Multifunctional succinate additive for flexible perovskite solar cells with more than 23% power-conversion efficiency

•FPSCs hold promise as power sources for flexible electronics and spacecraft•Succinate additives enable high-quality perovskite films with reduced microstrain•An efficiency of 25.4% has been achieved for perovskite solar cells•An efficiency of 23.6% has been achieved for FPSCs with excellent durability Flexible perovskite solar cells (FPSCs) have emerged as power sources in versatile applications owing to their high-efficiency characteristics, excellent flexibility, and relatively low cost. Nevertheless, undesired strain in perovskite films greatly impacts the power-conversion efficiency (PCE) and stability of PSCs, particularly in FPSCs. Herein, a novel multifunctional organic salt, methylammonium succinate, which can alleviate strain and reinforce grain boundaries, was incorporated into the perovskite film, leading to relaxed microstrain and a lower defect concentration. As a result, a PCE of 25.4% for rigid PSCs and a record PCE of 23.6% (certified 22.5%) for FPSCs have been achieved. In addition, the corresponding FPSCs exhibited excellent bending durability, maintaining ∼85% of their initial efficiency after bending at a 6 mm radius for 10 000 cycles. Flexible perovskite solar cells (FPSCs) have emerged as power sources in versatile applications owing to their high-efficiency characteristics, excellent flexibility, and relatively low cost. Nevertheless, undesired strain in perovskite films greatly impacts the power-conversion efficiency (PCE) and stability of PSCs, particularly in FPSCs. Herein, a novel multifunctional organic salt, methylammonium succinate, which can alleviate strain and reinforce grain boundaries, was incorporated into the perovskite film, leading to relaxed microstrain and a lower defect concentration. As a result, a PCE of 25.4% for rigid PSCs and a record PCE of 23.6% (certified 22.5%) for FPSCs have been achieved. In addition, the corresponding FPSCs exhibited excellent bending durability, maintaining ∼85% of their initial efficiency after bending at a 6 mm radius for 10 000 cycles. IntroductionPerovskite solar cells (PSCs) have emerged as a cost-effective photovoltaic technology, as is obvious from the power-conversion efficiency (PCE), which has surpassed 25.7%.1NREL best research-cell efficiency chart.https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies-rev220126.pdfGoogle Scholar,2Zhang F. Park S.Y. Yao C. et al.Metastable Dion-Jacobson 2D structure enables efficient and stable perovskite solar cells.Science. 2022; 375: 71-76Crossref PubMed Scopus (43) Google Scholar,3Li X. Zhang W. Guo X. et al.Constructing heterojunctions by surface sulfidation for efficient inverted perovskite solar cells.Science. 2022; 375: 434-437Crossref PubMed Scopus (90) Google Scholar,4Wang S. Tan L. Zhou J. et al.Over 24% efficient MA-free CsxFA1−xPbX3 perovskite solar cells.Joule. 2022; 6: 1344-1356Abstract Full Text Full Text PDF Scopus (6) Google Scholar With a high power-to-weight ratio and excellent flexibility, flexible PSCs (FPSCs) hold promise as power sources for flexible electronic devices, wearable equipment, and spacecraft.5Hu Y. Niu T. Liu Y. et al.Flexible perovskite solar cells with high power-per-weight: progress, application, and perspectives.ACS Energy Lett. 2021; 6: 2917-2943Crossref Scopus (35) Google Scholar With the experience accumulated in rigid PSCs, the PCE of FPSCs has reached over 22% in small areas6Zheng Z. Li F. Gong J. et al.Pre-buried additive for cross-layer modification in flexible perovskite solar cells with efficiency exceeding 22.Adv. Mater. 2022; 34: 2109879Crossref Scopus (11) Google Scholar,7Yang L. Feng J. Liu Z. et al.Record-efficiency flexible perovskite solar cells enabled by multifunctional organic ions interface passivation.Adv. Mater. 