Tin Vacancies Research Articles

Minimizing voltage losses in Sn perovskite solar cells by Cs2SnI6 passivation

AbstractStability and oxidation are major bottlenecks in improving the performance of Sn‐based perovskite solar cells. In this study, we present the formation of an n‐type Cs2SnI6 double‐perovskite (Sn‐DP) layer on a (PEAI)0.15(FAI)0.85SnI2 perovskite (Sn‐P) layer using an orthogonal solution‐processable spray‐coating method. This novel approach achieves a minimized Voc loss of 0.38 V and a PCE of 12.9% under 1 sun conditions. The n‐type DP layer effectively passivates tin vacancies, suppresses Sn2+ oxidation, reduces defects, and enhances electron extraction. Furthermore, the Sn‐DP/Sn‐P‐based solar cells exhibit excellent light‐soaking stability for 1000 h in the air under continuous one sun illumination, which is attributed to the stable Sn4+ state of the DP layer. Our experimental and theoretical investigations reveal that the type‐II band alignment between Sn‐DP and Sn‐P enhances the stability of the solar cells. The proposed Sn‐DP/Sn‐P architecture offers a promising pathway for developing Sn‐based solar cells.image

Green Synthesis of Chitosan-coated Tin Dioxide Nanoparticles Using Moringa oleifera Flower Extract Against Breast Cancer via the Caspase-dependent Apoptotic Pathway

Background and Purpose In the present work, chitosan is furnished with tin dioxide (CsSnO2) nanoparticles (NPs) synthesized using the green route using Moringa oleifera ( M. oleifera) flower extract. Methods These preparation methods are low-cost, easily reproducible, nontoxic, and eco-friendly. X-ray diffraction (XRD), dynamic light scattering (DLS), field emission scanning electron microscope (FESEM), energy dispersive X-ray, Fourier-transform infrared spectroscopy (FT-IR), and photoluminescence (PL) analysis were used to learn more about the CsSnO2 NPs. The antibacterial property of CsSnO2 NPs was assessed by the disc diffusion method against various pathogens. The MTT assay was done to assess the cytotoxicity of CsSnO2 NPs in MCF-7 cells. The expressions of the apoptotic proteins were examined using assay kits. Results XRD results demonstrated that the formulated CsSnO2 NPs exhibit a tetragonal structure. From the FT-IR spectra, the Sn–O stretching peak was observed at 579 cm–1. A FESEM image shows that the CsSnO2 NPs were formed into a spherical structure. Surface defects, such as tin and oxygen vacancies, are visible in the PL spectra, and the average particle size of CsSnO2 NPs is 32 nm. Thus, surface defects are essential parameters for biocidal properties. The antimicrobial property of CsSnO2 NPs and amoxicillin was investigated against bacteria and human fungal pathogens. CsSnO2 NPs exhibit similar antimicrobial properties as compared to amoxicillin. Also, the dosage of CsSnO2 NPs elevated their antimicrobial activity. The anticancer property of the green-synthesized CsSnO2 NPs against MCF-7 cells was further analyzed to study their ability to cytotoxicity and apoptosis induction, like caspase-3, -8, and -9 activation. Conclusion The study’s outcome revealed that the green synthesized CsSnO2 NPs are an outstanding candidate for cancer therapy.

Multifunctional Acetaminophen Interlayer for High Efficiency and Durability Lead-Lean Perovskite Solar Cells.

