Centimeter-Sized Single Crystals of Two-Dimensional Hybrid Iodide Double Perovskite (4,4-Difluoropiperidinium)4AgBiI8 for High-Temperature Ferroelectricity and Efficient X-Ray Detection

Ferroelectricity and X-ray detection property have been recently implemented for the first time in hybrid bromide double perovskites. It sheds a light on achieving photosensitive and ferroelectric multifunctional materials based on 2D lead-free hybrid halide double perovskites. However, the low T_c, small P_s, and relatively low X-ray sensitivity in the reported bromide double perovskites hinder practical applications. Herein, the authors demonstrate a novel 2D lead-free iodide double perovskite (4,4-difluoropiperidinium)₄AgBiI₈ (1) for high-performance X-ray sensitive ferroelectric devices. Centimeter-sized single crystal of 1 is obtained and exhibits an excellent ferroelectricity including a high T_c up to 422 K and a large P_s of 10.5 μC cm⁻². Moreover, due to a large X-ray attenuation and efficient charge carrier mobility (μ)–charge carrier lifetime (τ) product, the crystal 1 also exhibits promising X-ray response with a high sensitivity up to 188 μC·Gy_air⁻¹ cm⁻² and a detection limit below 3.13 μGy_air·s⁻¹. Therefore, this finding is a step further toward practical applications of lead-free halide perovskite in high-performance photoelectronic devices. It will afford a promising platform for exploring novel photosensitive ferroelectric multifunctional materials based on lead-free double perovskites.     

Centimeter-Sized Molecular Perovskite Crystal for Efficient X-Ray Detection

Molecular perovskites have demonstrated great potential for ferroelectrics and nonlinear optics; however, their charge transport properties for optoelectronics have rarely been explored. Here, understanding of charge transport behavior of molecular perovskite under X-ray excitation based on centimeter-scale TMCM-CdCl₃ (TMCM⁺, trimethylchloromethyl ammonium) single crystal is demonstrated. The crystal is fabricated from an aqueous solution and exhibits a large bandgap of 5.51 eV, with the valence band maximum mainly dominated by the Cl-p/Cd-d states and the conduction band minimum primarily by Cd-s/Cl-p states. Charge mobility exceeding 40 cm² V⁻¹ s⁻¹ and mobility–lifetime (µτ) product on the order of 10⁻⁴ cm² V⁻¹ for the crystal are observed. These excellent optoelectronic properties translate to an efficient photoresponse under X-ray excitation, with the sensitivity reaching 128.9 ± 4.64 µC Gy_air⁻¹ cm⁻² [fivefold higher than that of the commercialized amorphous selenium (α-Se)] and a low detection limit of 1.06 μC Gy_air⁻¹ s⁻¹ (10 V bias). This work pioneers a superior metal-based molecular perovskite single-crystal based paradigm for optoelectronic investigation, which may lead to the discovery of a new generation of X-ray detection and imaging materials.     

Experimental Strategy and Mechanistic View to Boost the Photocatalytic Activity of Cs3Bi2Br9 Lead-Free Perovskite Derivative by g-C3N4 Composite Engineering

The rational design of heterojunctions based on metal halide perovskites (MHPs) is an effective route to create novel photocatalysts to run relevant solar-driven reactions. In this work, an experimental and computational study on the synergic coupling between a lead-free Cs₃Bi₂Br₉ perovskite derivative and g-C₃N₄ is presented. A relevant boost of the hydrogen photogeneration by more than one order of magnitude is recorded when going from pure g-C₃N₄ to the Cs₃Bi₂Br₉/g-C₃N₄ system. Effective catalytic activity is also achieved in the degradation of the organic pollutant with methylene blue as a model molecule. Based upon complementary experimental outputs and advanced computational modeling, a rationale is provided to understand the heterojunction functionality as well as the trend of hydrogen production as a function of perovskite loading. This work adds further solid evidence for the possible application of MHPs in photocatalysis, which is emerging as an extremely appealing and promising field of application of these superior semiconductors.     