2022; 34: 2201681Crossref Scopus (26) Google Scholar and 15% in large areas.8Dai X. Deng Y. Van Brackle C.H. et al.Scalable fabrication of efficient perovskite solar modules on flexible glass substrates.Adv. Energy Mater. 2019; 10: 1903108Crossref Scopus (123) Google Scholar,9Chung J. Shin S.S. Hwang K. et al.Record-efficiency flexible perovskite solar cell and module enabled by a porous-planar structure as an electron transport layer.Energy Environ. Sci. 2020; 13: 4854-4861Crossref Google Scholar In addition, an increasing number of researchers have begun to explore the industrial roll-to-roll fabrication of FPSCs,10Othman M. Zheng F. Seeber A. et al.Millimeter-sized clusters of triple cation perovskite enables highly efficient and reproducible roll-to-roll fabricated inverted perovskite solar cells.Adv. Funct. Mater. 2022; 32: 2110700Crossref Scopus (9) Google Scholar,11Li H. Zuo C. Angmo D. et al.Fully roll-to-roll processed efficient perovskite solar cells via precise control on the morphology of PbI2:CsI layer.Nano-Micro Lett. 2022; 14: 79Crossref PubMed Scopus (3) Google Scholar showing a promising future in flexible photovoltaic applications.However, the PCE of FPSCs still lags far behind that of rigid PSCs, which can be mainly attributed to the inferior perovskite thin film quality on flexible substrates compared with that of glass substrates. The difference in the physical properties of glass substrates and flexible plastic substrates, such as thermal properties and surface roughness, increases the difficulty in obtaining high-quality perovskite thin films on plastic substrates.12Jung H.S. Han G.S. Park N.-G. Ko M.J. Flexible perovskite solar cells.Joule. 2019; 3: 1850-1880Abstract Full Text Full Text PDF Scopus (144) Google Scholar Additives comprising small molecules and polymers were employed in the perovskite precursor to regulate the perovskite crystallization process,13Feng J. Zhu X. Yang Z. et al.Record efficiency stable flexible perovskite solar cell using effective additive assistant strategy.Adv. Mater. 2018; 30: e1801418Crossref PubMed Scopus (297) Google Scholar improve crystallization, strengthen the perovskite crystals,14Hu X. Huang Z. Li F. et al.Nacre-inspired crystallization and elastic “brick-and-mortar” structure for a wearable perovskite solar module.Energy Environ. Sci. 2019; 12: 979-987Crossref Google Scholar and passivate defects.15Yang L. Xiong Q. Li Y. et al.Artemisinin-passivated mixed-cation perovskite films for durable flexible perovskite solar cells with over 21% efficiency.J. Mater. Chem. 2021; 9: 1574-1582Crossref Google ScholarDue to their polycrystalline nature, perovskite films also suffer from the influence of strain on the optoelectronic properties and stability.16Liu D. Luo D. Iqbal A.N. et al.Strain analysis and engineering in halide perovskite photovoltaics.Nat. Mater. 2021; 20: 1337-1346Crossref PubMed Scopus (64) Google Scholar,17Cheng Y. Ding L. Pushing commercialization of perovskite solar cells by improving their intrinsic stability.Energy Environ. Sci. 2021; 14: 3233-3255Crossref Google Scholar The residual strain is related to the stability of the perovskite18Rolston N. Bush K.A. Printz A.D. et al.Engineering stress in perovskite solar cells to improve stability.Adv. Energy Mater. 2018; 8: 1802139Crossref Scopus (162) Google Scholar and usually accelerates its degradation by increasing ion migration and reducing perovskite structural stability.19Zhao J. Deng Y. Wei H. et al.Strained hybrid perovskite thin films and their impact on the intrinsic stability of perovskite solar cells.Sci. Adv. 2017; 3: eaao5616Crossref PubMed Scopus (413) Google Scholar The microstrain, which originates from local lattice mismatch or misorientation and is related to the local lattice disorder and defects,20Wu J. Liu S.