Organic-inorganic Halide Perovskite Research Articles

Stabilizing Metal Halide Perovskite Films via Chemical Vapor Deposition and Cryogenic Electron Beam Patterning.

Halide perovskites are hailed as semiconductors of the 21st century. Chemical vapor deposition (CVD), a solvent-free method, allows versatility in the growth of thin films of 3- and 2D organic-inorganic halide perovskites. Using CVD grown methylammonium lead iodide (MAPbI3) films as a prototype, the impact of electron beam dosage under cryogenic conditions is evaluated. With 5 kV accelerating voltage, the dosage is varied between 50 and 50000 µC cm-2. An optimum dosage of 35 000 µC cm-2 results in a significant blue shift and enhancement of the photoluminescence peak. Concomitantly, a strong increase in the photocurrent is observed. A similar electron beam treatment on chlorine incorporated MAPbI3, where chlorine is known to passivate defects, shows a blue shift in the photoluminescence without improving the photocurrent properties. Low electron beam dosage under cryogenic conditions is found to damage CVD grown 2D phenylethlyammoinum lead iodide films. Monte Carlo simulations reveal differences in electron beam interaction with 3- and 2D halide perovskite films.

Steady-State Inverse-Temperature Crystallization Enabling Low Defect Perovskite Single Crystal and Efficient X-Ray Detectors.

Organic-inorganic halide perovskite single crystals (SCs) have shown great potential in radiation detection applications due to their large radiation stopping power and excellent carrier transport properties. The spatial-confined inverse-temperature crystallization (ITC) method has been widely adopted to obtain large-sized SCs. However, they usually face the problems of uneven stress distribution and high defect density due to the limited crystal growth space and varied growth rate with the increase in temperature, making it difficult to fabricate highly sensitive and stable radiation detectors. In this study, the steady-state inverse-temperature crystallization method (SS-ITC) is developed to regulate the growth process of SCs by controlling the growth speed precisely to achieve a constant rate of growth as the temperature increases. Compared with the conventional ITC-grown samples, the lattice spacing of SCs prepared by the SS-ITC method is reduced by 1.2% due to tensile stress relaxation, resulting in a lower defect density of 7.93×109cm-3 and a remarkable uniformity over a large area. As a result, the co-planar X-ray detectors based on these high-quality SCs exhibit a high sensitivity of 1.67×105 µC Gyair -1cm-2, representing the best performing MAPbBr3-based X-ray detectors reported to date.

Comprehensive device simulation of perovskite solar cell with CuFeO2 as hole transport layer

Abstract Solid-state organic-inorganic halide perovskite solar cells have attracted increasing interest due to their potential as high-efficiency, low-cost photovoltaic devices. In this study, we comprehensively simulate CH₃NH₃PbI₃ perovskite-based solar cells with CuFeO₂ as the hole transport material (HTM) layer, and compare them to cells using Spiro-OMETAD and Cu₂O as HTM layers, utilizing SCAPS-1D software. The effects of absorber thickness, back contact work function, CuFeO₂ thickness, acceptor concentration, and defect density at the CH₃NH₃PbI₃/CuFeO₂ interface are analyzed. The results indicate that delafossite CuFeO₂ is a promising HTM that could significantly enhance the performance of perovskite-based solar cells. TiO₂/CH₃NH₃PbI₃/CuFeO₂ solar cells demonstrate comparable photovoltaic performance to those using traditional Spiro-OMETAD when the back contact electrode work function exceeds 4.9 eV, and superior performance compared to those with Cu₂O and Spiro-OMETAD at work functions below 4.8 eV. A high acceptor concentration exceeding 10¹⁶ cm⁻³ in CuFeO₂ is recommended to achieve optimal photovoltaic performance. These simulation results highlight the significant potential of employing CuFeO₂ as an HTM layer in CH₃NH₃PbI₃ perovskite-based solar cells as an alternative to the organic Spiro-OMETAD.

