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Solvent additives are pivotal for enhancing the morphology, efficiency, and stability of organic solar cells (OSCs). However, the widely used additive, 1,8‐diiodooctane (DIO), has drawbacks like harmful halogen content and potential OSC degradation. To address these issues, novel non‐halogenated, thienyl‐alkyl‐thienyl structural solvent additives—DTP, DTH, and DTN—featuring varying alkyl linker lengths of (CH2)3, (CH2)6, and (CH2)9, respectively are introduced. Additives with longer alkyl linkers, DTH and DTN, effectively dissolve and strongly interact with both the donor polymer PM6 and acceptor L8‐BO. This dual interaction enables precise tuning of their microstructures, resulting in enhanced crystallinity. Upon incorporating DTH as an additive in OSCs (PM6:L8‐BO), a minimal voltage loss is observed, leading to an impressive efficiency of 18.51%, surpassing the 17.90% achieved with DIO. Furthermore, DTH‐based devices demonstrated superior photostability. In a ternary blend system (PM6:D18‐Cl:L8‐BO), an efficiency of 19.07% is attained, outperforming previous non‐halogenated solvent additive‐based OSCs. Furthermore, employing a non‐halogenated processing solvent combination of toluene and carbon disulfide, a high PCE of 18.82% is achieved. These results underscore the efficacy of designing solvent additives with aromatic and alkyl units, enabling tailored interactions with the donor and acceptor, thereby presenting a robust strategy for optimizing OSC performance and stability. [ABSTRACT FROM AUTHOR]

To understand the limitations placed on the open‐circuit voltage of bulk heterojunction (BHJ) organic solar cells, the energy levels of neat donor and acceptor samples are often characterized and applied to study BHJ blends. However, energy levels derived from neat samples may not necessarily reflect those at the donor:acceptor interface in blends. The properties of organic semiconductors are sensitive to microstructural changes, with non‐fullerene acceptors (NFAs) in particular known to exhibit different thin‐film polymorphs. To investigate the influence of differences in molecular packing in neat and blend films, temperature‐dependent current–voltage characteristics are measured for bilayer (BL) and BHJ devices. Herein, the fullerene acceptor PC71BM is compared—whose energy levels are expected to be less sensitive to molecular packing—with the NFA ITIC, paired with the same donor polymer PTB7‐Th. It is found that the interfacial energy levels differ for BL and BHJ devices for the PTB7‐Th:ITIC system but remain the same for the PTB7‐Th:PC71BM system. Furthermore, X‐ray scattering measurements identify that ITIC exhibits a different packing mode in neat films and in BHJ blends. Such microstructure‐dependent differences between neat and blend samples need to be considered when studying energy losses in NFA BHJ solar cells. [ABSTRACT FROM AUTHOR]

Doped organic semiconductors play a central role in the development of several innovative optoelectronic and energy harvesting applications. Currently, the realization of thermoelectric generators, which require both hole‐ and electron‐transporting materials with high electrical conductivity, is strongly hindered by the scarce availability of stable solution‐processable n‐dopants and their limited efficiency. Herein, the synthesis of 4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl)‐dibenzazepine (IStBI), a novel derivative belonging to the well‐known family of the benzimidazoline compounds, is presented. The functionalization with the planarized and rigid iminostilbene substituent allows, without significantly affecting the compound electronic structure, an efficient intercalation of the dopant molecules inside the ordered regions of thin films of the benchmark n‐type polymer poly(N,N′‐bis‐2‐octyldodecylnaphthalene‐1,4,5,8‐bis‐dicarboximide‐2,6‐diyl‐alt‐5,5′‐2,2′‐bithiophene) P(NDI2OD‐T2). Consequently, a maximum electrical conductivity of (1.14 ± 0.13) × 10−2 S cm−1 is recorded, exceeding by one order of magnitude what previously achieved upon solution doping of the reference P(NDI2OD‐T2) with benzimidazoline derivatives. The thermoelectric power factor is also simultaneously increased. The findings confirm that tailoring of the dopant chemical structure to improve structural interactions with the host semiconductors can be employed as a successful strategy to achieve more effective n‐doping, helping to close the performance gap with p‐type materials. [ABSTRACT FROM AUTHOR]

