Flexible Perovskite Solar Cells Research Articles

Pre‐Buried ETL with Bottom‐Up Strategy Toward Flexible Perovskite Solar Cells with Efficiency Over 23%

AbstractWith rapid development of photovoltaic technology, flexible perovskite solar cells (f‐PSCs) have attracted much attention for their light weight, high flexibility and portability. However, the power conversion efficiency (PCE) achieved so far is not yet comparable to that of rigid devices. This is mainly due to the great challenge of depositing homogeneous and high‐quality perovskite films on flexible substrate. In this study, the pre‐buried 3‐aminopropionic acid hydroiodide (3AAH) additives into the electron transport layer (ETL) and modified the ETL/perovskite (PVK) interface by a bottom‐up strategy. 3AAH treatment induced a templated perovskite grain growth and improved the quality of the ETL. By this, the residual stresses generated in PVK during the annealing‐cooling process are released and converted into micro‐compressive stresses. As a result, the defect density of f‐PSCs with pre‐buried 3AAH is reduced and the photovoltaic performance is greatly improved, reaching an exceptional PCE of 23.36%. This strategy provides a new idea to bridge the gap between flexible and rigid devices.

High performance flexible Sn-Pb mixed perovskite solar cells enabled by a crosslinking additive

Flexible perovskite solar cells (PSCs) have drawn increasing attention due to their promising applications for wearable electronics and aerospace applications. However, the efficiency and stability of flexible PSCs still lag behind their rigid counterparts. Here, we use N,N-dimethyl acrylamide (DMAA) to in situ synthesize cross-linking polymer for flexible Sn–Pb mixed PSCs. DMAA can gather at grain boundary as a scaffold to regulate the crystallization of perovskite and reduce defects. The rigid and flexible Sn–Pb mixed PSCs showed efficiencies of 16.44% and 15.44%, respectively. In addition, the flexible Sn–Pb mixed PSCs demonstrated excellent bending durability, which retained over 80% of the original efficiency after 5000 bending cycles at a radius of 5 mm.

Perovskite Grain-Boundary Manipulation Using Room-Temperature Dynamic Self-Healing "Ligaments" for Developing Highly Stable Flexible Perovskite Solar Cells with 23.8% Efficiency.

Flexible perovskite solar cells (pero-SCs) are the best candidates to complement traditional silicon SCs in portable power applications. However, their mechanical, operational, and ambient stabilities are still unable to meet the practical demands because of the natural brittleness, residual tensile strain, and high defect density along the perovskite grain boundaries. To overcome these issues, a cross-linkable monomer TA-NI with dynamic covalent disulfide bonds, H-bonds, and ammonium is carefully developed. The cross-linking acts as "ligaments" attached on the perovskite grain boundaries. These "ligaments" consisting of elastomers and 1D perovskites can not only passivate the grain boundaries and enhance moisture resistance but also release the residual tensile strain and mechanical stress in 3D perovskite films. More importantly, the elastomer can repair bending-induced mechanical cracks in the perovskite film because of dynamic self-healing characteristics. The resultant flexible pero-SCs exhibit promising improvements in efficiency, and record values (23.84% and 21.66%) are obtained for 0.062and 1.004cm2 devices; the flexible devices also show overall improved stabilities with T90 >20000bending cycles, operational stability with T90 >1248h, and ambient stability (relative humidity=30%) with T90 >3000h. This strategy paves a new way for the industrial-scale development of high-performance flexible pero-SCs.

Synergistic Toughening and Self‐Healing Strategy for Highly Efficient and Stable Flexible Perovskite Solar Cells

AbstractHalide perovskites are qualified to meet the flexibility demands of optoelectronic field because of their merits of flexibility, lightness, and low cost. However, the intrinsic defects and deformation‐induced ductile fracture in both perovskite and buried interface significantly restrict the photoelectric performance and longevity of flexible perovskite solar cells (PVSCs). Here, a dual‐dynamic cross‐linking network is schemed to boost the photovoltaic efficiency and mechanical stability of flexible PVSCs by incorporating natural polymerizable small molecule α‐lipoic acid (LA). The LA therein can be autonomously ring‐opening polymerized through dynamic disulfide bonds and hydrogen bonds, concurrently forming coordination bonds to interact with perovskite component. Importantly, the polymerization product can serve as efficacious passivating and toughening agents to simultaneously optimize interfacial contact, enhance perovskite crystallinity and sustain robust mechanical bendability. Subsequently, the rigid (or flexible) p‐i‐n device realizes a champion efficiency of 22.43% (or 19.03%) with prominent operational stability. Moreover, the dual‐dynamic cross‐linking network endows PVSCs with bendability and self‐healing capacity, allowing the optimized devices to retain >80% efficiency after 3000 bending cycles, and subsequently restore to ≈95% of its initial efficiency under mild heat‐treatment. This toughening and self‐healing strategy provides a facile and efficient path to prolong operational lifetime of flexible device.