Design and performance exploration of Pb-free low-cost all-inorganic perovskite-inspired CuAgBi2I8 solar cells: theoretical approach

Abstract Organic–inorganic halide perovskites have demonstrated great potential for photovoltaic applications owing to their unprecedented optoelectronic properties and low manufacturing costs. However, the commercialization of this technology is hindered by its thermal instability and inherent toxicity. In this study, SCAPS-1D simulation software was used to study the performance of solar cell based on CuAgBi2I8, which is a novel inorganic non-toxic lead-free perovskite-inspired material. Different electron transport layers (TiO2, In2S3, ZnO, Zn0.75Mg0.25O,SnO2 and SrTiO3) and hole transport layers (CuI, PEDOT:PSS, CuSCN and Cu2O) were studied, our research indicated that SnO2 and NiO formed the optimal combination. Further analysis revealed that the optimal absorption layer thickness was 900 nm, the absorption layer doping concentration should be less than 1 × 1013 cm−3 and the defect density should be less than 1 × 1014 cm−3. The optimal thickness of SnO2 and NiO was 30 nm, the optimal doping concentration of SnO2 and NiO was 1 × 1020 cm−3, the defect density of absorber layer/SnO2 and absorber layer/NiO interfaces should be less than 1 × 1012 cm−3, C was the optimal back electrode material. Consequently, the optimal device configuration was identified as FTO/SnO2/CuAgBi2I8/NiO/C, the efficiency was improved from original 2.76% to 19.10% after above optimization. These results indicate that solar cell with CuAgBi2I8 as the absorber layer is a potential alternative to organic–inorganic lead halide perovskite solar cells.

Realizing Long Magnon Diffusion in Organic-Inorganic Hybrid Perovskite Film by the Universal Isotope Effect.

Organic-inorganic halide perovskite (OIHP) spintronics has become a promising research field, as it provides a new precisely manipulable degree of freedom. Recently, by utilizing the spin Seebeck effect and inverse spin-Hall effect measurements, we have discovered substantial magnon injection and transport in Pt/OIHP/Y3Fe5O12 nonlocalized structure. In theory, hyperfine interaction (HFI) is considered to have an important role in the magnon transport of OIHP, but there is no clear experimental evidence reported so far. We report increased spin Seebeck coefficient and lengthened magnon diffusion length in deuterated- (D-) OIHP films that have weaker HFI strength compared with protonated- (H-) OIHP. Consequently, D-MAPbBr3 film, as a non-ferromagnetic spacer, achieves long magnon diffusion length at room temperature (close to 120.3 nm). Our finding provides valuable insights into understanding magnon transport in OIHP films and paves the way for the use of OIHPs in multifunctional applications.

Self-passivation of Halide Interstitial Defects by Organic Cations in Hybrid Lead-Halide Perovskites: Ab Initio Quantum Dynamics.

Halide interstitial defects severely hinder the optoelectronic performance of metal halide perovskites, making research on their passivation crucial. We demonstrate, using ab initio nonadiabatic molecular dynamics simulations, that hydrogen vacancies (Hv) at both N and C atoms of the methylammonium (MA) cation in MAPbI3 efficiently passivate iodine interstitials (Ii), providing a self-passivation strategy for dealing with the Hv and Ii defects simultaneously. Hv at the N site (Hv-N) introduces a defect state into the valence band, while the state contributed by Hv at the C site (Hv-C) evolves from a shallow level at 0 K to a deep midgap state at ambient temperature, exhibiting a high environmental activity. Both Hv-N and Hv-C are strong Lewis bases, capable of capturing and passivating Ii defects. Hv-C is a stronger Lewis base, bonds with Ii better, and exhibits a more pronounced passivation effect. The charge carrier lifetimes in the passivated systems are significantly longer than in those containing either Hv or Ii, and even in pristine MAPbI3. Our demonstration of the Hv and Ii defect self-passivation in MAPbI3 suggests that systematic control of the relative concentrations of Hv and Ii can simultaneously eliminate both types of defects, thereby minimizing charge and energy losses. The demonstrated defect self-passivation strategy provides a promising means for defect control in organic-inorganic halide perovskites and related materials and deepens our atomistic understanding of defect chemistry and charge carrier dynamics in solar energy and optoelectronic materials.