-C. Li Z. et al.Strain in perovskite solar cells: origins, impacts and regulation.Natl. Sci. Rev. 2021; 8: nwab047Crossref PubMed Scopus (42) Google Scholar is highly detrimental to the perovskite film and thus urgently needs to be mitigated. Although modifying the perovskite lattice by cation doping, such as Cd2+21Saidaminov M.I. Kim J. Jain A. et al.Suppression of atomic vacancies via incorporation of isovalent small ions to increase the stability of halide perovskite solar cells in ambient air.Nat. Energy. 2018; 3: 648-654Crossref Scopus (387) Google Scholar and MDA2+,22Kim G. Min H. Lee K.S. et al.Impact of strain relaxation on performance of α-formamidinium lead iodide perovskite solar cells.Science. 2020; 370: 108-112Crossref PubMed Scopus (537) Google Scholar has been demonstrated to lower microstrain for efficient and stable PSCs, the strain related to environmental effects such as bending, which is extremely important for FPSCs, cannot be alleviated by the above-mentioned method.In this work, we judiciously designed a novel multifunctional additive, methylammonium succinate (MS), to alleviate strain and passivate interface defects in a perovskite film. It has been reported that FAI-terminated surfaces and PbI2-terminated surfaces are stable surfaces in FAPbI3 grains.23Oner S.M. Sezen E. Yordanli M.S. et al.Surface defect formation and passivation in formamidinium lead triiodide (FAPbI3) perovskite solar sell absorbers.J. Phys. Chem. Lett. 2022; 13: 324-330Crossref PubMed Scopus (6) Google Scholar The two terminal carboxyl groups in MS can form hydrogen bonds with with two perovskite the the two carboxyl groups to the strain by environmental effects such as thermal stress and bending of flexible devices, leading to perovskite films with reduced defects and In addition, the carboxyl can with the at the surface of perovskite and the can for the in the reducing the number of As a result, we achieved a high PCE of 25.4% and 23.6% (certified 22.5%) for rigid and flexible PSCs, which is the reported PCE for FPSCs to In addition, the with the perovskite grain the grain and the strain the bending the FPSCs exhibited bending durability, ∼85% of their initial efficiency after 10 000 bending a 6 mm and grain of perovskite thin films are in defects and the of the and The multifunctional additive MS was designed to the defects and strengthen the grain by with two grain With two terminal carboxyl the succinate can with via hydrogen bonds and with in the grain the of the MS FAPbI3 perovskite thin films were fabricated by a as J. Li M. S. et to and form a 2D perovskite to the performance and stability of perovskite solar Energy. 2022; Scopus (11) Google M. Zhou J. Tan L. et as for high-efficiency perovskite solar Environ. Mater. 2022; Scopus Google Scholar The perovskite thin films are and for the films and with MS additive The surface electron of the control and film are in and small of MS additive in a and the in the control film were The that grain the control the film thin film electron of morphology and and of the control and films the the FAPbI3 perovskite and the of the properties of the films that MS incorporation the perovskite film quality The and from the are for that the MS additive the and of the FAPbI3 perovskite thin film. obvious the a and for the control a reduced defect in the perovskite film after MS that the MS to an thin film quality of the FAPbI3 perovskite the of the control and films on the substrates. It be that residual is in perovskite X. Y. et exceeding 6 in polycrystalline halide Mater. 