Due to the easy oxidation of Sn2+, which leads to form tin vacancy defects and poor perovskite film quality, caused by the rapid crystallization rate in tin-based perovskite solar cells (PSCs), their efficiency lags far behind that of lead-based PSCs. To improve the photovoltaic (PV) performance and stability of FA0.9PEA0.1SnI3-based PSCs (T-PSCs), a small amount of Pb(SCN)2 is introduced into a perovskite precursor as an antioxidant, and acetaminophen (ACE) with various functional groups is used to modify a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/perovskite interface. The results show that the Pb(SCN)2 additive and ACE interfacial modification can not only optimize energy level alignment in T-PSCs but also inhibit Sn2+ oxidation to reduce the trap-state density, resulting in promoted carrier transport. The synergetic effect of the Pb(SCN)2 antioxidant and ACE interfacial modification significantly reduces nonradiative recombination and improves the PV performance and stability of T-PSCs. Consequently, the unsealed T-PSCs with the Pb(SCN)2 additive and ACE modification achieve a champion efficiency of 12.04% and maintain 99% of their initial PCE after being stored in N2 for more than 2100 h, while reference T-PSCs demonstrate a champion PCE of 6.20% and retain only 72% of its initial PCE. Moreover, the modified T-PSCs without encapsulation demonstrate much better stability in humid air.

Green-assisted synthesis of highly defective nanostructured Fe-doped SnO2: Magnetic and photocatalytic properties evaluation

Here we present a comprehensive characterization of the properties of undoped and Fe-doped SnO2 nanoparticles prepared with Syzygium cumini leaves extract. The phytochemicals present in the leaves extract act as cation chelating and capping of the nanoparticles. It is observed a relative high concentration of tin (up to 10 %) and oxygen (up to 5%) vacancies promoted by surface adsorbed OH− and by Fe-doping, respectively. The magnetic characterization reveals a ferromagnetic with a saturation monetization up to 20×10−3 emu/g for the higher defective and Fe-doped sample. This behavior associated mainly to tin vacancies for the undoped samples, and to the formation of bound magnetic polarons between the incorporated Fe and the oxygen vacancies for the doped samples. Oxygen vacancies and incorporated Fe improve the SnO2 photocatalytic efficiency in the visible range of the electromagnetic spectrum by decreasing the SnO2 effective bandgap from 3.6 eV for the undoped SnO2 sample to only 1.9 eV for the Fe-doped SnO2 sample, and by acting as electron-trapping centers increasing the system quantum efficiency. Due to the ferromagnetic behavior of the studied samples, it was also considered the effect of spin-dependent processes in the observed photocatalytic improvement. Our results highlight the key role of defect engineering strategies to optimize the physical and chemical properties of semiconductor oxides for application in the development of spintronic and quantum information devices, and in systems devoted to wastewater purification through advanced oxidation processes.

Tuning of power factor in bismuth selenide through Sn/Te co doping for low temperature thermoelectric applications

The physical parameters of solid-state produced tin and tellurium co-doped bismuth selenide polycrystalline crystals were described. Powder X-ray diffraction revealed the hexagonal structure in the samples’ phase domination. A field emission scanning electron microscope was used to analyze the surface microstructure. Thermoelectric properties such as Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed in the temperature range 10–350 K. The electrical resistivity of (Bi0.96Sn0.04)2Se2.7Te0.3 was found to be four times lower than that of pure Bi2Se3. Due to donor-like effects and antisite defects, the Seebeck coefficient demonstrates a p- to n-type semiconducting transition. When compared to pure Bi2Se3, power factor and thermoelectric figure of merit of (Bi0.96Sn0.04)2Se2.7Te0.3 is found to increase by 15 and 9 times respectively. Tellurium excess boosts tin vacancies, promoting the p to n-type transition in (Bi0.96Sn0.04)2Se2.7Te0.3, making it a good option for low temperature thermoelectric and sensor applications.