Probing the Impact of Four BSF Layers on MASnI3‐Based Lead‐Free Perovskite Solar Cells for >33% Efficiency

AbstractThis study systematically investigates the impact of various layers of the back surface field (BSF) on the performance of CH₃NH₃SnI₃ (MASnI₃)‐based lead‐free mixed organic–inorganic halide perovskite solar cells. By employing SCAPS‐1D (Solar Cell Capacitance Simulator in One Dimension) simulation software, the behavior of solar cells is analyzed incorporating BSF layers of CuI, NiO, ZnTe, and CBTS. The findings indicate that the inclusion of these BSF materials significantly enhances power conversion efficiency (PCE), with CBTS showing the highest PCE of 33.57%. The energy band diagrams reveal that the BSF layers effectively reduce recombination losses at the rear interface and improve charge carrier collection. Detailed analysis of photovoltaic parameters, such as open‐circuit voltage (Voc), short‐circuit current density (Jsc), fill factor (FF), and overall PCE, underscores the superiority of CBTS as optimal BSF materials. Temperature variation studies demonstrate that CBTS maintains superior performance across a range of temperatures, highlighting its potential for high‐efficiency, thermally stable perovskite solar cells. This comprehensive investigation provides valuable insights for optimizing the design and performance of MASnI₃‐based perovskite solar cells, with the aim of efficiencies greater than 33%.

In-Situ comparative study of photo-induced charge behavior in single-perovskite Cs3Bi2Br9 and double-perovskite Cs2AgBiBr6

While organic-inorganic lead halide perovskites excel in optoelectronic applications, their use is limited by toxicity and degradation. Consequently, lead-free alternatives like Cs2AgBiBr6, offering greater stability and diverse applications, have been investigated. However, the fundamental structural, optical, and electronic properties of Cs2AgBiBr6 remain insufficiently understood. In this study, we compared the exciton dynamics and photo-induced charge separation in Cs3Bi2Br9 and Cs2AgBiBr6 films using in-situ surface techniques. Both materials display similar surface photovoltage (SPV) peaks in the 450–500 nm range, supporting the hypothesis of Bi 6s-6p orbital transitions in distorted [BiBr6]3− structures. Although many theories propose the presence of self-trapped excitons (STE) in bismuth-based perovskites, sufficient evidence has been lacking. Our observation of a significant redshift in the SPV peak compared to the band edge absorption peak supports STE hypothesis, with Cs2AgBiBr6 showing a more pronounced redshift due to its more complex electronic structure and stronger electron-phonon coupling. Additionally, we observed that Cs2AgBiBr6 exhibits superior charge separation efficiency compared to Cs3Bi2Br9. Notably, Cs2AgBiBr6 shows significantly shorter rise times, indicating more rapid photogenerated charge separation. However, both materials exhibit similar fall times, suggesting comparable charge recombination rates. Light-chopping-frequency dependent SPV measurements further reveal that Cs2AgBiBr6 has a higher charge separation rate than Cs3Bi2Br9. These findings underscore the potential of bismuth-based perovskites for optoelectronic applications and highlight the importance of a comprehensive understanding of their structure-property relationships.

Solution-Processed Micro-Nanostructured Electron Transport Layer via Bubble-Assisted Assembly for Efficient Perovskite Photovoltaics.

Organic-inorganic halide perovskite solar cells (PSCs) have attracted significant attention in photovoltaic research, owing to their superior optoelectronic properties and cost-effective manufacturing techniques. However, the unbalanced charge carrier diffusion length in perovskite materials leads to the recombination of photogenerated electrons and holes. The inefficient charge carrier collecting process severely affects the power conversion efficiency (PCE) of the PSCs. Herein, a solution-processed SnO2 array electron transport layer with precisely tunable micro-nanostructures is fabricated via a bubble-template-assisted approach, serving as both electron transport layers and scaffolds for the perovskite layer. Due to the optimized electron transporting pathway and enlarged perovskite grain size, the PSCs achieve a PCE of 25.35% (25.07% certificated PCE).

Observation of Hot Carrier Localization Affected by A Cations in Hybrid Perovskites.

Organic-inorganic lead halide perovskites (OLHPs) have demonstrated exceptional properties in high-performance photoelectric devices. However, the impact of A-site cations, specifically formamidinium and methylammonium (MA), on the optoelectronic properties of OLHPs, particularly in the context of hot carrier utilization, remains a topic of debate. In this study, we propose a method for characterizing hot carrier transportation by measuring the hot carrier mobility and momentum-dependent transient photocurrent influenced by A-site cations in OLHPs. Our findings reveal that the direction of photon drag current is reversed upon substitution of the MA cation, suggesting the strong localization of hot carriers by the MA cation dipole. Furthermore, the correlation between the hot carrier photoconductivity and the electronic structure in different A-site cation samples indicates that hot carrier mobility in OLHPs can be reduced by >50% due to the influence of A-site cations.