Silver Ions Assisted Inversion Temperature Crystallization of 2D Cs3Bi2Br9 Nanoflakes for Highly Sensitive X-Ray Detection

2D perovskites have attracted wide attention for optoelectronic applications because of their unique layer structure and tunable outstanding optical/electrical properties. In addition, 2D Cs₃Bi₂Br₉ nanoflakes possess large effective atomic number, high resistivity, high density as well as excellent stability, rendering it a promising material for X-ray detection. Nevertheless, it is full of challenges to synthesize 2D Cs₃Bi₂Br₉ nanoflakes by conventional inversion temperature crystallization (ITC) strategy due to the existence of Br^- vacancies in the Cs₃Bi₂Br₉ crystal nucleus. Herein, an Ag⁺ assisted ITC (SAITC) strategy to grow 2D Cs₃Bi₂Br₉ nanoflakes is proposed. The synthesis mechanism revealed by both experiments and theoretical calculations can be mainly ascribed to the passivated Br⁻ vacancies and enhanced structure stability by adding Ag⁺ which can effectively prevent the oxidation of 2D Cs₃Bi₂Br₉ nanoflakes from growth of hybrid crystals. The synthesized high-crystallinity 2D Cs₃Bi₂Br₉ nanoflakes possess direct bandgap characteristic, and the mobility lifetime can reach 9.8 × 10⁻⁴ cm² V⁻¹. Excitingly, the fabricated device based on 2D Cs₃Bi₂Br₉ nanoflakes demonstrates ultrahigh sensitivity of detecting X-ray (1.9 CGy_air⁻¹cm⁻²) at very low driven voltage (0.5 V) due to the photoconductive gain mechanism. The 2D Cs₃Bi₂Br₉ nanoflakes synthesized by SAITC method have great potential for developing highly sensitive optoelectronic devices.     

Strong Self-Trapped Exciton Emission and Highly Efficient Near-Infrared luminescence in Sb3+-Yb3+ Co-doped Cs2AgInCl6 Double Perovskite

Yb³⁺ doped lead-free double perovskites (DPs) with near-infrared (NIR)-emitting have attracted extensive attention due to their wide application prospects. Unfortunately, they still suffer from weak NIR emission due to undesirable resonance energy transfer between the sensitizers and Yb³⁺ ions. Herein, a new effective NIR-emitting DP is developed by co-doping Sb³⁺ and Yb³⁺ into Cs₂AgInCl₆. Experiments and theoretical calculations reveal that induced by co-doping Sb³⁺ ions, the self-trapped excitation (STE) emission intensity of Cs₂AgInCl₆ is greatly enhanced by 240 times, and the STE emission shifts from 600 nm to 660 nm, which contributes to a larger spectral overlap between STE emission and the absorption of Yb³⁺ ions. As a result, the absolute NIR photoluminescence quantum yield reaches an unprecedented 50% in lead-free DPs via high-efficiency STE sensitization (>30%). The excellent optical performance of Cs₂AgInCl₆: Sb, Yb with high ambient, thermal and light stability makes it suitable for application in night-vision devices. Moreover, an ingenious dual-modal optical information encryption based on the combination of visible and NIR fluorescence printing patterns utilizing Cs₂AgInCl₆: Sb and Cs₂AgInCl₆: Sb, Yb respectively is successfully demonstrated. This study provides inspiration for designing highly efficient NIR-emitting Ln³⁺-doped DPs and illustrates their great potential in versatile optoelectronic applications.     

Inch-Size Single Crystals of Lead-Free Chiral Perovskites with Bulk Photovoltaic Effect for Stable Self-Driven X-Ray Detection

Lead halide perovskites have made great advance in direct X-ray detection, however the presence of toxic lead and the requirement of high working voltages severely limit their applicability and operational stability. Thus, exploring “green” lead-free hybrid perovskites capable of detecting X-rays at zero bias is crucial but remains toughly challenging. Here, utilizing chiral R/S-1-phenylpropylamine (R/S-PPA) cations, a pair of 0D chiral-polar perovskites, (R/S-PPA)₂BiI₅ ( 1 R / 1 S ) are constructed. Their intrinsic spontaneous electric polarization induces a large bulk photovoltage of 0.63 V, which acts as a driving force to separate and transport photogenerated carriers, thus endowing them with the capability of self-driven detection. Consequently, self-driven X-ray detectors with a low detection limit of 270 nGy s⁻¹ are successfully constructed based on high-quality, inch-sized single crystals of 1 R . Notably, they show suppressed baseline drift under the self-driven mode, exhibiting superior operational stability. This study realizes self-driven X-ray detection in a single-phase lead-free hybrid perovskite by exploiting the intrinsic bulk photovoltaic effect, which sheds light on future explorations of lead-free hybrid perovskites toward “green” self-driven radiation detectors with high performance.     