Phosphate-based ionic liquids for advanced interface modification in perovskite photovoltaics: Novel insights for ionic liquid molecule design

Interface modification stands out as a crucial method to enhance the performance of perovskite solar cells. This study explores the utilization of the ionic liquid 1-Methyl-3-propylimidazolium phosphate (MPIMPH), containing phosphate (PO43−) groups, as a modifier for SnO2/perovskite interfaces. Detailed investigations delve into the specific impact of IL MPIMPH on defects in tin dioxide, perovskite defects, perovskite crystallization, morphology, and overall device performance. Initially, Density Functional Theory (DFT) is employed to evaluate the defect passivation potential of different anions on tin vacancies within the SnO2 matrix, revealing the exceptional defect passivation ability of the PO43− group. Chemical interactions between ILs MPIMPH and SnO2, as well as perovskite, are confirmed, establishing a fundamental basis for interface defect passivation. ILs-based interface modification enhances interface contact, influencing the lead iodide conversion into perovskite and perovskite crystallization, ultimately leading to the formation of high-quality perovskite thin films. ILs also effectively suppress interfacial charge recombination and optimize the energy alignment of the SnO2/perovskite interface to enhance carrier extraction. Benefiting from the interface modification with ILs, the optimized device achieved an impressive device efficiency of 24.24 % with remarkable durability. This work provides an novel aspect for designing ionic liquids to enhance interface modification, contributing to upscaling and application of perovskite photovoltaics.

Alignment-free coupling to arrays of diamond microdisk cavities with fabrication tolerant spin-photon interfaces.

We propose a design for an efficient spin-photon interface to a color center in a diamond microdisk. The design consists of a silicon oxynitride triangular lattice overlaid on a diamond microdisk without any aligmnent between the layers. This enables vertical emission from the microdisk into low-numerical aperture modes, with quantum efficiencies as high as 46% for a tin vacancy (SnV) center. Our design is robust to manufacturing errors, potentially enabling large scale fabrication of quantum emitters coupled to optical collection modes. We also introduce a novel approach for optimizing the free space performance of our device using a dipole model, achieving comparable results to full-wave finite difference time domain simulations with 7 · 106 reduction in computational time.

An Emerging Stannous Fluoride Complex‐Enabled Highly Efficient Electron Collection and High Stability of Tin‐Based Perovskite Solar Cells

In advancing high‐performance tin‐based perovskite solar cells, rapid crystallization and oxidation susceptibility are key challenges. SnF2, often added to control crystallization and oxidation, may impact cell performance, particularly postannealing. This study uses in situ variable‐temperature X‐Ray diffraction to examine SnF2's physicochemical behavior and phase transitions in these cells. The analysis highlights how residual SnF2 affects carrier recombination through energy‐level structures. Postfilm formation, SnF2 chemically interacts with 2,2′:6′,2″‐Terpyridine (TPY), forming a stannous fluoride complex that enhances electron transport and energy alignment. Crucially, TPY passivates surface defects and reduces tin vacancies, boosting device stability. The experimental results indicate that the unencapsulated devices in air atmosphere exhibit a stabilized power output retention rate above 90% of the initial efficiency after 29.5 h. After ≈800 h of continuous illumination in ambient air, the conversion efficiency can still be maintained above 100%. Remarkably, t90 (time to retain 90% efficiency) of the target device in pure oxygen is over 24 h.

Nanoelectromechanical Control of Spin-Photon Interfaces in a Hybrid Quantum System on Chip.

Color centers (CCs) in nanostructured diamond are promising for optically linked quantum technologies. Scaling to useful applications motivates architectures meeting the following criteria: C1 individual optical addressing of spin qubits; C2 frequency tuning of spin-dependent optical transitions; C3 coherent spin control; C4 active photon routing; C5 scalable manufacturability; and C6 low on-chip power dissipation for cryogenic operations. Here, we introduce an architecture that simultaneously achieves C1-C6. We realize piezoelectric strain control of diamond waveguide-coupled tin vacancy centers with ultralow power dissipation necessary. The DC response of our device allows emitter transition tuning by over 20 GHz, combined with low-power AC control. We show acoustic spin resonance of integrated tin vacancy spins and estimate single-phonon coupling rates over 1 kHz in the resolved sideband regime. Combined with high-speed optical routing, our work opens a path to scalable single-qubit control with optically mediated entangling gates.