Slot-Die-Coated Active Layer for Printed Flexible Back-Contact Perovskite Solar Cells

Perovskites have already shown potential as active layers in photovoltaic applications. Furthermore, a low-cost and simple solution processing technology allows perovskites to be used in flexible and printed electronics. Perovskite solar cells (PSC) with a back-contact (BC) structure, in which the electrode system is based on a quasi-interdigitated back-contact (QIBC) design, promise to increase the power conversion efficiency (PCE) of devices beyond those that can be obtained using PSCs with a traditional sandwich structure. While the spin-coating technique is used to deposit the perovskite layer of lab-scale BC PSCs, the application of large-area printing techniques to deposit the perovskite layer of such devices is yet to be explored. Therefore, this work demonstrates an application of the slot-die coating technique to print the perovskite active layer of BC PSCs with QIBC electrodes on flexible polymer substrates. The morphology of the obtained perovskite films on QIBC electrodes are investigated and the primary photoelectric parameters of the resulting BC PSCs are measured. The charge carrier recombination processes in the fabricated BC PSCs are investigated and the dominant mechanism for carrier loss in the devices is determined. The findings of the work give an insight into the properties of the slot-die-coated perovskite active layer of BC PSCs and points to exciting new research opportunities in this direction.

Wearable perovskite solar cells by aligned liquid crystal elastomers

In a flexible perovskite solar cell, the bottom interface between perovskite and the electron-transporting layer is critical in determining its efficiency and reliability. High defect concentrations and crystalline film fracturing at the bottom interface substantially reduce the efficiency and operational stability. In this work, a liquid crystal elastomer interlayer is intercalated into a flexible device with the charge transfer channel toughened by the aligned mesogenic assembly. The molecular ordering is instantly locked upon photopolymerization of liquid crystalline diacrylate monomers and dithiol-terminated oligomers. The optimized charge collection and the minimized charge recombination at the interface boost the efficiency up to 23.26% and 22.10% for rigid and flexible devices, respectively. The liquid crystal elastomer-induced suppression of phase segregation endows the unencapsulated device maintaining >80% of the initial efficiency for 1570 h. Moreover, the aligned elastomer interlayer preserves the configuration integrity with remarkable repeatability and mechanical robustness, which enables the flexible device to retain 86% of its original efficiency after 5000 bending cycles. The flexible solar cell chips are further integrated into a wearable haptic device with microneedle-based arrays of sensors to demonstrate a pain sensation system in virtual reality.

Concurrent Top and Buried Surface Optimization for Flexible Perovskite Solar Cells with High Efficiency and Stability

AbstractAlthough much progress is made toward enhancing the efficiency of perovskite solar cells (PSCs), their operational reliability, particularly their mechanical stability, which is a crucial factor for flexible PSCs (f‐PCSs), has not attracted sufficient attention. The defects in the perovskite layer, especially on the top and the buried surface of the perovskite layer, can induce perovskite fracture, highly limiting the performance of f‐PSCs. Herein, a novel multifunctional organic salt, metformin hydrochloride, which can passivate cationic and anionic defects, is incorporated on both the top and buried surfaces of perovskite layer to suppress defects. As a result, a power conversion efficiency (PCE) of 24.40% for rigid PSCs and a PCE of 22.04% for f‐PSCs are achieved. Simultaneously, the device can retain 90% and 80% of the initial efficiency after 1000 h of light illumination and 10 000 bending cycles, respectively, showing excellent operational stability. This study may provide a global way to design a passivation strategy and fabricate flexible perovskite solar cells with high efficiency and stability.