2020; 32: PubMed Scopus Google J. X. et the of photovoltaic by organic 2021; PubMed Scopus Google Scholar the the or in the film. we that the MS be incorporated into the FAPbI3 lattice is mainly in the grain The structure of the MS enables to from were to the the MS and the FAPbI3 As in the for the two of the MS the cation to with the as by the of groups at after in the precursor the the to with the cation via hydrogen as by the of the of the groups in The of the in the the and In a the that can with and the of the we the of succinate on the two of perovskite surfaces and by are in in the FAI-terminated and in the PbI2-terminated which a the succinate and that MS with defects by hydrogen bonds with the formation of the MS and FAPbI3 that MS with ions and ions that groups with and in control and thin the effects of MS additives on the perovskite we to the residual strain of the perovskite C. Niu X. Y. et al.Strain engineering in perovskite solar cells and its impacts on 2019; 10: PubMed Scopus Google F. Deng X. F. et surface for efficient inverted perovskite solar cells with efficiency.J. Chem. 2020; PubMed Scopus Google Scholar control and were strain a this residual strain is by the thermal mismatch perovskite and Y. Liu S.-C. et strain in perovskite thin films 2020; PubMed Scopus Google Scholar the perovskite substrates, and were the in the microstrain in the perovskite films the from and Google is the at of the perovskite in the is the is the is the of the and is the The a and and the the microstrain in the The MS additive reduced the microstrain in the FAPbI3 thin films from to and As by the succinate can with and which in can lattice defects and at the grain boundaries, which be to alleviate the microstrain in the perovskite J. Liu S.-C. Li Z. et al.Strain in perovskite solar cells: origins, impacts and regulation.Natl. Sci. Rev. 2021; 8: nwab047Crossref PubMed Scopus (42) Google Scholar the on the of we the the G. Min H. Lee K.S. et al.Impact of strain relaxation on performance of α-formamidinium lead iodide perovskite solar cells.Science. 2020; 370: 108-112Crossref PubMed Scopus (537) Google from to we that the difference mainly from the microstrain and that the have that such microstrain in perovskite films is for efficiency and M.I. Kim J. Jain A. et al.Suppression of atomic vacancies via incorporation of isovalent small ions to increase the stability of halide perovskite solar cells in ambient air.Nat. Energy. 2018; 3: 648-654Crossref Scopus (387) Google G. Min H. Lee K.S. et al.Impact of strain relaxation on performance of α-formamidinium lead iodide perovskite solar cells.Science. 2020; 370: 108-112Crossref PubMed Scopus (537) Google Scholar The reduced microstrain is in with the reduced defect by G. Min H. Lee K.S. et al.Impact of strain relaxation on performance of α-formamidinium lead iodide perovskite solar cells.Science. 2020; 370: 108-112Crossref PubMed Scopus (537) Google Scholar which be for the performance of also strain analysis for the flexible The residual strain of the perovskite films on flexible substrates is that of rigid substrates, which be related to the film from the difference of flexible and rigid X. Deng Y. Van Brackle C.H. et al.Scalable fabrication of efficient perovskite solar modules on flexible glass substrates.Adv. Energy Mater. 2019; 10: 1903108Crossref Scopus (123) Google Scholar with the perovskite film, a lower residual strain is in the which is for the FPSCs. As in the of substrates. 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Li F. Gong J. et al.Pre-buried additive for cross-layer modification in flexible perovskite solar cells with efficiency exceeding 22.Adv. Mater. 2022; 34: 2109879Crossref Scopus (11) Google Scholar,7Yang L. Feng J. Liu Z. et al.Record-efficiency flexible perovskite solar cells enabled by multifunctional organic ions interface passivation.Adv. Mater. 2022; 34: 2201681Crossref Scopus (26) Google Scholar,9Chung J. Shin S.S. Hwang K. et al.Record-efficiency flexible perovskite solar cell and module enabled by a porous-planar structure as an electron transport layer.Energy Environ. Sci. 2020; 13: 4854-4861Crossref Google Q. M. Liu Y. et al.Flexible perovskite solar cells with and 2021; Full Text Full Text PDF Scopus (43) Google S. Li Z. Zhang J. et organic enabled efficient and flexible perovskite solar cells.Adv. Mater. 