Low-temperature one-pot synthesis of tin(II) sulfide nanocrystalline thin films

Photosensitive thin films of tin (II) sulfide with p-type conductivity and a band gap of 1.03 ± 0.09 eV have been obtained within the framework of the principles of «green chemistry» using the one-pot approach. In order to expand the range of sulfidizers used in the technology of deposition of thin nanostructured SnS films by chemical deposition, the efficiency of using sodium thiosulfate solutions is shown. It has been found that thin SnS films with good adhesion to a dielectric substrate and a size of coherent scattering regions of about 30 nm can be obtained as a result of a chemical reaction of the hydrolytic decomposition of thiosulfate ions. The conditions for obtaining SnS are substantiated by the thermodynamic analysis of ionic equilibria. Quantum-chemical calculations show that the p-type conductivity of the synthesized SnS films is most likely due to tin vacancies.

Low-temperature anomalies of the dielectric permeability of Sn2P2S6 crystals

Low-temperature anomalies of dielectric permittivity of Sn2P2S6 crystals were investigated. It is shown that these phenomena have a relaxation character and the observed anomalies could be related to the small hole polarons dynamics with donor-acceptor compensation processes in lattice with tin and sulfur vacancies. To confirm it, we measured the dielectric properties of tin-enriched and sulfur-enriched crystals. It is shown that deviation from stoichiometry leads to a significant change in the low-temperature anomalies of dielectric losses.

‘Sawfish’ Photonic Crystal Cavity for Near‐Unity Emitter‐to‐Fiber Interfacing in Quantum Network Applications

AbstractPhoton loss is one of the key challenges to overcome in complex photonic quantum applications. Photon collection efficiencies directly impact the amount of resources required for measurement‐based quantum computation and communication networks. Promising resources include solid‐state quantum light sources. However, efficiently coupling light from a single quantum emitter to a guided mode remains demanding. In this work, photon losses are eliminated by maximizing coupling efficiencies in an emitter‐to‐fiber interface. A waveguide‐integrated ‘Sawfish’ photonic crystal cavity is developed and finite element (FEM) simulations are employed to demonstrate that such an emitter‐to‐fiber interface transfers, with 97.4 % efficiency, the zero‐phonon line (ZPL) emission of a negatively‐charged tin vacancy center in diamond (SnV−) adiabatically to a single‐mode fiber. A surrogate model trained by machine learning provides quantitative estimates of sensitivities to fabrication tolerances. The corrugation‐based Sawfish design proves robust under state‐of‐the‐art nanofabrication parameters, maintaining an emitter‐to‐fiber coupling efficiency of 88.6 %. Applying the Sawfish cavity to a recent one‐way quantum repeater protocol substantiates its potential in reducing resource requirements in quantum communication.

How Halide Alloying Influences the Optoelectronic Quality in Tin-Halide Perovskite Solar Absorbers.

Halide alloying in tin-based perovskites allows for photostable bandgap tuning between 1.3 and 2.2 eV. Here, we elucidate how the band edge energetics and associated defect activity impact the optoelectronic properties of this class of materials. We find that by increasing the bromide:iodide ratio, a simultaneous destabilization of acceptor defects (tin vacancies and iodine interstitials) and stabilization of donor defects (iodine vacancies and tin interstitials) occurs, with strong changes arising for Br contents exceeding 50%. This translates into a decreased doping which is, however, accompanied by a higher density of nonradiative recombination channels. Films with high Br content show a high degree of disorder and trap state densities, with the best optoelectronic quality being found for Br contents of around 33%. These observations match the open circuit voltage trend of tin-based mixed halide perovskite solar cells, supporting the relevance of optoelectronic properties and chemistry of defects to optimize wide-bandgap tin perovskite devices.