Air-Stable Self-Powered Photodetectors Based on Lead-Free CsBi3I10/SnO2 Heterojunction for Weak Light Detection

Lead halide perovskites (LHPs) have been widely investigated in photodetection applications owing to their intriguing optoelectronic properties. However, the application of LHPs-based photodetectors (PDs) is hindered because of the toxicity of lead and instability in ambient air. Here, an air-stable self-powered photodetector is designed based on all-inorganic lead-free CsBi₃I₁₀/SnO₂ heterojunction. The device exhibits broad spectral response in both UV and visible light, fast response on µs scale, and decent long-term stability. The device holds a faster response speed (t_r/t_d = 7.8/8.8 µs), among the best reported self-powered lead-free perovskites photodetectors. More importantly, the device can display obvious photoresponses even under ultra-weak light intensity as low as 10 pW cm^–2, showing better weak-light sensitivity than previously reported lead-free perovskites photodetectors, to the best of our knowledge. Moreover, the device holds good air stability in the 73 days test without encapsulation. These results suggest that CsBi₃I₁₀/SnO₂-based self-powered PDs with high photodetection capability possess enormous potential in stable and broadband PDs for weak light detection in the future.     

Composition-Dependent Photoluminescence Properties and Anti-Counterfeiting Applications of A2AgX3 (A = Rb,Cs; X = Cl,Br, I)

Copper(I) halides are emerging as attractive alternatives to lead halide perovskites for optical and electronic applications. However, blue-emitting all-inorganic copper(I) halides suffer from poor stability and lack of tunability of their photoluminescence (PL) properties. Here, the preparation of silver(I) halides A₂AgX₃ (A = Rb, Cs; X = Cl, Br, I) through solid-state synthesis is reported. In contrast to the Cu(I) analogs, A₂AgX₃ are broad-band emitters sensitive to A and X site substitutions. First-principle calculations show that defect-bound excitons are responsible for the observed main PL peaks in Rb₂AgX₃ and that self-trapped excitons (STEs) contribute to a minor PL peak in Rb₂AgBr₃. This is in sharp contrast to Rb₂CuX₃, in which the PL is dominated by the emission by STEs. Moreover, the replacement of Cu(I) with Ag(I) in A₂AgX₃ significantly improves photostability and stability in the air under ambient conditions, which enables their consideration for practical applications. Thus, luminescent inks based on A₂AgX₃ are prepared and successfully used in anti-counterfeiting applications. The excellent light emission properties, significantly improved stability, simple preparation method, and tunable light emission properties demonstrated by A₂AgX₃ suggest that silver(I) halides may be attractive alternatives to toxic lead halide perovskites and unstable copper(I) halides for optical applications.     

Discovering New Type of Lead-Free Cluster-Based Hybrid Double Perovskite Derivatives with Chiral Optical Activities and Low X-Ray Detection Limit

2D chiral hybrid perovskites have recently emerged as outstanding semiconductor materials. However, most of the reported 2D chiral perovskites have limited structural types and contain high levels of toxic lead, which severely hinders their further applications. Herein, by using a mixed-cation strategy, an unprecedented type of lead-free cluster-based 2D chiral hybrid double perovskite derivatives are successfully obtained, [(R/S-PPA)₄(IPA)₆Ag₂Bi₄I₂₄]·2H₂O ( 1-R and 1-S ), and [(R/S-PPA)₄(n-BA)₆Ag₂Bi₄I₂₄]·2H₂O ( 2-R and 2-S ) (R/S-PPA=R/S–1-phenylpropylamine; IPA=isopentylamine; n-BA=n-butylamine). Their inorganic skeletons are linked by binuclear {Bi₂I₁₀} and infinite chain {Ag₂Bi₂I₁₄}_∞, in which bismuth clusters and multiple coordination modes (e.g., tetrahedral AgI₄ and octahedral AgI₆) are introduced into the double perovskite system for the first time. This introduction induces distortion of the inorganic layer, which may facilitate the transfer of chirality from the chiral cations into achiral double perovskite skeletons. Further, circular dichroism measurements and circularly polarized light detection confirm their inherent chiral optical activities. In addition, 1-S exhibits an ultralow X-ray detection limit of 129.5 nGy s⁻¹, which is 42-fold lower than that of demands in regular medical diagnosis (5.5 µGy s⁻¹). This study provides a pathway to construct novel type of lead-free cluster-based double perovskite derivatives.     