2021; Scopus Google Scholar The which reached in the The from the also reached which is with that from the we of for which a efficiency of with a power efficiency of at The and efficiency as the in Z. Li F. Gong J. et al.Pre-buried additive for cross-layer modification in flexible perovskite solar cells with efficiency exceeding 22.Adv. Mater. 2022; 34: 2109879Crossref Scopus (11) Google Scholar,7Yang L. Feng J. Liu Z. et al.Record-efficiency flexible perovskite solar cells enabled by multifunctional organic ions interface passivation.Adv. Mater. 2022; 34: 2201681Crossref Scopus (26) Google Scholar The of the performance is in with the on rigid The of the MS additive also demonstrated over PCE for the which be with S. Tan L. Zhou J. et al.Over 24% efficient MA-free CsxFA1−xPbX3 perovskite solar cells.Joule. 2022; 6: 1344-1356Abstract Full Text Full Text PDF Scopus (6) Google of the structure and the of the and photovoltaic of the and the of the of the PCE of control and of the stability of the PSCs was and the demonstrated to and the stability of the of the control of the initial the MS a degradation of The be attributed to the at the grain boundaries, which is the for were also in power at in a to the stability a the power of the of the initial PCE for the PCE of the control to of its initial after in with the stability in It is that the degradation in perovskite mainly from the grain J. Kim M. J. et engineering for perovskite solar 2021; PubMed Scopus Google Scholar As by the and the MS additive reduced the defects in the perovskite also the perovskite lattice structure via hydrogen at the grain boundaries, which to the X. M.I. C. et performance and stability of perovskite solar cells by with Chem. PubMed Scopus Google S. Li C. et perovskite solar cells with stability using 2019; PubMed Scopus Google stability of the solar cell The stability of the control and stability of the PSCs in a The bending stability of FPSCs 6 of the perovskite film from FPSCs after 10 000 bending at 6 with the by and by we a bending to the durability of and their efficiency the The control to of the initial PCE after 10 000 bending radius 6 the ∼85% of its initial PCE durability of the The stability of the be attributed to the grain and relaxed microstrain, which perovskite and defect M.I. Kim J. Jain A. et al.Suppression of atomic vacancies via incorporation of isovalent small ions to increase the stability of halide perovskite solar cells in ambient air.Nat. Energy. 2018; 3: 648-654Crossref Scopus (387) Google Z. X. Liu C. et and crystallization control via to the of perovskite solar cells with excellent Funct. Mater. 2017; Scopus Google Scholar the morphology of the perovskite film of the after the bending The and the were to the perovskite The in the control film is obvious and mainly and In the film and The film morphology also in the ambient in Q. M. Liu Y. et al.Flexible perovskite solar cells with and 2021; Full Text Full Text PDF Scopus (43) Google Scholar which the stability of the In addition, we a bending with a radius of Although that of the 6 mm bending to the a that of the control we demonstrated the incorporation of MS molecules into a perovskite thin film for high performance and stable The additive the microstrain in the FAPbI3 perovskite thin film, in quality and reduced defect of the thin film. PSCs were fabricated on rigid substrates and flexible substrates. FPSCs with MS incorporation an high efficiency of 23.6% (certified which as the in the reported to bending durability, ∼85% of the initial efficiency after 10 000 bending cycles. The efficiency and stability of the FPSCs are related to the microstrain of the perovskite film. a to microstrain by using a multifunctional organic additive that into the perovskite lattice the grain and the of molecules with such as hydrogen and can be designed to alleviate microstrain, which improve the and stability of FPSCs, the of this power to the for on IntroductionPerovskite solar cells (PSCs) have emerged as a cost-effective photovoltaic technology, as is obvious from the power-conversion efficiency (PCE), which has surpassed 25.7%.1NREL best research-cell efficiency chart.https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies-rev220126.pdfGoogle Scholar,2Zhang F. Park S.Y. Yao C. et al.Metastable Dion-Jacobson 2D structure enables efficient and stable perovskite solar cells.Science. 