Incorporating Potassium Citrate to Improve the Performance of Tin‐Lead Perovskite Solar Cells

AbstractEasy‐to‐form tin vacancies at the buried interface of tin‐lead perovskites hinder the performance of low‐bandgap perovskite solar cells (PSCs). Here, a synergistic strategy by incorporating potassium citrate (PC) into the poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole‐transport layer to passivate the buried interface of Sn‐Pb PSCs is reported. PC neutralizes the acidity of PEDOT:PSS and stabilizes the perovskite front surface, enhancing device stability. Citrate moieties coordinate with Sn2+ on the buried perovskite surface, preventing Sn2+ oxidation and suppressing defect formation. Additionally, potassium cations incorporate into Sn‐Pb perovskites, enhancing crystallinity and passivating halide defects. The combined benefits enable efficient low‐bandgap Sn‐Pb PSCs with a power conversion efficiency of 22.7% and a high open‐circuit voltage of 0.894 V. Using this method, 26.1% efficiency for all‐perovskite tandem solar cells is demonstrated. These results emphasize the significance of buried interface passivation in developing efficient and stable Sn‐Pb PSCs and all‐perovskite tandem solar cells.

Tin Doping Induced High‐Performance Solution‐Processed Ga2O3 Photosensor toward Neuromorphic Visual System

AbstractGa2O3 is an emerging wide‐bandgap semiconductor with high deep ultraviolet absorption, tunable persistent photoconductivity, and excellent stability toward electric fields, making it a promising component for neuromorphic visual systems (NVSs). However, Ga2O3‐based photosensors with high responsivity and long response decay times are required for efficient NVSs. A solution‐processed doping strategy for fabrication of Ga2O3 is proposed with tin foil as a dopant source. Tin‐doped Ga2O3 (Ga2O3:Sn) photosensors are obtained with ultrahigh responsivity and extremely long response decay times. These behaviors are attributed to substitutional tin and oxygen vacancies that modulate defect‐related hole trapping. High‐performance Ga2O3:Sn photosensors can mimic photonic synaptic behaviors and image pre‐processing functions. NVSs based on a Ga2O3:Sn photonic synapse array perform pattern recognition with an accuracy of 97.3% under an unprecedented low‐light pulse stimuli of 0.5 µW cm−2. This work provides a low‐cost solution‐processed approach to ultrasensitive Ga2O3:Sn NVSs and will facilitate developments in artificial intelligence technology.

Improved thermoelectric performance by microwave wet chemical synthesis of low thermal conductivity SnTe

SnTe is a promising replacement for PbTe due to its non-toxicity and high thermoelectric conversion efficiency. However, it suffers from poor performance caused by the presence of tin vacancies and a wide energy gap between the light and heavy valence bands, as well as high thermal conductivity that inhibits its thermoelectric properties. In this work, complexes of in situ grown SnTe with Bi doping were synthesized by microwave wet chemical synthesis. The complex morphology of the micro-nanoparticles and the formation of holes after spark plasma sintering suppress phonon scattering and greatly reduce the lattice thermal conductivity of the system. The band structure and phonon dispersion of Bi doped SnTe were calculated by first principles, and the reasons for the improvement of electric transport properties and the decrease of thermal conductivity of SnTe were investigated, combined with mechanical properties and sound speed reduction. The effects of various mechanisms such as polycrystalline interfaces, point defects, complex morphologies, and phonon dispersion flat bands on phonon scattering are discussed in detail and the obtaining mechanism of low lattice thermal conductivity is understood.

Exciton Localization for Highly Luminescent Two‐Dimensional Tin‐Based Hybrid Perovskites through Tin Vacancy Tuning

AbstractExciton localization is an approach for preparing highly luminescent semiconductors. However, realizing strongly localized excitonic recombination in low‐dimensional materials such as two‐dimensional (2D) perovskites remains challenging. Herein, we first propose a simple and efficient Sn2+ vacancy (VSn) tuning strategy to enhance excitonic localization in 2D (OA)2SnI4 (OA=octylammonium) perovskite nanosheets (PNSs), increasing their photoluminescence quantum yield (PLQY) to ≈64 %, which is among the highest values reported for tin iodide perovskites. Combining experimental with first‐principles calculation results, we confirm that the significantly increased PLQY of (OA)2SnI4 PNSs is primarily due to self‐trapped excitons with highly localized energy states induced by VSn. Moreover, this universal strategy can be applied for improving other 2D Sn‐based perovskites, thereby paving a new way to fabricate diverse 2D lead‐free perovskites with desirable PL properties.