Synergy of Organic and Inorganic Sites in 2D Perovskite for Fast Neutron and X-Ray Imaging

Fast neutron and X-ray imaging are considered complementary nondestructive detection technologies. However, due to their opposite cross-sections, development of a scintillator that is sensitive to both fast neutrons and X-rays within a single-material framework remains challenging. Herein, an organic–inorganic hybrid perovskite (C₄H₉NH₃)₂PbBr₄ (BPB) is demonstrated as a scintillator that fully meets the requirements for both fast neutron and X-ray detection. The hydrogen-rich organic component acts as a fast neutron converter and produces detectable recoil protons. The heavy atom-rich inorganic fraction efficiently deposits the energy of charged recoil protons and directly provides a large X-ray cross-section. Due to the synergy of these organic and inorganic components, the BPB scintillator exhibits high light yields (86% of the brightness of a commercial ZnS (Ag)/⁶LiF scintillator for fast neutrons; 22 000 photons per MeV for X-rays) and fast response times (τ_decay = 10.3 ns). More importantly, energy-selective fast neutron and X-ray imaging are also demonstrated, with high resolutions of ≈1 lp mm⁻¹ for fast neutrons and 17.3 lp mm⁻¹ for X-rays; these are among the highest resolution levels for 2D perovskite scintillators. This study highlights the potential of 2D perovskite materials for use in combined fast neutron and X-ray imaging applications.     

Enhanced Photocatalytic Activity of Lead-Free Cs2TeBr6/g-C3N4 Heterojunction Photocatalyst and Its Mechanism

In this study, a new type of lead-free double perovskite Cs₂TeBr₆ combined with metal-free semiconductor g-C₃N₄ heterojunction is constructed and used for photocatalytic CO₂ reduction for the first time. The S-scheme charge transfer mechanism between Cs₂TeBr₆ and g-C₃N₄ is systematically verified by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and in situ Fourier infrared spectroscopy(FT-IR). The formation of S-type heterojunction makes the photocatalyst have higher charge separation ability and highest redox ability. The results show that 5%-CTB/CN heterojunction material has the best photocatalytic reduction effect on CO₂ under visible light irradiation. After 3 h of illumination, the yield of CO and CH₄ are 468.9 µmol g⁻¹ and 61.31 µmol g⁻¹, respectively. The yield of CO is 1.5 times and 32 times that of pure Cs₂TeBr₆ and g-C₃N₄, and the yield of CH₄ is doubled compared with pure Cs₂TeBr₆. However, g-C₃N₄ almost does not produce CH₄, which indicates that the construction of heterojunction helps to further improve the photocatalytic performance of the material. This study provides a new idea for the preparation of Cs₂TeBr₆/g-C₃N₄ heterojunction and its effective interfacial charge separation.     

Lead-Free Double Perovskite Cs2AgBiBr6: Fundamentals,Applications, and Perspectives

Cs₂AgBiBr₆, as a benchmark lead-free double perovskite, has emerged as a promising alternative to lead-based perovskites because of its high stability, non-toxicity, exceptional optoelectronic properties, and multifunctionality. To encourage further research on Cs₂AgBiBr₆ and its broad applications, in this review, its fundamental properties including the structure-property relation, synthesis, stability, origin of absorption and photoluminescence, electron-phonon coupling, role of defects, charge carrier dynamics, and bandgap modulation are comprehensively emphasized. The recent progress on the wide applications including solar cells, light/X-ray detectors, and ferroelectric/magnetic devices are highlighted. Moreover, the challenges of Cs₂AgBiBr₆ materials and related applications are discussed and perspectives are provided for guiding the future development of this research area.     

