Organic Cation‐Dependent Degradation Mechanism of Organotin Halide Perovskites

The applications of organotin halide perovskites are limited because of their chemical instability under ambient conditions. Upon air exposure, Sn²⁺ can be rapidly oxidized to Sn⁴⁺, causing a large variation in the electronic properties. Here, the role of organic cations in degradation is investigated by comparing methylammonium tin iodide (MASnI₃) and formamidinium tin iodide (FASnI₃). Through chemical analyses and theoretical calculations, it is found that the organic cation strongly influences the oxidation of Sn²⁺ and the binding of H₂O molecules to the perovskite lattice. On the one hand, Sn²⁺ can be easily oxidized to Sn⁴⁺ in MASnI₃, and replacing MA with FA reduces the extent of Sn oxidation; on the other hand, FA forms a stronger hydrogen bond with H₂O than does MA, leading to partial expansion of the perovskite network. The two processes compete in determining the material's conductivity. It is noted that the oxidation is a difficult process to prevent, while the water effect can be largely suppressed by reducing the moisture level. As a result, FASnI₃‐based conductors and photovoltaic cells exhibit much better reproducibility as compared to MASnI₃‐based devices. This study sheds light on the development of stable Pb‐free perovskite optoelectronic devices through new material design.     

Mechanism of Crystal Formation in Ruddlesden–Popper Sn‐Based Perovskites

Knowledge of the mechanism of formation, orientation, and location of phases inside thin perovskite films is essential to optimize their optoelectronic properties. Among the most promising, low toxicity, lead‐free perovskites, the tin‐based ones are receiving much attention. Here, an extensive in situ and ex situ structural study is performed on the mechanism of crystallization from solution of 3D formamidinium tin iodide (FASnI₃), 2D phenylethylammonium tin iodide (PEA₂SnI₄), and hybrid PEA₂FA_n?1Sn_nI_3n+1 Ruddlesden–Popper perovskites. Addition of small amounts of low‐dimensional component promotes oriented 3D‐like crystallite growth in the top part of the film, together with an aligned quasi‐2D bottom‐rich phase. The sporadic bulk nucleation occurring in the pure 3D system is negligible in the pure 2D and in the hybrid systems with sufficiently high PEA content, where only surface crystallization occurs. Moreover, tin‐based perovskites form through a direct conversion of a disordered precursor phase without forming ordered solvated intermediates and thus without the need of thermal annealing steps. The findings are used to explain the device performances over a wide range of composition and shed light onto the mechanism of the formation of one of the most promising Sn‐based perovskites, providing opportunities to further improve the performances of these interesting Pb‐free materials.     

Cooling,Scattering, and Recombination—The Role of the Material Quality for the Physics of Tin Halide Perovskites

Tin‐based perovskites have long remained a side topic in current perovskite optoelectronic research. With the recent efficiency improvement in thin film solar cells and the observation of a long hot carrier cooling time in formamidinium tin iodide (FASnI₃), a thorough understanding of the material's photophysics becomes a pressing matter. Since pronounced background doping can easily obscure the actual material properties, it is of paramount importance to understand how different processing conditions affect the observed behavior. Using photoluminescence spectroscopy, thin films of FASnI₃ fabricated through different protocols are therefore investigated. It is shown that hot carrier relaxation occurs much faster in highly p‐doped films due to carrier–carrier scattering. From high quality thin films, the longitudinal optical phonon energy and the electron–phonon coupling constant are extracted, which are fundamental to understanding carrier cooling. Importantly, high quality films allow for the observation of a previously unreported state of microsecond lifetime at lower energy in FASnI₃, that has important consequences for the discussion of long lived emission in the field of metal halide perovskites.     