2022; 375: 71-76Crossref PubMed Scopus (43) Google Scholar,3Li X. Zhang W. Guo X. et al.Constructing heterojunctions by surface sulfidation for efficient inverted perovskite solar cells.Science. 2022; 375: 434-437Crossref PubMed Scopus (90) Google Scholar,4Wang S. Tan L. Zhou J. et al.Over 24% efficient MA-free CsxFA1−xPbX3 perovskite solar cells.Joule. 2022; 6: 1344-1356Abstract Full Text Full Text PDF Scopus (6) Google Scholar With a high power-to-weight ratio and excellent flexibility, flexible PSCs (FPSCs) hold promise as power sources for flexible electronic devices, wearable equipment, and spacecraft.5Hu Y. Niu T. Liu Y. et al.Flexible perovskite solar cells with high power-per-weight: progress, application, and perspectives.ACS Energy Lett. 2021; 6: 2917-2943Crossref Scopus (35) Google Scholar With the experience accumulated in rigid PSCs, the PCE of FPSCs has reached over 22% in small areas6Zheng Z. Li F. Gong J. et al.Pre-buried additive for cross-layer modification in flexible perovskite solar cells with efficiency exceeding 22.Adv. Mater. 2022; 34: 2109879Crossref Scopus (11) Google Scholar,7Yang L. Feng J. Liu Z. et al.Record-efficiency flexible perovskite solar cells enabled by multifunctional organic ions interface passivation.Adv. Mater. 2022; 34: 2201681Crossref Scopus (26) Google Scholar and 15% in large areas.8Dai X. Deng Y. Van Brackle C.H. et al.Scalable fabrication of efficient perovskite solar modules on flexible glass substrates.Adv. Energy Mater. 2019; 10: 1903108Crossref Scopus (123) Google Scholar,9Chung J. Shin S.S. Hwang K. et al.Record-efficiency flexible perovskite solar cell and module enabled by a porous-planar structure as an electron transport layer.Energy Environ. Sci. 2020; 13: 4854-4861Crossref Google Scholar In addition, an increasing number of researchers have begun to explore the industrial roll-to-roll fabrication of FPSCs,10Othman M. Zheng F. Seeber A. et al.Millimeter-sized clusters of triple cation perovskite enables highly efficient and reproducible roll-to-roll fabricated inverted perovskite solar cells.Adv. Funct. Mater. 2022; 32: 2110700Crossref Scopus (9) Google Scholar,11Li H. Zuo C. Angmo D. et al.Fully roll-to-roll processed efficient perovskite solar cells via precise control on the morphology of PbI2:CsI layer.Nano-Micro Lett. 2022; 14: 79Crossref PubMed Scopus (3) Google Scholar showing a promising future in flexible photovoltaic applications.However, the PCE of FPSCs still lags far behind that of rigid PSCs, which can be mainly attributed to the inferior perovskite thin film quality on flexible substrates compared with that of glass substrates. The difference in the physical properties of glass substrates and flexible plastic substrates, such as thermal properties and surface roughness, increases the difficulty in obtaining high-quality perovskite thin films on plastic substrates.12Jung H.S. Han G.S. Park N.-G. Ko M.J. Flexible perovskite solar cells.Joule. 2019; 3: 1850-1880Abstract Full Text Full Text PDF Scopus (144) Google Scholar Additives comprising small molecules and polymers were employed in the perovskite precursor to regulate the perovskite crystallization process,13Feng J. Zhu X. Yang Z. et al.Record efficiency stable flexible perovskite solar cell using effective additive assistant strategy.Adv. Mater. 