Mixed Halide Formation in Lead-Free Antimony-Based Halide Perovskite for Boosted CO2 Photoreduction: Beyond Band Gap Tuning

Photocatalytic conversion of carbon dioxide (CO₂) into value-added fuels is a vastly promising anthropogenic chemical carbon cycle to combat the greenhouse effect while meeting the ever-increasing energy demand. Recently, lead-based halide perovskites have demonstrated great potential in various applications including photochemical reduction of CO₂. However, in view of lead toxicity, the exploration of a lead-free alternative is crucial for long term application. Herein, a series of lead-free mixed halide perovskites Cs₃Sb₂Cl_xBr_9−x (0 ≤ x ≤ 9) is prepared via a facile antisolvent recrystallization technique, where the incorporation of a secondary halide enhances the charge transfer and separation while allowing precise tuning of bandgap between 2.59 and 2.90 eV. Theoretical calculations further reveal that the formation of mixed Cl/Br halides engenders favorable charge redistribution due to lower octahedral distortion, which in turn strengthens CO₂ adsorption and activation. Under visible light illumination, the optimal dual halide perovskite, Cs₃Sb₂Cl₄Br₅ manifests substantial twofold and fourfold enhancements of CH₄ yield over the single halide perovskite, Cs₃Sb₂Br₉ and Cs₃Sb₂Cl₉, respectively. In brief, this study provides a compelling demonstration of lead-free mixed halide perovskites for photocatalytic CO₂ reduction, and it is anticipated to drive further application of perovskite-based photocatalysts toward a diverse range of artificial photoredox reactions.     

3D/2D Perovskite Single Crystals Heterojunction for Suppressed Ions Migration in Hard X-Ray Detection

Halide perovskites exhibit diverse properties depending on their compositions. However, integrating desired properties into one material is still challenging. Here, a facile solution-processed epitaxial growth method to grow 2D perovskite single crystal on top of 3D perovskite single crystal, which can passivate the surface defects for improved device performance is reported. Short formamidine (FA⁺) ions are replaced by long organic cations, which can fully align and cover the single crystal surface to prevent the ions migration or short FA⁺ ions volatilization. The thickness of epitaxial layer can be finely adjusted by controlling the growth time. The defect density of single crystals heterojunction is only 3.18 × 10⁹ cm⁻³, and the carrier mobility is 80.43 cm² V⁻¹ s⁻¹, which is greater than that of the control 3D perovskite single crystal. This study for the first time realized large area 3D/2D perovskite single crystals heterojunction, which suppressed ions migration and exhibited advanced performance in hard X-rays detection applications. This strategy also provides a way to grow large area 2D perovskite single crystal from solution processes.     

Bi1/2(Na1-xLix)1/2TiO3压电陶瓷的性能和微结构

利用传统陶瓷工艺制备了Bi1/2(Na1-xLix)1/2TiO3(简写BNLT100x,其中x为摩尔含量)系无铅压电陶瓷,研究了该陶瓷的微结构、压电和介电性能。X-射线衍射分析(XRD)结果表明,在x=0~0.20时,Bi1/2(Na1-xLix)1/2TiO3陶瓷为单相三方晶系钙钛矿结构;在x=0.30时,会有影响压电性能的第二相产生。扫描电镜(SEM)结果表明,Li含量越高,陶瓷的烧结温度越低,Li促进了晶粒特定方向的生长;在x=0.15时,压电系数d33达极大值109 pC/N;同时研究了极化工艺条件对材料压电性能的影响。     

Broadband Defects Emission and Enhanced Ligand Raman Scattering in 0D Cs3Bi2I9 Colloidal Nanocrystals

Excitonic 0D and 2D lead‐halide perovskites have been recently developed and investigated as new materials for light generation. Here broadband (>1 eV) emission from newly synthesized 0D lead‐free colloidal Cs₃Bi₂I₉ nanocrystals (NCs) is reported. The nature of their emissive states as well as the relative dynamics which are currently hotly debated are investigated. In particular, it is found that the broadband emission is made by the coexistence of emissive excitons and sub‐bandgap emissive trap‐states. Remarkably, evidence of enhanced Raman scattering from the ligands is observed when attached to the NCs surface, an effect that is preliminarily attributed to strong exciton‐ligands electronic coupling in these systems.     