Stabilization of Perovskite Lattice and Suppression of Sn2+/Sn4+ Oxidation via Formamidine Acetate for High Efficiency Tin Perovskite Solar Cells

Tin halide lead-free perovskite solar cells (TPSCs) have received tremendous research interest recently due to their nearly ideal bandgap, broad light absorption, non-toxicity, and environmental friendliness. However, the uncontrollable crystallization process and the facile oxidation of Sn²⁺ limit the further increase of power conversion efficiency (PCE). To solve these problems, a series of acetates are introduced into the perovskite precursor solution to regulate the crystallization process. It is revealed that formamidine acetate (FAAc) has strong CO Sn coordination with Sn²⁺ compared with acetic acid (HAc) and methylammonium acetate (MAAc), which can stabilize the lattice structure, minimize defect states and suppress the oxidation of Sn²⁺. Meanwhile, benefiting from this coordination ability, it not only leads to large-size colloidal clusters in precursor but also slows down the crystallization process and improves the crystallinity of tin halide perovskite films. The device with FAAc achieved an increased PCE from initially 9.84% to 12.43%, and it could maintain 94% of its initial value for 2000 h in N₂ atmosphere. This work provides a feasible strategy for depositing high-quality tin perovskite films with low defect density and lattice distortion, which will be crucial for related photovoltaics and other optoelectronic devices.     

Orientation Regulation of Tin‐Based Reduced‐Dimensional Perovskites for Highly Efficient and Stable Photovoltaics

Tin‐based perovskites have exhibited high potential for efficient photovoltaics application due to their outstanding optoelectrical properties. However, the extremely undesired instabilities significantly hinders their development and further commercialization process. A novel tin‐based reduced‐dimensional (quasi‐2D) perovskites is reported here by using 5‐ammoniumvaleric acid (5‐AVA⁺) as the organic spacer. It is demonstrated that by introducing appropriate amount of ammonium chloride (NH₄Cl) as additive, highly vertically oriented tin‐based quasi‐2D perovskite films are obtained, which is proved through the grazing incidence wide‐angle X‐ray scattering characterization. In particular, this approach is confirmed to be a universal method to deliver highly vertically oriented tin‐based quasi‐2D perovskites with various spacers. The highly ordered vertically oriented perovskite films significantly improve the charge collection efficiency between two electrodes. With the optimized NH₄Cl concentration, the solar cells employing quasi‐2D perovskite, AVA₂FA_n?1Sn_nI_3n+1 (<n> = 5), as light absorbers deliver a power conversion efficiency up to 8.71%. The work paves the way for further employing highly vertically oriented tin‐based quasi‐2D perovskite films for highly efficient and stable photovoltaics.     

A Dual‐Retarded Reaction Processed Mixed‐Cation Perovskite Layer for High‐Efficiency Solar Cells

Mixed‐cation perovskite solar cells (PSCs) have become of enormous interest because of their excellent efficiency, which is now crossing 23.7%. Their broader absorption, relatively high stability with low fabrication cost compared to conventional single phase ABX₃ perovskites (where A: organic cation; B: divalent metal ion; and X: halide anion) are key properties of mixed‐halide mixed‐cation perovskites. However, the controlling reaction rate and formation of extremely dense, textured, smooth, and large grains of perovskite layer is a crucial task in order to achieve highly efficient PSCs. Herein, a new simple dual‐retarded reaction processing (DRP) method is developed to synthesize a high‐quality mixed‐cation (FAPbI₃)_0.85(MAPbBr₃)_0.15 (where MAPbBr₃ stands for methylammonium lead bromide and FAPbI₃ stands for formamidinium lead iodide) perovskite thin film via intermediate phase and incorporation of nitrogen‐doped reduced graphene oxide (N‐rGO). The reaction rate is retarded via two steps: first the formation of intermediate phase and second the interaction of the nitrogen groups on N‐rGO with hydrogen atoms from formamidinium cations. This DRP process allows for the fabrication of PSCs with maximum conversion efficiency higher than 20.3%.     

Making Room for Growing Oriented FASnI3 with Large Grains via Cold Precursor Solution

Tin halide perovskites are promising candidates for preparing efficient lead-free perovskite solar cells due to their ideal band gap and high charge-carrier mobility. However, the notorious rapid crystallization process results in the inferior power conversion efficiency (PCE) of tin perovskite solar cells (TPSCs). Here, a facile method is employed to manage this crystallization process by using cold precursor solution that raises the critical Gibbs free energy to slow down the nucleation rate, sparing both space and time for crystal growth. In this way, highly oriented FASnI₃ films with micrometer-scale grains are fabricated and an increase of 70 mV in the open-circuit voltage is obtained for TPSCs. This method is compatible with other existed strategies such as additive engineering or the post-treatment method. The best-performing device that combines 0 °C precursor solution and post-treatment method demonstrates a PCE of 12.11%.     