Progress of Hole-Transport Layers in Mixed Sn-Pb Perovskite Solar Cells.

Hybrid organic-inorganic lead halide perovskite solar cells (PSCs) have rapidly emerged as a promising photovoltaic technology, with record efficiencies surpassing 26%, approaching the theoretical Shockley-Queisser limit. The advent of all-perovskite tandem solar cells (APTSCs), integrating Pb-based wide-bandgap (WBG) with mixed Sn-Pb narrow-bandgap (NBG) perovskites, presents a compelling pathway to surpass this limit. Despite recent innovations in hole transport layers (HTLs) that have significantly improved the efficiency and stability of lead-based PSCs, an effective HTL tailored for Sn-Pb NBG PSCs remains an unmet need. This review highlights the essential role of HTLs in enhancing the performance of Sn-Pb PSCs, focusing on their ability to mitigate non-radiative recombination and optimize the buried interface, thereby improving film quality. The distinct attributes of Sn-Pb perovskites, such as their lower energy levels and accelerated crystallization rates, necessitate HTLs with specialized properties. In this study, the latest advancements in HTLs are systematically examined for Sn-Pb PSCs, encompassing organic, self-assembled monolayer (SAM), inorganic materials, and HTL-free designs. The review critically assesses the inherent limitations of each HTL category, and finally proposes strategies to surmount these obstacles to reach higher device performance.

Structure Evolution and Optical Tuning of One-Dimensional Post-perovskite (TDMP)PbBr4 under High Pressure.

Optimizing the structure and tuning the optical properties in low-dimensional organic-inorganic halide perovskites are crucial to practical applications for stable solid-state lighting. Herein, we performed high-pressure investigations on one-dimensional (1D) postperovskite (TDMP)PbBr4 (TDMP = trans-2,5-dimethylpiperaziniium), and structure and optical properties under pressure are studied. (TDMP)PbBr4 exhibits color tunable emission from cool white light to yellow orange as the pressure increases from atmospheric pressure to 20.0 GPa. It was found that high pressure would facilitate trapping the free exciton (free exciton) to form a self-trapped exciton (STE) state due to increased electron-phonon interaction, thus enhancing STE emission in the pressure range of 4.0-7.0 GPa. At above 7.0 GPa, the STE emission is quenched, which is due to the phonon-assisted nonradiative relaxation. Meanwhile, (TDMP)PbBr4 displays reversible piezochromism from colorless to yellow under pressure as a result of the compound undergoing a reversible structural transformation. This work provides an insightful perspective on revealing the relationship between structure and optical properties of 1D postperovskites under high pressure.

Effect of bromine on the formation of δ-CsPbI3 in Cs0.22FA0.78Pb(I1-xBrx)3 perovskite solar cells

Applying CsxFA1-xPbI3 perovskite is a useful strategy for synthesizing high-efficiency organic-inorganic lead halide perovskite solar cells because it improves the stability of the perovskite structure. High concentration of cesium (Cs) in CsFAPbI3 synthesized under ambient conditions typically lead to phase separation due to δ-CsPbI3 formation and moisture, thereby reducing light absorption and increasing non-radiative recombination. To counter this, we fabricated the mixed halide Cs0.22FA0.78Pb(I1-xBrx)3 perovskite films. Introducing bromine (Br) content effectively reduced the δ-CsPbI3 formation and grain boundaries, thus suppressing the non-radiative recombination between perovskite and charge transport layers. Employing this approach, our perovskite solar cells with a 10 % Br concentration achieved a power conversion efficiency of 15.81 %. This demonstrates the potential of Br incorporation in enhancing the stability and efficiency of perovskite solar cells.

