2, 0.3, and 0.5, respectively—surpassing state-of-the-art monofacial single-junction PSCs and comparable to all-perovskite monofacial and bifacial tandem PSCs. Bifacial perovskite photovoltaics technology has the potential to outperform its monofacial counterparts with higher energy yields and lower levelized cost of energy.

A dual-interface modulation strategy is demonstrated using functional covalent organic frameworks to fabricate the high-performance perovskite solar cells; a champion efficiency of 24.26% is obtained together with enhanced long-term stability due to released tensile stress, reduced trap state density, as well as enhanced resistance of humidity and ultraviolet irradiation.

Abstract

Dual-interface modulation including buried interface as well as the top surface has recently been proven to be crucial for obtaining high photovoltaic performance in lead halide perovskite solar cells (PSCs). Herein, for the first time, the strategy of using functional covalent organic frameworks (COFs), namely HS-COFs for dual-interface modulation, is reported to further understand its intrinsic mechanisms in optimizing the bottom and top surfaces. Specifically, the buried HS-COFs layer can enhance the resistance against ultraviolet radiation, and more importantly, release the tensile strain, which is beneficial for enhancing device stability and improving the order of perovskite crystal growth. Furthermore, the detailed characterization results reveal that the HS-COFs on the top surface can effectively passivate the surface defects and suppress non-radiation recombination, as well as optimize the crystallization and growth of the perovskite film. Benefiting from the synergistic effects, the dual-interface modified devices deliver champion efficiencies of 24.26% and 21.30% for 0.0725 cm² and 1 cm²-sized devices, respectively. Moreover, they retain 88% and 84% of their initial efficiencies after aging for 2000 h under the ambient conditions (25 °C, relative humidity: 35–45%) and a nitrogen atmosphere with heating at 65 °C, respectively.

A facile preburied cesium formate (CsFo) strategy is developed to stabilize the bottom side of perovskite by fully releasing the in-plane tensile strain at buried interface. Meanwhile, the CsFo eliminates the voids and reduces the defects as well as facilitates the charge extraction. The optimized formamidinium (FA)-based perovskite solar cell (PSC) exhibits impressive efficiency and stability.

Abstract

The fragile bottom side of perovskite films is demonstrated to be harmful to the efficiency and stability of perovskite solar cells (PSCs) because the carrier extraction and recombination can be significantly influenced by the easily formed strain, voids, and defects on the bottom side. Nevertheless, the bottom side of perovskite films is usually overlooked because it remains a challenge to directly characterize and modify the bottom side. Herein, a facile and effective strategy is reported to stabilize the bottom side via preburying cesium formate (CsFo) into the SnO₂ electron transport layer (ETL). It is found that the synergistic effect of cesium cation (Cs⁺) and formate anion (HCOO⁻) causes strain relaxation, void elimination, and defects’ reduction, which further facilitate the charge extraction. Consequently, the champion power conversion efficiency (PCE) of formamidinium (FA)-based PSCs is increased from 23.34% to 24.50%. Meanwhile, the ultraviolet (UV), thermal, and operational stability are also enhanced. Finally, formamidinium–cesium (FACs)-based PSCs are investigated to confirm the effectiveness of this preburied CsFo strategy, and the optimal device exhibits a champion PCE of 25.03% and a remarkably high fill factor (FF) of 85.65%.

By comparing and analyzing nicotinamide (NA) and its derivative 6-methylnicotinamide (CNA), the effects of molecular dipole and electronic configuration on perovskite defect passivation and photovoltaic performance of perovskite solar cells are systematically studied. CNA with its high-density electron cloud distribution improves thepower conversion efficiency to 24.33%, and improves the environment, thermal and optical stability of devices.

Abstract

The design of additives mainly involves selection of functional groups with coordination relationships with defects in perovskite materials. However, it is particularly important to further adjust the geometrical configuration and electronic structure of an additive. Here, the nicotinamide (NA) and its derivative 6-Methylnicotinamide (CNA) with electron-donor functional groups are comparatively analyzed to investigate the effect of molecular dipole and electronic configuration on the defect passivation of perovskite absorbers and the photovoltaic properties of perovskite solar cells (PSCs). Theoretical calculations demonstrate that the CNA molecule with its large molecular dipole combine with the undercoordinated Pb²⁺ ions in perovskite to form a higher binding energy, which is beneficial to improve the formation energy of Pb-related defects. Experimental characterization confirms that the CNA molecule significantly enhances the coordination effect between acylamino and undercoordinated defective Pb²⁺ cations, which is conducive to obtain high-quality, low-defect density of state, large grain size, and smooth surface perovskite absorbers. Thanks to the electronic configuration and electronic cloud distribution of CNA molecules, the PSCs yield impressive efficiency as high as 24.33% with excellent environmental storage, heat, and light stabilities. This research provides a research basis for designing additives with steric-charge-dependence to assist perovskite photovoltaics.