Effective light management, stretchable and transparent nanofiber electrode via the incorporation of phosphors into composite nanofibers for wearable perovskite solar cells

The flexible transparent electrode is a crucial component of wearable photoelectric devices, and has a significant influence on the performance and development of wearable devices. Here, a phosphor/polyimide/polyurethane@silver composite nanofiber (NF) web electrode was fabricated by electrospinning and magnetron sputtering for wearable photoelectric devices. The electrode demonstrated a promising light management ability with converting ultraviolet light to visible light, high conductivity with sheet resistance of 22.1 Ω/square, and high transparency with transmittance of over 80%. Besides, the electrode possessed an excellent stretched capacity with tensile strain of over 100%, and tensile stability with the resistance increased by ∼75% after 500 stretching cycles at the tensile stain of 50%. As a result, a flexible perovskite solar cell (PSC) was assembled by using the NF web electrode, and possessed the power conversion efficiency of 3.47%, which is higher than that of PSCs based on electrodes without phosphor. Furthermore, the flexible PSCs exhibited promising mechanical stability under bending, and could serve as wearable devices. This work provides a feasible and promising method to prepare lightweight, stretchable, light management, and transparent electrodes for photoelectric devices, and may facilitate the development of wearable photoelectric devices.

Functional Layers of Inverted Flexible Perovskite Solar Cells and Effective Technologies for Device Commercialization

Perovskite solar cells (PSCs) are now one of the most promising solar cells due to advantages such as high‐power conversion efficiency (PCE), low cost, and ease of fabrication. Among PSCs, flexible perovskite solar cells (FPSCs) are lightweight and bendable, making them easier to transport and install than rigid PSCs, and hence can be used in wearable and portable electronics, space energy systems, multifunctional integrated buildings, unmanned systems, and other applications. Compared with regular n–i–p FPSCs, inverted p–i–n FPSCs possess advantages of reliable operational stability, reduced hysteresis effect, low‐temperature fabrication process, and strong potential for tandem devices. At present, the PCEs of single‐junction and tandem‐inverted FPSCs have reached 21.76% and 24.7%, respectively, indicating promising commercial applications. In this review, first, the developments of device functional layers including flexible substrates, flexible conductive electrodes, charge transport layers, and perovskite active layers in inverted FPSCs are elucidated and discussed thoroughly. Then, the technologies for accelerating commercialization of inverted FPSCs are summarized in detail. Finally, perspectives on the development and commercialization of inverted FPSCs are provided.

In situ crosslinking-assisted perovskite grain growth for mechanically robust flexible perovskite solar cells with 23.4% efficiency

•Enhanced the crystallization of flexible perovskite •Reduced Young’s modulus of perovskite film •Exhibited record efficiency •Exhibited excellent mechanical stability Flexible perovskite solar cells (pero-SCs) are the best candidates to complement silicon solar cells in the photovoltaic market. However, their power conversion efficiencies (PCEs) and mechanical stability are far behind the industry standards because of the uncontrollable growth of perovskites on plastic substrates and intrinsically high Young’s modulus. We explored an in situ crosslinking bis((3-methyloxetan-3-yl) methyl) thiophene-2,5-dicarboxylate along with perovskite growth, and its coordination ability and crosslinking temperature enabled the fine regulation of the quality of perovskite in real time. The resultant perovskite film exhibits an enlarged grain size, compact stacking, and a preferential crystal orientation. Moreover, the crosslinked elastomer polymer gathered at the perovskite grain boundaries can effectively release the mechanical stress. As a result, the flexible pero-SC based on this perovskite film achieved a record PCE of 23.4% (certified 22.9%), which is comparable with that of the rigid device. Importantly, the flexible pero-SCs also display a robust bending durability. Flexible perovskite solar cells (pero-SCs) are the best candidates to complement silicon solar cells in the photovoltaic market. However, their power conversion efficiencies (PCEs) and mechanical stability are far behind the industry standards because of the uncontrollable growth of perovskites on plastic substrates and intrinsically high Young’s modulus. We explored an in situ crosslinking bis((3-methyloxetan-3-yl) methyl) thiophene-2,5-dicarboxylate along with perovskite growth, and its coordination ability and crosslinking temperature enabled the fine regulation of the quality of perovskite in real time. The resultant perovskite film exhibits an enlarged grain size, compact stacking, and a preferential crystal orientation. Moreover, the crosslinked elastomer polymer gathered at the perovskite grain boundaries can effectively release the mechanical stress. As a result, the flexible pero-SC based on this perovskite film achieved a record PCE of 23.4% (certified 22.9%), which is comparable with that of the rigid device. Importantly, the flexible pero-SCs also display a robust bending durability.

Design and Simulation of Lead-free Flexible Perovskite Solar cell Using SCAPS-1D.