Herein, three double‐cable conjugated polymers are developed for indoor single‐component organic solar cells (SCOSCs). The new double‐cable conjugated polymers contain pendent nonfused electron acceptors with A‐π‐D‐π‐A configuration, in which group A uses 1H‐indene‐1,3(2H)‐dione (ID) as an electron‐withdrawing end group. The innovative design enables the double‐cable polymer to show absorption spectra in the range of 400–700 nm, which is matched with the spectra of indoor light‐emitting diode lights. In addition, the ID units at the acceptor side units and the introduction of halogen atoms make the double‐cable polymers show high photovoltage (>1.0 V) in SCOSCs. As a result, SCOSCs based on the new double‐cable polymers exhibit a high efficiency of 18% under indoor light illumination. The findings present a novel modular design approach for wide‐bandgap double‐cable conjugated polymers that can be utilized for indoor photovoltaics. [ABSTRACT FROM AUTHOR]

Double-cable conjugated polymers contain electron-donating (D) backbones and electron-accepting (A) side units, in which the nanophase separation of the donor and acceptor segments is a crucial factor to determine the photovoltaic performance of single-component organic solar cells (SCOSCs). In this work, three random double-cable conjugated polymers (denoted as P1–P3 with enhanced acceptor contents) have been designed to tailor the nanophase separation of D/A to realize high-performance SCOSCs. These new random double-cable conjugated polymers contain identical polymer backbones with varied contents of near-infrared acceptor side units. It is observed that the acceptor contents could effectively tune the aggregation degree of the backbone and acceptor (shown in the absorption spectra and grazing-incidence wide-angle X-ray scattering measurement) and further influence the construction of charge-transporting pathways. Therefore, a moderate content of acceptor side units provides balanced D/A aggregation and optimal nanophase separation, resulting in a high efficiency of 9.4% in SCOSCs. These results demonstrate that random double-cable conjugated polymers are an excellent model for studying the impact of their aggregation/crystallinity so as to realize high-performance SCOSCs. [ABSTRACT FROM AUTHOR]

The construction of high‐performance organic solar cells (OSCs) based on non‐fused ring electron acceptors (NFREAs) is challenging despite their low synthesis complexity and low cost. Herein, highly efficient NFREA‐based OSCs using a ternary approach by blending two in‐house designed NFREAs called "C6C4‐4Cl" and "BTIC‐4F" with the donor PM6 are demonstrated. The two NFREAs with similar molecular skeletons tend to form an alloy‐like phase that exhibits long exciton diffusion lengths and improved crystalline properties for efficient charge transfer. The complementary absorption spectra of the ternary system and energy transfer between the two NFREAs increases the current while the high lowest unoccupied molecular orbital (LUMO) energy level of BTIC‐4F enhances the voltage of the OSCs. As a result, the ternary OSC with two NFREAs yields an impressive power conversion efficiency (PCE) of 15.62% using 2PACz as a hole transporting layer (HTL). Investigation of the buried interface reveals that 2PACz has a strong interaction with PM6 and induces vertical phase separation in the ternary blend. This work provides an effective strategy to improve the performance of NFREA‐based OSCs by increasing the exciton diffusion length in an alloy‐like acceptor phase and inducing vertical phase separation with the judicious selection of HTL. [ABSTRACT FROM AUTHOR]

Improvement in the efficiency of organic photovoltaics (OPVs) is mainly attributed to non-fullerene acceptors (NFAs). However, NFAs exhibit an anisotropic chemical structure, resulting in over-sized aggregation, which can affect the exciton dissociation and charge transport. While the effect of different morphologies on the device performance has been observed in several studies, little is known about the composition and local molecular ordering in bulk heterojunction (BHJ) blend films of the polymer donor and NFAs. Here, we manipulate the morphology of blend films from large micron-sized phase-separated domains to fine-scale nano-domains via varying the drying kinetics of the film formation. We investigate the composition by micro-Raman spectroscopic studies of these blend films and visualize the molecular ordering at the sub-nanometer scale using a combination of cryo-electron microscopy and X-ray studies. Interestingly, we find that the molecules are oriented differently at the edge and at the center of these domains, a feature that has not been observed previously in spin-coated films containing NFAs. Moreover, we have extended our study to other donor-NFA systems and have observed a similar effect of drying kinetics on the microstructural and optical properties. Furthermore, our study shows that the change in the performance of the PTB7-Th:IEICO-4F device due to micron- and nano-sized morphology is relatively less, which is in contrast to a general notion of OPV systems. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) based on polymer donor and non‐fullerene acceptor achieve power conversion efficiency (PCE) more than 19% but their poor absorption below 550 nm restricts the harvesting of high‐energy photons. In contrast, wide bandgap all‐inorganic perovskites limit the absorption of low‐energy photons and cause serious below bandgap loss. Therefore, a 2‐terminal (2T) monolithic perovskite/organic tandem solar cell (TSC) incorporating wide bandgap CsPbI2Br is demonstrated as front cell absorber and organic PM6:Y6 blend as rear cell absorber, to extend the absorption of OSCs into high‐energy photon region. The perovskite sub‐cell, featuring a sol–gel prepared ZnO/SnO2 bilayer electron transporting layer, renders a high open‐circuit voltage (VOC). The VOC is further enhanced by employing thermal annealing (TA)‐free process in the fabrication of rear sub‐cell, demonstrating a record high VOC of 2.116 V. The TA‐free Ag/PFN‐Br interface in organic sub‐cell facilitates charge transport and restrains nonradiative recombination. Consequently, a remarkable PCE of 20.6% is achieved in monolithic 2T‐TSCs configuration, which is higher than that of both reported single junction and tandem OSCs, demonstrating that tandem with wide bandgap all‐inorganic perovskite is a promising strategy to improve the efficiency of OSCs. [ABSTRACT FROM AUTHOR]