Application of solution-processed doped Spiro-OMeTAD hole transport layers (HTLs) is being held back by poor stability and unsatisfied scalability. Herein, a versatile molecular implantation-assisted sequential doping approach is developed to improve the spatial doping uniformity and fabricate all-evaporated HTL. The resultant devices achieve a record efficiency of 23.4%, and exhibit impressive stability both in ambient and working conditions.

Abstract

Although hole transport layers (HTLs) based on solution-processed doped Spiro-OMeTAD are extremely popular and effective for their remarkable performance in n-i-p perovskite solar cells (PSCs), their scalable application is still being held back by poor chemical stability and unsatisfied scalability. Essentially, the volatile components and hygroscopic nature of ionic salts often cause morphological deformation that deteriorate both device efficiency and stability. Herein, a simple and effective molecular implantation-assisted sequential doping (MISD) approach is strategically introduced to modulate spatial doping uniformity of organic films and fabricate all evaporated Spiro-OMeTAD layer in which phase-segregation free HTL is achieved accompanied with high molecular density, uniform doping composition, and superior optoelectronic characteristics. The resultant MISD-based devices attain a record power conversion efficiency (PCE) of 23.4%, which represents the highest reported value among all the PSCs with evaporated HTLs. Simultaneously, the unencapsulated devices realize considerably enhanced stability by maintaining over 90% of their initial PCEs in the air for 5200 h and after working at maximum power point under illumination for 3000 h. This method provides a facile way to fabricate robust and reliable HTLs toward developing efficient and stable perovskite solar cells.

The impact of the alkyl chains of the alkylammonium pesudohalide additives, such as methylammonium thiocyanate (MASCN), ethylammonium thiocyanate (EASCN), and propylammonium thiocyanate (PASCN), on the microstructures, optoelectronic properties of the Dion-Jacobson perovskite films and the performance of the solar cells is investigated. Among the additives, EASCN produces the most efficient and stable solar cells.

Abstract

Dion-Jacobson perovskite (DJP) films suffer from the high structural disorder and non-compact morphology, leading to inefficient and unstable solar cells (SCs). Here, how the alkyl chains of alkylammonium pseudohalide additives including methylammonium thiocyanate (MASCN) and ethylammonium thiocyanate (EASCN), and propylammonium thiocyanate (PASCN), impact the microstructures, optoelectronic properties and the performance of the solar cells is investigated. These additives substantially improve the structural order and the morphology of the DJP films, yielding more efficient and stable solar cells than the control device. They behave quite differently in modifying the morphological features. Particularly, EASCN outstands the additives in terms of the superior morphology, which is compact and uniform and consists of the largest flaky grains. Consequently, the corresponding device delivers a power conversion efficiency (PCE) of 15.27% and maintains ≈86% of the initial PCE after aging in the air for 182 h. Conversely, MASCN as an additive produces uneven DJP film and the device maintains only 46% of the initial PCE. PASCN as an additive produces the finest grains in the DJP film, and the corresponding device yields a PCE of 11.95%. From the economical point of view, it costs 0.0025 yuan per device for the EASCN additive, allowing for cost-effective perovskite solar cells.

The concept of “quantum confinement breaking” in 2D perovskites is proposed based on theoretical calculation and experimental results. An intensive orbital coupling between the bithiophenemethylammonium (BThMA) spacer and adjacent inorganic layers in (BThMA)₂PbI₄ is observed, whereas no such interactions exist when using a biphenemethylammonium-based spacer. The reducing or eliminating of the quantum confinement in 2D perovskite promotes efficient charge transport.

Abstract

2D Ruddlesden–Popper perovskites have become emerging photovoltaic materials due to their intrinsic structure stability. Here, a concept of “quantum confinement breaking” in 2D perovskites is proposed using organic semiconductor spacers with suitable energy levels based on theoretical calculation and experimental results. An interesting finding is that there is intensive orbital coupling between the bithiophenemethylammonium (BThMA) spacer and adjacent inorganic layers in (BThMA)₂PbI₄, resulting in the breaking of the multiple quantum well structure. In comparison, no orbital interactions exist in (BPhMA)₂PbI₄ due to the wide bandgap of the biphenemethylammonium (BPhMA) spacer. Benefitting from the improved film quality, increased dielectric constant, and reduced binding energy, the (BThMA)₂MA _{n −1}Pb _n I_{3 n +1} (n = 5) perovskite-based device displays an outstanding power conversion efficiency (PCE) of 18.05%, which is much higher than that of the BPhMA-based device (PCE = 12.69%) and among the best efficiency in 2D PSCs based on long conjugated spacers. The results provide an important implication for the effects of orbital interactions between organic semiconductor spacers and the adjacent [PbI₆]⁴⁻ octahedron layer on the performance of 2D perovskite solar cells and other optoelectronic devices.