An Interdiffusion Method for Highly Performing Cesium/Formamidinium Double Cation Perovskites

The fabrication of high‐quality cesium (Cs)/formamidinium (FA) double‐cation perovskite films through a two‐step interdiffusion method is reported. Cs_x FA_1‐x PbI_{3‐y(1‐x )}Br_{y(1‐x )} films with different compositions are achieved by controlling the amount of CsI and formamidinium bromide (FABr) in the respective precursor solutions. The effects of incorporating Cs⁺ and Br^? on the properties of the resulting perovskite films and on the performance of the corresponding perovskite solar cells are systematically studied. Small area perovskite solar cells with a power conversion efficiency (PCE) of 19.3% and a perovskite module (4 cm²) with an aperture PCE of 16.4%, using the Cs/FA double cation perovskite made with 10 mol% CsI and 15 mol% FABr (Cs_0.1FA_0.9PbI_2.865Br_0.135) are achieved. The Cs/FA double cation perovskites show negligible degradation after annealing at 85 °C for 336 h, outperforming the perovskite materials containing methylammonium (MA).     

Octadecylamine‐Functionalized Single‐Walled Carbon Nanotubes for Facilitating the Formation of a Monolithic Perovskite Layer and Stable Solar Cells

Organic–inorganic lead halide perovskites have shown great future for application in solar cells owing to their exceptional optical and electronic properties. To achieve high‐performance perovskite solar cells, a perovskite light absorbing layer with large grains is desirable in order to minimize grain boundaries and recombination during the operation of the device. Herein, a simple yet efficient approach is developed to synthesize perovskite films consisting of monolithic‐like grains with micrometer size through in situ deposition of octadecylamine functionalized single‐walled carbon nanotubes (ODA‐SWCNTs) onto the surface of the perovskite layer. The ODA‐SWCNTs form a capping layer that controls the evaporation rate of organic solvents in the perovskite film during the postthermal treatment. This favorable morphology in turn dramatically enhances the short‐circuit current density of the perovskite solar cells and almost completely eliminates the hysteresis. A maximum power conversion efficiency of 16.1% is achieved with an ODA‐SWCNT incorporated planar solar cell using (FA_0.83MA_0.17)_0.95Cs_0.05Pb(I_0.83Br_0.17)₃ as light absorber. Furthermore, the perovskite solar cells with ODA‐SWCNT demonstrate extraordinary stability with performance retention of 80% after 45 d stability testing under high humidity (60–90%) environment. This work opens up a new avenue for morphology manipulation of perovskite films and enhances the device stability using carbon material.     

Triamine‐Based Aromatic Cation as a Novel Stabilizer for Efficient Perovskite Solar Cells

Operational stability of perovskite solar cells has been a challenge from the beginning of perovskite research. In general, humidity and heat are the most well‐known degradation sources for perovskites, requiring ideal design of perovskite chemistry to withstand them. Although triple‐cation perovskite (Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃) has been already introduced as the stable perovskite material, the high reactivity of methylammonium and formamidinium in the cation sites demands further modification. Herein, 1,2,4‐triazole is suggested as an effective cation solute to improve the performance and stability of perovskite solar cells. 1,2,4‐Triazole is an aromatic cation with low dipole moment that is stable under humidity and heat. It also possesses three nitrogen atoms, forming additional hydrogen bonds in the lattice, stabilizing the material. In this study, the solar cell utilizing 1,2,4‐triazole alloying achieves a power conversion efficiency of 20.9% with superior stability under extreme condition (85 °C/85% of relative humidity (RH), encapsulated) for 700 h. The 1,2,4‐triazole‐alloyed perovskite exhibits reduced trap density and film roughness and enhanced carrier lifetime with electrical conductivity, suggesting an ideal perovskite structure for efficient and stable optoelectronic applications.     