Recent advances in organic solar cell performance have been mainly driven forward by combining high-performance p-type donor–acceptor copolymers (e.g.PM6) and non-fullerene small molecule acceptors (e.g.Y6) as bulk-heterojunction layers. A general observation in such devices is that the device performance, e.g., the open-circuit voltage, is strongly dependent on the processing solvent. While the morphology is a typically named key parameter, the energetics of donor–acceptor blends are equally important, but less straightforward to access in the active multicomponent layer. Here, we propose to use spectral onsets during electrochemical cycling in a systematic spectroelectrochemical study of blend films to access the redox behavior and the frontier orbital energy levels of the individual compounds. Our study reveals that the highest occupied molecular orbital offset (ΔEHOMO) in PM6:Y6 blends is ∼0.3 eV, which is comparable to the binding energy of Y6 excitons and therefore implies a nearly zero driving force for the dissociation of Y6 excitons. Switching the PM6 orientation in the blend films from face-on to edge-on in bulk has only a minor influence on the positions of the energy levels, but shows significant differences in the open circuit voltage of the device. We explain this phenomenon by the different interfacial molecular orientations, which are known to affect the non-radiative decay rate of the charge-transfer state. We compare our results to ultraviolet photoelectron spectroscopy data, which shows distinct differences in the HOMO offsets in the PM6:Y6 blend compared to neat films. This highlights the necessity to measure the energy levels of the individual compounds in device-relevant blend films. [ABSTRACT FROM AUTHOR]

Double‐cable conjugated polymers with near‐infrared (NIR) electron acceptors are synthesized for use in single‐component organic solar cells (SCOSCs). Through the development of a judicious synthetic pathway, the highly sensitive nature of the 2‐(3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (IC)‐based electron acceptors in basic and protonic solvents is overcome. In addition, an asymmetric design motif is adopted to optimize the packing of donor and acceptor segments, enhancing charge separation efficiency. As such, the new double‐cable polymers are successfully applied in SCOSCs, providing an efficiency of over 10 % with a broad photo response from 300 to 850 nm and exhibiting excellent thermal/light stability. These results demonstrate the powerful design of NIR‐acceptor‐based double‐cable polymers and will enable SCOSCs to enter a new stage. [ABSTRACT FROM AUTHOR]

Solar cells based on organic–inorganic hybrid perovskite materials have emerged as the most efficient next-generation thin-film solar cells within just a decade of research and show great promise for commercialization. As control of the thin-film microstructure of the perovskite layer is a key factor enabling high photovoltaic efficiency, good stability, and successful up-scaling of high-quality perovskite thin films for commercialization, a reliable and accurate characterization of the thin-film microstructure is paramount. X-ray diffraction (XRD)-based techniques, including conventional laboratory-based XRD and synchrotron-based grazing-incidence wide-angle x-ray scattering, are widely used to probe the microstructure of photovoltaic perovskite thin films. Nevertheless, it is common for these XRD experiments to be poorly executed and diffraction data to be improperly interpreted. This review focuses on principles of XRD techniques and their application for the characterization of the perovskite thin-film microstructure. Fundamentals of XRD techniques are presented with a strong emphasis on best practices in data collection and analysis. Approaches for the reliable and accurate extraction of microstructural information from diffraction data are discussed, including the need for simulating diffraction patterns. Applications of XRD techniques in characterizing perovskite thin films are demonstrated for both three-dimensional and layered hybrid perovskites, covering various microstructural aspects including phase identification and quantification, texture analysis, microstrain, and macrostrain as well as in situ and operando characterization. The additional subtleties and complexities associated with the XRD characterization of layered hybrid perovskites due to a more complex thin-film microstructure are discussed. Common mistakes and pitfalls that lead to misinterpretation of diffraction data are also highlighted. [ABSTRACT FROM AUTHOR]