The PYBA cation is used as a template for the crystallization of FAPbI₃ perovskite, which induces a highly oriented crystal and a pure α-phase film. The external compression strain provided by the PYBA pairs compensates for the inherent tension strain of the FAPbI₃ crystals. As a result, the strain-regulated formamidinium PSC exhibits an improved PCE.

Abstract

Formamidinium lead iodide (FAPbI₃) perovskite possesses an ideal optical bandgap and is a potential material for fabricating the most efficient single-junction perovskite solar cells (PSCs). Nevertheless, large formamidinium (FA) cations result in residual lattice strain, which reduces the power conversion efficiency (PCE) and operational stability of PSCs. Herein, the modulation of lattice strain in FAPbI₃ crystals via a π-conjugated organic amine, i.e., 4-pyrene oxy butylamine (PYBA), is proposed. PYBA pairs at the grain boundary serve as a template for the crystallization of FAPbI₃ perovskite, thereby inducing a highly oriented crystal and a pure α-phase film. The PYBA pairs with strong π–π interactions provide a solid fulcrum for external compression strain, thus compensating for the inherent tension strain of FAPbI₃ crystals. The strain release elevates the valence band of the perovskite crystals, thereby decreasing the bandgap and trap density. Consequently, the PYBA-regulated FAPbI₃ PSC achieves an excellent PCE of 24.76%. Moreover, the resulting device exhibits improves operational stability and maintains over 80% of its initial PCE after 1500 h under maximum power point tracking conditions.

Disordered Sn/Pb ratio and heterojunctions in perovskite film can be suppressed through selective molecular interaction. Hydrazine sulfate (HS) is introduced in Sn perovskite precursor and reduces the crystallization rate of tin perovskite to the level of lead analog. Therefore, a Sn-Pb perovskite film with uniform component and energy distribution, as well as devices with low recombination loss are achieved.

Abstract

Tin-lead (Sn-Pb) perovskite solar cells (PSCs) with near-ideal bandgap still lag behind the pure lead PSCs. Disordered heterojunctions caused by inhomogeneous Sn/Pb ratio in the binary perovskite film induce large recombination loss. Here, an Sn-Pb perovskite film is reported with homogeneous component and energy distribution by introducing hydrazine sulfate (HS) in Sn perovskite precursor. HS can form hydrogen bond network and coordinate with FASnI₃ thus no longer bond with Pb²⁺, which reduces the crystallization rate of tin perovskite to the level of lead analog. The strong bonding between SO₄ ²⁻ and Sn²⁺ can also suppress its oxidation. As a result, the Sn-Pb PSCs with HS exhibit a significantly improved V_OC of 0.91 V along with a high efficiency of 23.17%. Meanwhile, the hydrogen bond interaction network, strong bonding between Sn²⁺ and sulfate ion also improve the thermal, storage, and air stability of resulting devices.

An in situ polymerizing internal encapsulation (IPIE) strategy is developed to realize robust perovskite films with fewer structural defects, high water resistance, ion migration inhibition, and strain release. The PSCs exhibit an impressive efficiency of 24.12% and excellent environmental and mechanical stability. Moreover, toxic lead element leakage is undermined by the polymerized network barrier and chemical immobilization effect.

Abstract

Despite the outstanding power conversion efficiency (PCE) of perovskite solar cells (PSCs) achieved over the years, unsatisfactory stability and lead toxicity remain obstacles that limit their competitiveness and large-scale practical deployment. In this study, in situ polymerizing internal encapsulation (IPIE) is developed as a holistic approach to overcome these challenges. The uniform polymer internal package layer constructed by thermally triggered cross-linkable monomers not only solidifies the ionic perovskite crystalline by strong electron-withdrawing/donating chemical sites, but also acts as a water penetration and ion migration barrier to prolong shelf life under harsh environments. The optimized MAPbI₃ and FAPbI₃ devices with IPIE treatment yield impressive efficiencies of 22.29% and 24.12%, respectively, accompanied by remarkably enhanced environmental and mechanical stabilities. In addition, toxic water-soluble lead leakage is minimized by the synergetic effect of the physical encapsulation wall and chemical chelation conferred by the IPIE. Hence, this strategy provides a feasible route for preparing efficient, stable, and eco-friendly PSCs.