Overcoming Zinc Oxide Interface Instability with a Methylammonium‐Free Perovskite for High‐Performance Solar Cells

Perovskite solar cells have achieved the highest power conversion efficiencies on metal oxide n‐type layers, including SnO₂ and TiO₂. Despite ZnO having superior optoelectronic properties to these metal oxides, such as improved transmittance, higher conductivity, and closer conduction band alignment to methylammonium (MA)PbI₃, ZnO is largely overlooked due to a chemical instability when in contact with metal halide perovskites, which leads to rapid decomposition of the perovskite. While surface passivation techniques have somewhat mitigated this instability, investigations as to whether all metal halide perovskites exhibit this instability with ZnO are yet to be undertaken. Experimental methods to elucidate the degradation mechanisms at ZnO–MAPbI₃ interfaces are developed. By substituting MA with formamidinium (FA) and cesium (Cs), the stability of the perovskite–ZnO interface is greatly enhanced and it is found that stability compares favorably with SnO₂‐based devices after high‐intensity UV irradiation and 85 °C thermal stressing. For devices comprising FA‐ and Cs‐based metal halide perovskite absorber layers on ZnO, a 21.1% scanned power conversion efficiency and 18% steady‐state power output are achieved. This work demonstrates that ZnO appears to be as feasible an n‐type charge extraction layer as SnO₂, with many foreseeable advantages, provided that MA cations are avoided.     

Highly Sensitive Low‐Bandgap Perovskite Photodetectors with Response from Ultraviolet to the Near‐Infrared Region

It is a great challenge to obtain broadband response perovskite photodetectors (PPDs) due to the relatively large bandgaps of the most used methylammonium lead halide perovskites. The response range of the reported PPDs is limited in the ultraviolet–visible range. Here, highly sensitive PPDs are successfully fabricated with low bandgap (≈1.25 eV) (FASnI₃)_0.6(MAPbI₃)_0.4 perovskite as active layers, exhibiting a broadband response from 300 to 1000 nm. The performance of the PPDs can be optimized by adjusting the thicknesses of the perovskite and C₆₀ layers. The optimized PPDs with 1000 nm thick perovskite layer and 70 nm thick C₆₀ layer exhibit an almost flat external quantum efficiency (EQE) spectrum from 350 to 900 nm with EQE larger than 65% under ?0.2 V bias. Meanwhile, the optimized PPDs also exhibit suppressed dark current of 3.9 nA, high responsivity (R ) of over 0.4 A W^?1, high specific detectivity (D* ) of over 10¹² Jones in the near‐infrared region under ?0.2 V. Such highly sensitive broadband response PPDs, which can work well as self‐powered conditions, offer great potential applications in multicolor light detection.     

Boosting Photovoltaic Performance for Lead Halide Perovskites Solar Cells with BF4− Anion Substitutions

Composition engineering is a particularly simple and effective approach especially using mixed cations and halide anions to optimize the morphology, crystallinity, and light absorption of perovskite films. However, there are very few reports on the use of anion substitutions to develop uniform and highly crystalline perovskite films with large grain size and reduced defects. Here, the first report of employing tetrafluoroborate (BF₄^?) anion substitutions to improve the properties of (FA = formamidinium, MA = methylammonium (FAPbI₃)_0.83(MAPbBr₃)_0.17) perovskite films is demonstrated. The BF₄^? can be successfully incorporated into a mixed‐ion perovskite crystal frame, leading to lattice relaxation and a longer photoluminescence lifetime, higher recombination resistance, and 1–2 orders magnitude lower trap density in prepared perovskite films and derived solar cells. These advantages benefit the performance of perovskite solar cells (PVSCs), resulting in an improved power conversion efficiency (PCE) of 20.16% from 17.55% due to enhanced open‐circuit voltage (V_OC) and fill factor. This is the highest PCE for BF₄^? anion substituted lead halide PVSCs reported to date. This work provides insight for further exploration of anion substitutions in perovskites to enhance the performance of PVSCs and other optoelectronic devices.     