Despite perovskite solar cells’ rapidly increasing efficiency, industrializing and commercializing the device presents several challenges. Top among these is toxicity due to the material’s lead-based perovskite usage, which causes rapid degradation. Because of this challenge, researchers have recently become interested in lead-free perovskite materials. In this research, we investigate using the SCAPS simulation software to optimize a lead-free flexible solar cell. Lead (Pb), which belongs to group 14, can likely be replaced with bismuth (Bi), which belongs to group 15. In this study, the structure of the device is an n-i-p planar lead-free heterostructure flexible perovskite solar cell (FPSC) comprised of a Polyethylene Terephthalate/Indium Tin Oxide (PET/ITO) substrate; [6,6]-phenyl C61 butyric acid methyl ester (PCBM) Electron Transport Layer (ETL); methyl ammonium bismuth iodide (CH3NH3BiI3) as an absorber; Spiro-OMeTAD as a Hole Transport Layer (HTL); and silver (Ag) as the electrode. We optimised cell performance and efficiency with an absorber layer of 100 nm and an optimised temperature of 300 K. This absorber layer’s thickness and defect density were considered. The defect density of the FPSC is indirectly proportional to the device’s absorption coefficient (alpha). We obtained a power conversion efficiency (PCE) of 18.80%, a current density (JSC) of 35.59 mA/cm2, an open circuit voltage (VOC) of 0.633 V, and a fill factor (FF) of 83.43%. We also observed that the FF is inversely proportional to the thickness of the absorber layer of the FPSC.

Wide-Bandgap Perovskite Solar Cell Using a Fluoride-Assisted Surface Gradient Passivation Strategy.

Wide-bandgap (1.68 eV) perovskite solar cells (PSCs) are important components of perovskite/Si tandem devices. However, the efficiency of wide bandgap PSCs has been limited by their huge open-circuit voltage (VOC) deficit due to non-radiative recombination. Deep-level acceptor defects are identified as the major killers of VOC, and they can be effectively improved by passivation with ammonium salts. Theoretical calculation predicts that increasing the distance between F and -NH3+ of fluorinated ammonium can dramatically enhance the electropositivity of -NH3+ terminals, thus providing strong adsorption onto the negatively charged IA and IPb anti-site defects. Characterizations further confirm that surface gradient passivation employing p-FPEAI demonstrates the most efficient passivation effect. Consequently, a record-efficiency of 21.63% with the smallest VOC deficit of 441 mV is achieved for 1.68 eV-bandgap inverted PSCs. Additionally, a flexible PSC and 1 cm2 opaque device also deliver the highest PCEs of 21.02% and 19.31%, respectively.

Wide‐Bandgap Perovskite Solar Cell Using a Fluoride‐Assisted Surface Gradient Passivation Strategy

AbstractWide‐band gap (1.68 eV) perovskite solar cells (PSCs) are important components of perovskite/Si tandem devices. However, the efficiency of wide band gap PSCs has been limited by their huge open‐circuit voltage (Voc) deficit due to non‐radiative recombination. Deep‐level acceptor defects are identified as the major killers of Voc, and they can be effectively improved by passivation with ammonium salts. Theoretical calculation predicts that increasing the distance between F and −NH3+ of fluorinated ammonium can dramatically enhance the electropositivity of −NH3+ terminals, thus providing strong adsorption onto the negatively charged IA and IPb anti‐site defects. Characterizations further confirm that surface gradient passivation employing p‐FPEAI demonstrates the most efficient passivation effect. Consequently, a record‐efficiency of 21.63 % with the smallest Voc deficit of 441 mV is achieved for 1.68 eV‐band gap inverted PSCs. Additionally, a flexible PSC and 1 cm2 opaque device also deliver the highest PCEs of 21.02 % and 19.31 %, respectively.