Bulk heterojunction organic solar cells continue to show steady photoconversion efficiency improvements. However, single component organic solar cells are a particularly attractive alternative due to the relative simplicity of device manufacture. It has been proposed that organic semiconductors with a high dielectric constant (≈10) could give rise to spontaneous free charge carrier generation upon photoexcitation. In this manuscript, factors are explored that affect the dielectric constant of organic semiconductors, particularly the optical‐frequency dielectric constant. The properties of monomers, dimers and trimers of two isoelectronic families of materials that have acceptor units composed of one or two dicyanovinylbenzothiadiazole moieties and one to three donor units are compared. The donor components are composed of either fluorenyl or cyclopentadithiophene moieties with the same glycol‐based solubilizing groups. It is found that chromophore planarity and orientation with respect to the substrate, and film density affect the optical and electronic properties of the materials, especially the high‐frequency dielectric constant. The results also indicate that delocalization of the highest occupied and lowest unoccupied molecular orbitals is a critical factor. The dimer with two dicyanovinylbenzothiadiazole moieties and two dithienocyclopentadiene units is found to have the highest optical frequency dielectric constant and overall performance. [ABSTRACT FROM AUTHOR]

Atom-economic protocols for the synthesis of poly(indacenodithiophene-alt-benzothiadiazole) (PIDTBT) are presented in which all C–C coupling steps are achieved by direct arylation. Using two different synthetic pathways, PIDTBT copolymers with different side chains (hexylphenyl, octylphenyl, dodecyl, methyl/2-octyldodecylphenyl, 2-octyldodecylphenyl/2-octyldodecylphenyl) and molecular weight (MW) are prepared. Route A makes use of direct arylation polycondensation (DAP) of indacenodithiophene (IDT) and 4,7-dibromo-2,1,3-benzothiadiazole (BTBr2) leading to PIDTBT in high yields, with adjustable MW and without indications for structural defects. Route B starts from a polyketone precursor also prepared by DAP following cyclization. While route B allows introduction of asymmetric side chains at the IDT unit, polymer analogous cyclization gives rise to defect formation. The absorption coefficient of PIDTBT with alkylphenyl side chains made by route A increases with MW. Field-effect hole mobilities around ∼10−2 cm2 V−1 s−1 are molecular weight-independent, which is ascribed to a largely amorphous thin film morphology. PIDTBT with linear dodecyl side (C12) chains exhibits a bathochromic shift (20 nm), in agreement with theory, and more pronounced vibronic contributions to absorption spectra. In comparison to alkylphenyl side chains, C12 side chains allow for increased order in thin films, a weak melting endotherm and lower energetic disorder, which altogether explain substantially higher field-effect hole mobilities of ∼ 10−1 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Ruddlesden–Popper layered perovskites have emerged as a promising solution for overcoming the moisture instability of three-dimensional hybrid perovskite materials. Given that the optoelectronic properties of these layered perovskites strongly depend on the dimensionality (n) of the phases present, understanding of the microstructure and order in such materials is important. Typically, the dimensionality of phases present is inferred from optical measurements rather than diffraction measurements which are a more direct probe of structural order. Here we use a combination of grazing-incidence transmission wide-angle X-ray scattering and transmission wide-angle X-ray scattering techniques to probe the in-plane microstructure of highly textured Ruddlesden–Popper hybrid perovskite films with a target dimensionality of n = 4. By being able to resolve the in-plane diffraction peaks corresponding to the periodic repeating of layered phases that are often obscured by the substrate horizon in grazing incidence measurements, we are able to directly characterise structural order in such films. Despite having a target dimensionality of n = 4, only diffraction peaks corresponding to n = 2, 3 and ∞ phases are observed. Observations from X-ray measurements are combined with optical absorption measurements to show that there is increasing structural disorder in low-n phases with increasing dimensionality. Further analysis of peak positions and peak widths in the X-ray scattering patterns indicate that stacking fault defects are the origin of structural disorder in layered perovskite films, with increasing disorder with increasing n. We also present a complete indexing of grazing-incidence wide-angle X-ray scattering patterns of highly textured layered perovskite films and confirm the structurally ordered n = 3 and ∞ phases as the dominant crystalline phases in such films. This work provides guidance for the reliable characterisation of structural order and orientation in layered perovskite thin films from X-ray scattering measurements which will assist with assessing n-phase purity and photovoltaic device optimisation. [ABSTRACT FROM AUTHOR]