Highly Efficient Sn/Pb Binary Perovskite Solar Cell via Precursor Engineering: A Two‐Step Fabrication Process

Regulation of the crystallization of perovskite films and avoiding the oxidation of Sn²⁺ during the deposition process are very important for achieving Sn/Pb binary perovskite solar cells (PVSCs) with high power conversion efficiency (PCE) and producibility. In this work, a high‐quality HC(NH₂)₂Pb_0.7Sn_0.3I₃ (FAPb_0.7Sn_0.3I₃) film deposited from the two‐step solution process by introducing methylammonium thiocyanate (MASCN) as a bifunctional additive into the precursor solution containing PbI₂ and SnI₂ is reported. MASCN can not only tune the morphology of the perovskite film but also stabilize the precursor solution via retarding the oxidation of Sn²⁺ through a strong coordination between SCN^? and Sn²⁺. The Sn/Pb binary inverted PVSCs based on FAPb_0.7Sn_0.3I₃ present a high fill factor of 0.79 and the best PCE of 16.26% in the case of 0.25 MASCN addition. The device fabrication producibility is also greatly improved due to the stabilized precursor solution with the aid of MASCN. The PCE of the device is almost independent of the storage time of the precursor solution within 124 d in the N₂‐filled glove box. These results indicate that the precursor engineering with multifunctionality additive is an effective approach toward highly efficient and producible PVSCs for future commercialization.     

Precursor Solution Annealing Forms Cubic‐Phase Perovskite and Improves Humidity Resistance of Solar Cells

Solar cells with light‐absorbing layers comprising organometal halide perovskites have recently exceeded 22% efficiency. Despite high power‐conversion efficiencies, the stability of these devices, particularly when exposed to humidity and oxygen, remains poor. In the current study, a pathway to increase the stability of methylammonium lead iodide (CH₃NH₃PbI₃) based solar cells towards humidity is demonstrated, while maintaining the simplicity and solution‐processability of the active layers. Thermal annealing of the precursor solution prior to deposition induces the formation of cubic‐phase perovskite films in the solid state at room temperature. The experiments demonstrate that this improved ambient stability is correlated with the presence of the cubic phase at device operating temperatures, with the cubic phase resisting the formation of perovskite monohydrate—a pathway of degradation in conventionally processed perovskite thin films—on exposure to humidity.     

Dual Passivation of Perovskite Defects for Light‐Emitting Diodes with External Quantum Efficiency Exceeding 20%

Solution‐processed metal halide perovskites (MHPs) have attracted much attention for applications in light‐emitting diodes (LEDs) due to their wide color gamut, high color purity, tunable emission wavelength, balanced electron/hole transportation, etc. Although MHPs are very tolerant to defects, the defects in solution‐processed perovskite LEDs (PeLEDs) still cause severe nonradiative recombination and device instability. Here, molecular design of additives for dual passivation of both lead and halide defects in perovskites is reported. A bi‐functional additive, 4‐fluorophenylmethylammonium‐trifluoroacetate (FPMATFA), is synthesized by using a simple solution process. The TFA anions and FPMA cations can bond with undercoordinated lead and halide ions, respectively, resulting in dual passivation of both lead and halide defects. In addition, the bulky FPMA group can constrain the grain growth of 3D perovskite, enhancing electron–hole capture rates and radiative recombination rates. As a result, high‐performance PeLEDs with a peak external quantum efficiency reaching 20.9% and emission wavelength at 694 nm are achieved using formamidinium‐cesium lead iodide‐bromide (FA_0.33Cs_0.67Pb(I_0.7Br_0.3)₃). Furthermore, the operational lifetime of PeLEDs is also greatly improved due to the low trap density in the perovskite film.     

Highly Stable n–i–p Structured Formamidinium Tin Triiodide Solar Cells through the Stabilization of Surface Sn2+ Cations

Improving the performance, reproducibility, and stability of Sn-based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li-TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn-based PSC, Sn²⁺ is easily oxidized to Sn⁴⁺ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI₃)-based PSCs fabricated using DPI-TPFB [4-Isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li-TFSI are reported as a dopant in Spiro-OMeTAD. The DPI-TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI₃-based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI-TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn²⁺ through coordination with Sn²⁺ on the surface of FASnI₃.     