2018; 30: e1801418Crossref PubMed Scopus (297) Google Scholar improve crystallization, strengthen the perovskite crystals,14Hu X. Huang Z. Li F. et al.Nacre-inspired crystallization and elastic “brick-and-mortar” structure for a wearable perovskite solar module.Energy Environ. Sci. 2019; 12: 979-987Crossref Google Scholar and passivate defects.15Yang L. Xiong Q. Li Y. et al.Artemisinin-passivated mixed-cation perovskite films for durable flexible perovskite solar cells with over 21% efficiency.J. Mater. Chem. 2021; 9: 1574-1582Crossref Google ScholarDue to their polycrystalline nature, perovskite films also suffer from the influence of strain on the optoelectronic properties and stability.16Liu D. Luo D. Iqbal A.N. et al.Strain analysis and engineering in halide perovskite photovoltaics.Nat. Mater. 2021; 20: 1337-1346Crossref PubMed Scopus (64) Google Scholar,17Cheng Y. Ding L. Pushing commercialization of perovskite solar cells by improving their intrinsic stability.Energy Environ. Sci. 2021; 14: 3233-3255Crossref Google Scholar The residual strain is related to the stability of the perovskite18Rolston N. Bush K.A. Printz A.D. et al.Engineering stress in perovskite solar cells to improve stability.Adv. Energy Mater. 2018; 8: 1802139Crossref Scopus (162) Google Scholar and usually accelerates its degradation by increasing ion migration and reducing perovskite structural stability.19Zhao J. Deng Y. Wei H. et al.Strained hybrid perovskite thin films and their impact on the intrinsic stability of perovskite solar cells.Sci. Adv. 2017; 3: eaao5616Crossref PubMed Scopus (413) Google Scholar The microstrain, which originates from local lattice mismatch or misorientation and is related to the local lattice disorder and defects,20Wu J. Liu S.-C. Li Z. et al.Strain in perovskite solar cells: origins, impacts and regulation.Natl. Sci. Rev. 2021; 8: nwab047Crossref PubMed Scopus (42) Google Scholar is highly detrimental to the perovskite film and thus urgently needs to be mitigated. Although modifying the perovskite lattice by cation doping, such as Cd2+21Saidaminov M.I. Kim J. Jain A. et al.Suppression of atomic vacancies via incorporation of isovalent small ions to increase the stability of halide perovskite solar cells in ambient air.Nat. Energy. 2018; 3: 648-654Crossref Scopus (387) Google Scholar and MDA2+,22Kim G. Min H. Lee K.S. et al.Impact of strain relaxation on performance of α-formamidinium lead iodide perovskite solar cells.Science. 2020; 370: 108-112Crossref PubMed Scopus (537) Google Scholar has been demonstrated to lower microstrain for efficient and stable PSCs, the strain related to environmental effects such as bending, which is extremely important for FPSCs, cannot be alleviated by the above-mentioned method.In this work, we judiciously designed a novel multifunctional additive, methylammonium succinate (MS), to alleviate strain and passivate interface defects in a perovskite film. It has been reported that FAI-terminated surfaces and PbI2-terminated surfaces are stable surfaces in FAPbI3 grains.23Oner S.M. Sezen E. Yordanli M.S. et al.Surface defect formation and passivation in formamidinium lead triiodide (FAPbI3) perovskite solar sell absorbers.J. Phys. Chem. Lett. 2022; 13: 324-330Crossref PubMed Scopus (6) Google Scholar The two terminal carboxyl groups in MS can form hydrogen bonds with with two perovskite the the two carboxyl groups to the strain by environmental effects such as thermal stress and bending of flexible devices, leading to perovskite films with reduced defects and In addition, the carboxyl can with the at the surface of perovskite and the can for the in the reducing the number of As a result, we achieved a high PCE of 25.4% and 23.6% (certified 22.5%) for rigid and flexible PSCs, which is the reported PCE for FPSCs to In addition, the with the perovskite grain the grain and the strain the bending the FPSCs exhibited bending durability, ∼85% of their initial efficiency after 10 000 bending a 6 mm