Background: The Scn3b gene encodes for Navβ3, a pivotal regulatory subunit of the fast sodium channel in cardiomyocytes. However, its mutation status in the Chinese population suffering from Brugada Syndrome (BrS) has not been characterized, and the contributory pathophysiological mechanisms to disease pathology remain undefined., Methods and Results: A Scn3b (c.260C>T, p.P87l) mutation was identified in a patient with BrS of Chinese descent. Functional analyses demonstrated that sodium channel activation for the wild type, mutant samples, and co-expression of both commenced at -55 mv and peaked at -25 mv. The mutant group exhibited a notable reduction, approximately 60%, in peak sodium channel activation current (I Na ) at -25 mv. The parameters for half-maximal activation voltages (V 1/2 ) and slope factors (k) showed no significant differences when comparing wild type, mutant, and combined expression groups ( P  = 0.98 and P  = 0.65, respectively). Additionally, no significant disparities were evident in terms of the steady-state sodium channel inactivation parameters V 1/2 and k (with P -values of 0.85 and 0.25, respectively), nor were there significant differences in the activation time constant τ ( P  = 0.59) and late sodium current density ( P  = 0.23) across the wild-type, mutant, and co-expressed groups. Confocal imaging and Western blot analysis demonstrated decreased plasma membrane localization of SCN3B and SCN5A in the P87l group. Computational simulations of cardiac action potentials suggested that SCN3B P87l can alter the morphology of the action potentials within the endocardium and epicardium while reducing the peak of depolarization., Conclusions: The pathogenic impact of the Scn3b P87l mutation predominantly originates from a reduction in peak I Na activation current coupled with decreased cell surface expression of Nav1.5 and Navβ3. These alterations may influence cardiac action potential configurations and contribute to the risk of ventricular arrhythmias in individuals with BrS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Fan, Wang, Cao, Li, Sun, Luo, Pan, Tan, Wu, Liu and Yu.)

The dramatic improvement of the PCE (power conversion efficiency) of organic photovoltaic devices in the past few years has been driven by the development of new polymer donor materials and non-fullerene acceptors (NFAs). In the design of such materials synthetic scalability is often not considered, and hence complicated synthetic protocols are typical for high-performing materials. Here we report an approach to readily introduce a variety of solubilizing groups into a benzo[ c ][1,2,5]thiadiazole acceptor comonomer. This allowed for the ready preparation of a library of eleven donor polymers of varying side chains and comonomers, which facilitated a rapid screening of properties and photovoltaic device performance. Donor FO6-T emerged as the optimal material, exhibiting good solubility in chlorinated and non-chlorinated solvents and achieving 15.4% PCE with L8BO as the acceptor (15.2% with Y6) and good device stability. FO6-T was readily prepared on the gram scale, and synthetic complexity (SC) analysis highlighted FO6-T as an attractive donor polymer for potential large scale applications.