Photovoltaics literature survey (No. 181)

Photovoltaics literature survey (No. 181)

Toward commercialization with lightweight, flexible perovskite solar cells for residential photovoltaics

Metal-halide perovskites have emerged as a promising class of next-generation solar cells. Here, we assess what lifetimes and efficiencies perovskite solar cells (PSCs) have to reach to lower the price of commercial residential photovoltaics (PVs) further. We find that using light and flexible substrates, as opposed to heavy and rigid ones, reduces the total installed system cost of PSCs, culminating in a lower balance of system (BOS) cost, as it is possible to use different mounting methods. Concretely, we analyze the scenario when the modules are directly placed onto a roof without requiring a racking system. This reduces both labor and material costs. Furthermore, it effectively lowers the necessary efficiency or lifetime of PSCs (T80 value) to achieve the same electricity cost as commercialized silicon. For 2021, we find that a rigid perovskite module with 17% efficiency would need at least 24 years to become competitive with residential-installed silicon. In comparison, a light, flexible module with the same efficiency would only need to last 19 years. In 2030, with the accordingly projected BOS costs, a 23% efficient perovskite module would need to last 24 years if rigid but only 17 years if flexible. Finally, we extend our analysis toward tandem structures with perovskite-silicon or all-perovskite tandem architectures. We find that flexible PSCs present a promising commercialization route because it can enable low manufacturing and BOS deployment costs, which opens up commercial viability at lower efficiencies or lifetimes. Metal-halide perovskites have emerged as a promising class of next-generation solar cells. Here, we assess what lifetimes and efficiencies perovskite solar cells (PSCs) have to reach to lower the price of commercial residential photovoltaics (PVs) further. We find that using light and flexible substrates, as opposed to heavy and rigid ones, reduces the total installed system cost of PSCs, culminating in a lower balance of system (BOS) cost, as it is possible to use different mounting methods. Concretely, we analyze the scenario when the modules are directly placed onto a roof without requiring a racking system. This reduces both labor and material costs. Furthermore, it effectively lowers the necessary efficiency or lifetime of PSCs (T80 value) to achieve the same electricity cost as commercialized silicon. For 2021, we find that a rigid perovskite module with 17% efficiency would need at least 24 years to become competitive with residential-installed silicon. In comparison, a light, flexible module with the same efficiency would only need to last 19 years. In 2030, with the accordingly projected BOS costs, a 23% efficient perovskite module would need to last 24 years if rigid but only 17 years if flexible. Finally, we extend our analysis toward tandem structures with perovskite-silicon or all-perovskite tandem architectures. We find that flexible PSCs present a promising commercialization route because it can enable low manufacturing and BOS deployment costs, which opens up commercial viability at lower efficiencies or lifetimes.

Novel dual-modification strategy using Ce-containing compounds toward high-performance flexible perovskite solar cells

The carrier non-radiative recombination loss caused by numerous interfacial defects existing between perovskite and neighboring charge transport layers, such as SnO2/perovskite and perovskite/spiro-OMeTAD, which greatly restricts the performance improvement of flexible perovskite solar cells (PSCs). Herein, we devised a novel dual-modification strategy using Ce-containing compounds (Ce2(SO4)3 and Ce(SO4)2) to minimize interfacial defect density at the interface of SnO2/perovskite and perovskite/spiro-OMeTAD respectively, thus enhancing the performance and stability of flexible PSCs. It was revealed that the introduction of Ce2(SO4)3 interface layer was conducive to ameliorating the electrical properties of SnO2 and significantly reducing the SnO2/perovskite interface defects. Moreover, the Ce(SO4)2 was adopted as a novel oxidant to achieve the rapid oxidation of spiro-OMeTAD, thus enhancing the hole mobility of bulk spiro-OMeTAD and suppressing perovskite/spiro-OMeTAD interface defects. Therefore, reduced non-radiative recombination losses near the two interfaces of the perovskite layer could be achieved by such a novel and comprehensive modification strategy. In consequence, the Ce-modified flexible and rigid PSCs achieved excellent photoelectric conversion efficiency (PCE) of 19.34 % and 22.62 %, respectively. Notably, the optimized flexible PSCs exhibited outstanding mechanical durability, and 83.2 % of the initial PCE was maintained after 3000 bending cycles.

Crosslinking and densification by plasma-enhanced molecular layer deposition for hermetic seal of flexible perovskite solar cells

Flexible perovskite solar cells are new energy devices with a promising future due to their numerous advantages, such as high defect tolerance, strong solar absorption and low non-radiative carrier recombination rates. However, their operational stability is still an ongoing challenge during upgrading, and their inferior moisture corrosion resistance is still a major issue for better performances. Thin-film encapsulation could effectively enhance the operational stability of perovskite solar cells but obtaining encapsulation films with excellent barrier performance always come at the expense of poor flexibility. Therefore, the development of novel encapsulation materials with both barrier performance and flexibility is urgent for the compatibility of flexible applications. In this work, "Plasma-Enhanced Molecular Layer Deposition" was used for the first time to prepare a highly cross-linked, densified flexible encapsulation material AlOC at 40 ℃ to break through the traditional technology. The resulting encapsulation material can be applied to flexible perovskite solar cells as a barrier film without any damage. The as-obtained encapsulation film exhibited a water vapor transmittance rate of 1.44 × 10−5 g m−2 day−1 and preserved 95 % of its initial barrier performance after 10,000 bends with a 3 mm bend radius. Such performance was the best among the reported thin-film encapsulation layers of flexible perovskite solar cells.