Exciton Localization for Highly Luminescent Two-Dimensional Tin-Based Hybrid Perovskites through Tin Vacancy Tuning.

Exciton localization is an approach for preparing highly luminescent semiconductors. However, realizing strongly localized excitonic recombination in low-dimensional materials such as two-dimensional (2D) perovskites remains challenging. Herein, we first propose a simple and efficient Sn2+ vacancy (VSn ) tuning strategy to enhance excitonic localization in 2D (OA)2 SnI4 (OA=octylammonium) perovskite nanosheets (PNSs), increasing their photoluminescence quantum yield (PLQY) to ≈64 %, which is among the highest values reported for tin iodide perovskites. Combining experimental with first-principles calculation results, we confirm that the significantly increased PLQY of (OA)2 SnI4 PNSs is primarily due to self-trapped excitons with highly localized energy states induced by VSn . Moreover, this universal strategy can be applied for improving other 2D Sn-based perovskites, thereby paving a new way to fabricate diverse 2D lead-free perovskites with desirable PL properties.

Atomic Model for Alkali Metal-Doped Tin–Lead Mixed Perovskites: Insight from Quantum Dynamics

Defects such as metal vacancies act as nonradiative recombination centers to deteriorate the photoelectric properties of metal halide perovskites. Nonadiabatic molecular dynamics has demonstrated that alkali metal dopants markedly improve the performance of mixed tin-lead perovskites. Alkali dopants increase the formation energy of tin vacancies to 1 eV, so that the defect concentration is decreased. When tin vacancies exist, alkali metals are easily doped into perovskites. Tin vacancies produce iodine trimers that create midgap states and cause rapid electron-hole recombination. Alkali metal additives eliminate the trap state, weaken nonadiabatic coupling, and decelerate charge recombination with a coefficient of ≤5.5 compared with the performance of the defective tin-lead mixed perovskite. Our research has constructed a theoretical model at the atomic level for alkali metal passivation that enhances defect tolerance of tin-lead mixed perovskites, generating valuable inspiration for optimizing high-performance perovskites.

Interfacial Engineering of Au@Nb2CTx-MXene Modulates the Growth Strain, Suppresses the Auger Recombination, and Enables an Open-Circuit Voltage of over 1.2 V in Perovskite Solar Cells

Defects at the interface of charge transport layers can cause severe charge accumulation and poor charge transferability, which greatly affect the efficiency and stability of stannic oxide (SnO2)-based perovskite solar cells (PSCs). Herein, a new type of MXene (Nb2CTx-MXene) is applied to the interface of SnO2 layers to passivate the interfacial defects and promote charge transport. Nb2CTx-MXene in PSCs realizes the role of boosting the conductivity, reducing the tin vacancies in the interstitial void of the SnO2 layer, decreasing the defect density, and aligning the bandgap. Afterward, Nb2CTx-MXene is decorated with gold nanospheres, which has the ability to modulate the tensile strain of perovskites and suppress the Auger recombination. Eventually, the Au@Nb2CTx-MXene-modified device yields an excellent power conversion efficiency (PCE) of 23.78% with a relatively high open-circuit voltage of 1.215 V (Eg ∼ 1.60 eV). The unencapsulated devices maintain 90% of their initial PCE values after storage in the air with a relative humidity of 40% for 1000 h and remain above 80% of their initial efficiency after operation at the maximum power point for 500 h under 1 sun illumination. Our work provides an avenue to fabricate high-efficiency and stable PSCs with MXene adapting to commercial development.