Background and Aims: Despite the remarkable progress of metabolic dysfunction-associated fatty liver disease (MAFLD), formerly named non-alcoholic fatty liver disease (NAFLD), the disease remains poorly improved. Since increased oxidative stress and inflammation contribute to the initiation and progression of fatty liver disorders, vitamin C (VC), an antioxidant agent, might be a suitable treatment option for MAFLD. However, the lack of clinically confirmed benefits makes clinicians challenging to recommend antioxidant supplements for MAFLD individuals., Methods: Herein, the nationally representative National Health and Nutrition Examination Survey 2017-2018 data were collected to evaluate the potential association between the serum VC levels with the risk of different categories of NALFD and the newly proposed MAFLD terminology. Hepatic steatosis was defined as controlled attenuated parameter scores ≥ 263 dB/m, whereas liver fibrosis (LF) status was defined as F0-F4, with the cutoff values of median liver stiffness being 6.3, 8.3, 10.5, and 12.5 (KPa), respectively. A cross-sectional analysis was performed to calculate the odds rate and determine the potential beneficial effects of VC., Results: A total of 4,494 participants aged more than 18 years and conducted transient elastography examinations were included. Our findings demonstrated that participants with increased serum VC status were more likely to be female predominant, more educated, and moderate drinkers. Interestingly, female participants tended to have a lower prevalence of NAFLD, MAFLD, LF, and liver cirrhosis (LC) after stratification by gender. Moreover, our results revealed that participants from the quartile three group (quartile 3: 50.5-67.0 μmol/L) experienced a slightly lower risk of MAFLD than the risk of NAFLD. Of note, the serum concentration of VC (quartile 2: 30.9-50.5 μmol/L) inversely associated with LF and LC was lower than the serum VC level (quartile 3) associated with NAFLD and MAFLD. Notably, individuals from the quartile 3 group experienced a statistically significant 32.5, 42.0, 45.7, and 71% decrease in risk of NAFLD, MAFLD, LF, and LC, respectively., Conclusion: In summary, our findings suggested an inverse association between serum VC levels and NAFLD, MAFLD, LF, or LC. Additionally, adjustment of VC supplementation according to age, gender, and ethnicity may be a promising candidate for these diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Xie, Li, Tan, Yang, Ma, Li, Wang, Shang and Chen.)

Background and Aims: Cholecystectomy is the "gold standard" for treating diseases of the gallbladder. In addition, non-alcoholic fatty liver disease (NAFLD), liver fibrosis or cirrhosis, are major causes of morbidity and mortality across the world. However, the association between cholecystectomy and these diseases is still unclear. We assessed the association among US adults and examined the possible risk factors. Methods: This cross-sectional study used data from 2017 to 2018 National Health and Nutrition Examination Survey, a population-based nationally representative sample of US. Liver fibrosis and cirrhosis were defined by median stiffness, which was assessed by transient elastography. Furthermore, patients who had undergone cholecystectomy were identified based on the questionnaire. In addition, Propensity Score Matching (PSM, 1:1) was performed based on gender, age, body mass index (BMI) and diabetes. Results: Of the 4,497 included participants, cholecystectomy was associated with 60.0% higher risk of liver fibrosis (OR:1.600;95% CI:1.278-2.002), and 73.3% higher risk of liver cirrhosis (OR:1.733, 95% CI:1.076-2.792). After PSM based on age, gender, BMI group and history of diabetes, cholecystectomy was associated with 139.3% higher risk of liver fibrosis (OR: 2.393;95% CI: 1.738-3.297), and 228.7% higher risk of liver cirrhosis (OR: 3.287, 95% CI: 1.496-7.218). Conclusions: The present study showed that cholecystectomy is positively associated with liver fibrosis and cirrhosis in US adults. The discovery of these risk factors therefore provides new insights on the prevention of NAFLD, liver fibrosis, and cirrhosis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Xie, Li, Tan, Yang, Ma, Li, Wang, Shang and Chen.)

3D/2D hybrid perovskite systems have been intensively investigated to improve the stability of perovskite solar cells (PSCs), whereas undesired crystallization of 2D perovskite during the film formation process could undermine the structural stability of 2D perovskite materials, which causes serious hysteresis of PSCs after aging. This issue is, however, rarely studied. The stability study for 3D/2D hybrid systems to date is all under the one-direction scan, and the lack of detailed information on the hysteresis after aging compromises the credibility of the stability results. In this work, by correlating the hysteresis of the hybrid PSCs with the 2D crystal structure, we find that the prompt 2D perovskite formation process easily induces numerous crystal imperfections and structural defects. These defects are susceptible to humidity attack and decompose the 2D perovskite to insulating long-chain cations and 3D perovskite, which hinder charge transfer or generate charge accumulation. Therefore, a large hysteresis is exhibited after aging the 3D/2D hybrid PSCs in an ambient environment, even though the reverse-scan power conversion efficiency (PCE) is found to be well-preserved. To address this issue, alkali cations, K + and Rb + , are introduced into the 2D perovskite to exquisitely modulate the crystal formation, which gives rise to a higher crystallinity of 2D perovskite and a better film morphology with fewer defects. We achieved PCE beyond 21% due to the preferable charge transfer process and reduced nonradiative recombination losses. The structural features also bring about impressive moisture stability, which results in the corresponding PSCs retaining 93% of its initial PCE and negligible hysteresis after aging in an ambient atmosphere for 1200 h.