Spring‐Like Ammonium Salt Assisting Stress Release for Low‐Temperature Deposited FAPbI3 Films Toward Flexible Photovoltaic Application

AbstractThe substrates of conventional flexible perovskite solar cells (FPSCs) are thermoplastic polymer material polyethylene naphthalate (PEN), which will deform during high temperature annealing process. In addition, lead iodide (PbI2) permanently formed and the substrate undergoes reversible deformation from 20 °C to 200 °C and back to 20 °C. Therefore, to balance the substrate supporting capacity and the crystalline quality of narrow band gap α‐phase formamidinium lead iodide (α‐FAPbI3), an annealing process of 120 °C for 30 minutes is determined. Additionally, there will also be a large number of gaps and lattice strain at the perovskite grain boundaries during the annealing process as the FAPbI3 phase transition is accompanied by much lattice shrinkage. As a result, 1,6‐hexanediammonium diiodide (HADI) is chosen to passivate the defects and release the stress of perovskite film. Therefore, a recorded 1.4% extended stretch rate of the flexible film is attained. Finally, the champion PCE of 21.14% under AM 1.5G and 31.52% under 1062 lux is achieved after HADI treatment, accompanied by a better long‐term and mechanical stability. This study provides annealing process optimization and stress relief strategies for the further development of narrow band gap FPSCs.

Perylene Monoimide Phosphorus Salt Interfacial Modified Crystallization for Highly Efficient and Stable Perovskite Solar Cells

Reducing the interfacial defects of perovskite films is key to improving the performance of perovskite solar cells (PSCs). In this study, two kinds of perylene monoimide (PMI) derivative phosphonium bromide salts were designed and used as a multifunctional interface-modified layer in PSCs. These two molecules are inserted between SnO2 and perovskite to produce a bidirectional passivation effect. The interaction with SnO2 reduces the oxygen vacancy on the surface of SnO2 and tunes the energy level of the electron transport layer, making more matches with the perovskite layer. The modified layer can promote the growth of perovskite crystals and reduce the interfacial defects of the perovskite film. Furthermore, the power conversion efficiency (PCE) of PSCs increased from 19.49 to 22.85%, and the open-circuit voltage (VOC) increased from 1.06 to 1.14 V. At the same time, the PCE of the SnO2/PMI-TPP-based device remained 88% of the initial PCE after 240 h of continuous illumination. In addition, these two PMI derivatives with a quasi-planar structure can improve the flexibility of flexible PSCs. This study provided a new strategy for the interfacial modification of PSCs and a new insight into the application of flexible PSCs.

Rational Design of Ferroelectric 2D Perovskite for Improving the Efficiency of Flexible Perovskite Solar Cells Over 23.

Despite the great progress of flexible perovskite solar cells (f-PSCs), it still faces several challenges during the homogeneous fabrication of high-quality perovskite thin films, and overcoming the insufficient exciton dissociation. To the ends, we rationally design the two-dimensional (2D) perovskite based on pyridine heterocyclic ring as the organic interlayer. Through regulating its dipole moment by attaching the ammounium cation on different positions of the pyridine ring, we succeed to realize the ferroelectricity of the 2D perovskite. We uncover that incorporation of the ferroelectric 2D material into 3D perovskite induces an increased built-in electric field (BEF), which enhances the exciton dissociation efficiency and suppresses the nonradiative recombination in the device. Moreover, the 2D seeds could assist the 3D crystallization process by forming more homogeneous and highly-oriented perovskite crystals, and releasing the tensile stress in the film. As a result, an impressive power conversion efficiency (PCE) over 23% has been achieved by the 2D/3D based f-PSCs with outstanding ambient stability. Moreover, the ferroelectric 2D perovskite shows piezoelectricity as well, which intrigues an upshifted band-bending at the ITO/perovskite interface and decreased hole transport barriers. The device thus presents higher PCE under tensile-stresses, which opens new possibilities for developing highly-efficient f-PSCs.