Understanding the Role of Grain Boundaries on Charge-Carrier and Ion Transport in Cs2AgBiBr6 Thin Films

Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air, and recent demonstrations of long charge-carrier lifetimes that can exceed 1 µs. In particular, Cs₂AgBiBr₆ is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs₂AgBiBr₆ thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field-effect transistor and temperature-dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs₂AgBiBr₆ single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single-crystal properties.     

2D Hybrid Perovskite Ferroelectric Enables Highly Sensitive X‐Ray Detection with Low Driving Voltage

X‐ray detectors with high sensitivity are of great significance in both civil and military fields. Over the past decades, great efforts have been made to improve the sensitivity in conventional inorganic materials, but mainly at the cost of increasing the energy consumption with a quite high operating voltage. Developing photosensitive ferroelectrics directly as detector materials may be a conceptually new strategy in view of the strong ferroelectric spontaneous polarization (P_s) that assists photoinduced carriers separation and transport. A high‐performance X‐ray detector in 2D hybrid halide perovskite ferroelectric (C₄H₉NH₃)₂(C₂H₅NH₃)₂Pb₃Br₁₀ ( BA₂EA₂Pb₃Br₁₀ ) (P_s = 5 µC cm^?2) is fabricated and exhibits an ultrahigh X‐ray sensitivity up to 6.8 × 10³ µC Gy_air^?1 cm^?2 even at a relatively low operating voltage, which is over 300‐fold larger than that of state‐of‐the‐art α‐Se X‐ray detectors. Such a brilliant figure‐of‐merit is largely attributed to the superior mobility–lifetime products associated with the strong ferroelectric polarization of BA₂EA₂Pb₃Br₁₀ . As pioneering work, these findings inform the exploration of hybrid halide perovskite ferroelectrics toward high‐performance photoelectronic devices.     

Enhanced On–Off Ratio Photodetectors Based on Lead‐Free Cs3Bi2I9 Single Crystal Thin Films

Hybrid organic–inorganic lead halide perovskite single crystal thin film (SCTF) recently has attracted enormous interest in the field of optoelectronic devices, since it efficiently resolves the trade‐off between thickness and carrier diffusion length. However, the toxicity of lead element and the instability induced by organic component still hinder its future developments. In this work, lead‐free all‐inorganic Cs₃Bi₂I₉ SCTF with a high orientation along (00h) has been in situ grown on indium tin oxide (ITO) glass via a space‐limited solvent evaporation crystallization method. The trap density of Cs₃Bi₂I₉ SCTF (5.7 × 10¹² cm^?3) is 263 folds lower than that of the polycrystalline thin film (PCTF) counterpart, together with a 5‐order‐of‐magnitude higher carrier mobility. These superior charge transfer properties enable a photoresponse on–off ratio as high as 11 000, which far surpasses that of the PCTF device by 460 folds, comparable to the lead halide perovskite. Furthermore, the Cs₃Bi₂I₉ SCTF photodetector exhibits outstanding stability even without any encapsulation, whose initial performance is well maintained after aging 1000 h in humid air of 50% RH or continuous on–off light illumination for 20 h. This work will pave the way to produce new families of high‐performance, stable, and nontoxic perovskite SCTF for future optoelectronic applications.     

Controlling the Intermediate Phase to Improve the Crystallinity and Orientation of Cs3Sb2ClxI9-x Films for Efficient Solar Cells

Lead-free 2D antimony-based halide perovskites with excellent optoelectronic properties, low toxicity, and good intrinsic stability are promising for photovoltaic devices. However, the power conversion efficiency (PCE) of antimony-based perovskite solar cells (PSCs) is still lower than 3% due to the poor crystallinity and random orientation. Herein, it is found that the Cs₃Sb₂Cl_xI_9-x films prepared by adding methylamine chloride as an additive to the precursor solution can form a mixed intermediate phase with 0D dimer phase and 2D layered phase after low pressure treatment. During the annealing process, the 0D dimer phase will completely transition to 2D layered phase due to the partial replacement of I by Cl. Compared to adding SbCl₃ directly, this method considerably increases the crystallinity of Cs₃Sb₂I_xCl_9-x films. The obtained films have a preferential orientation along the (201) direction, which is beneficial for charge carrier transportation. Consequently, the champion device shows a PCE of 3.2%, which is one of the highest efficiencies achieved for inorganic Sb-based PSCs with the n-i-p architecture to date.