Highly Photoluminescent and Environmentally Stable Perovskite Nanocrystals Templated in Thin Self‐Assembled Block Copolymer Films

Ordered nanostructured crystals of thin organic–inorganic metal halide perovskites (OIHPs) are of great interest to researchers because of the dimensional‐dependence of their photoelectronic properties for developing OIHPs with novel properties. Top‐down routes such as nanoimprinting and electron beam lithography are extensively used for nanopatterning OIHPs, while bottom‐up approaches are seldom used. Herein, developed is a simple and robust route, involving the controlled crystallization of the OIHPs templated with a self‐assembled block copolymer (BCP), for fabricating nanopatterned OIHP films with various shapes and nanodomain sizes. When the precursor solution consisting of methylammonium lead halide (MAPbX₃, X = Br^?, I^?) perovskite and poly(styrene)‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) is spin‐coated on the substrate, a nanostructured BCP is developed by microphase separation. Spontaneous crystallization of the precursor ions preferentially coordinated with the P2VP domains yields ordered nanocrystals with various nanostructures (cylinders, lamellae, and cylindrical mesh) with controlled domain size (≈40–72 nm). The nanopatterned OIHPs show significantly enhanced photoluminescence (PL) with high resistance to both humidity and heat due to geometrically confining OIHPs in and passivation with the P2VP chains. The self‐assembled OIHP films with high PL performance provide a facile control of color coordinates by color conversion layers in blue‐emitting devices for cool‐white emission.     

High‐Performance Inverted Planar Heterojunction Perovskite Solar Cells Based on Lead Acetate Precursor with Efficiency Exceeding 18%

Organic–inorganic lead halide perovskites are emerging materials for the next‐generation photovoltaics. Lead halides are the most commonly used lead precursors for perovskite active layers. Recently, lead acetate (Pb(Ac)₂) has shown its superiority as the potential replacement for traditional lead halides. Here, we demonstrate a strategy to improve the efficiency for the perovskite solar cell based on lead acetate precursor. We utilized methylammonium bromide as an additive in the Pb(Ac)₂ and methylammonium iodide precursor solution, resulting in uniform, compact and pinhole‐free perovskite films. We observed enhanced charge carrier extraction between the perovskite layer and charge collection layers and delivered a champion power conversion efficiency of 18.3% with a stabilized output efficiency of 17.6% at the maximum power point. The optimized devices also exhibited negligible current density–voltage (J–V) hysteresis under the scanning conditions.     

Enhancing Performance and Stability of Tin Halide Perovskite Light Emitting Diodes via Coordination Engineering of Lewis Acid–Base Adducts

For resolving toxicity issues of Pb-based perovskites, Sn-based perovskites have been widely studied as a promising alternative due to similar valence electron configuration between Sn²⁺ and Pb²⁺. However, desired Sn²⁺ in the precursor solution and film is easily oxidized to Sn⁴⁺, causing detrimental Sn vacancies and impurities in the films. Unfortunately, dimethyl sulfoxide, a ubiquitously used Lewis base for the fabrication of high-quality perovskite thin films via the adduct approach, further accelerates the oxidation of Sn²⁺ in the precursor solution. Herein, N,N′-dimethylpropyleneurea (DMPU) is proposed as an alternative Lewis base for the fabrication of high-quality Sn-based perovskite thin films. The strongly coordinating Lewis base DMPU is shown to suppress the oxidation of Sn²⁺ in the precursor solution while promoting growth of uniform and highly crystalline thin films. The PEA₂SnI₄ perovskite light emitting diode (PeLED) based on DMPU demonstrates dramatically improves luminance (L): a more than sixfold enhanced external quantum efficiency (EQE) and better operational stability than those of the device fabricated without DMPU. The optimum PeLED based on DMPU achieves a maximum L and EQE of 68.84 cd m⁻² and 0.361%, respectively. This study provides an important methodological base for studying Sn perovskites for development of high-performance and eco-friendly PeLEDs.