Interfacial modification by 2-fluoroisonicotinic acid enabling high-efficiency and stable n-i-p perovskite solar cells

The power conversion efficiency (PCE) of organic-inorganic halide perovskite solar cells (PSCs) developed rapidly in recent years. However, the defects at the bulk grain boundaries and heterojunction interfaces acting as non-radiative recombination centres and the ion-migration channels severely hinder the charge transport and stability of the PVKs, resulting in low PCE and poor stability. One of the principal impediments to the commercialization of PSCs resides in the challenge posed by this particular aspect. In this work, we employed 2-fluoroisonicotinic acid (2-FINA) as a passivation agent to improve the PCE and stability of n-i-p PSCs by interfacial modification strategy. Owing to the presence of carboxyl (COOH) functional groups and pyridine groups, 2-FINA can strongly interact with uncoordinated Pb2+ and regulate the growth of perovskite crystals, which in turn reduces ion migration and suppress non-radiative recombination along with improves optical properties. Thanks to these improvements, the champion n-i-p PSC solar cell, treated with 2-FINA, showed a PCE of 20.92 %, whereas the untreated one in the same batch exhibited a PCE of 17.13 %. In long-term stability tests, we demonstrated that 2-FINA treatment significantly increases the moisture resistance of non-encapsulated devices.

Lead-free Cs3Bi2I9 perovskite hexagonal microplates: A promising material solution-processed for ultraviolet self-powered photodetectors

In recent times, hybrid organic-inorganic lead halide perovskites have garnered significant attention in the realm of optoelectronic devices. Metal halide perovskites are extensively researched for photodetection due to their exceptional optical and electrical properties. However, the toxicity of lead and the unstable nature of organic components are limiting its potential. Lead-free perovskites, on the other hand, have low toxicity and are being explored as a promising material for photodetector applications. However, achieving self-powered perovskite photodetectors with high photoresponse, broad spectral sensitivity, and long-term stability remains challenging Among them, Cs3Bi2I9 perovskites have emerged as standout, garnering attention for their environmentally friendly nature, impressive stability, and heightened photosensitivity. Herein, FTO/ Al-doped ZnO (AZO)/Cs3Bi2I9/P3HT/C self-powered ultra-violet (UV) photodetector. This device demonstrated outstanding self-powered photodetection capabilities with a photoresponsivity of 29 mA/W, a specific detectivity of 1.05×1011 Jones, and an impressive response rise and decay time of 90 ms /140 ms. Furthermore, the PDs device can function as a bias-based UV photodetector.

Mapping Spatial Strain Distribution and Its Effects on Optoelectronic Properties in Wrinkled Perovskite Films.

Organic-inorganic halide perovskite films, fabricated by using the antisolvent method, have garnered intense attention for their application in high-efficiency and stable solar cells. These films characteristically develop periodic wrinkled microstructures. Previous research has indicated that macroscopic residual strain significantly influences the optoelectronic behaviors of these films. However, the detailed interplay between the wrinkled morphology, strain distribution, and local photophysical properties at the micro- and nanoscale has not been fully elucidated. Here, we explore the microscopic morphology-strain-property relationship within wrinkled perovskite films employing correlative micro-optical and nanoelectrical microscopy techniques. Microphotoluminescence (PL) mapping supplemented by in situ strain PL measurements identifies a heterogeneous spatial strain distribution across the microstructural hills and valleys. Additionally, light-intensity-dependent photoconductive atomic force microscopy reveals that valleys experiencing less compressive strain exhibit a lower conductivity and a higher propensity for ion migration. The findings underscore the potential of targeted strain engineering to optimize the performance and longevity of perovskite solar cells.

Applications of Hybrid Organic-inorganic Halide Perovskite Materials

Organic-inorganic halide perovskite materials have garnered significant attention in recent years due to their outstanding optoelectronic properties. Initially recognized for their potential in solar energy conversion, their applications have since expanded to include light-emitting diodes, lasers, and semiconductor devices. This article introduce the characteristics of organic-inorganic halide perovskite materials and discusses the recent findings from the Emerging Materials and Device Laboratory, highlighting their various applications in solar cells and semiconductor devices.

Derivative learning of tensorial quantities-Predicting finite temperature infrared spectra from first principles.

We develop a strategy that integrates machine learning and first-principles calculations to achieve technically accurate predictions of infrared spectra. In particular, the methodology allows one to predict infrared spectra for complex systems at finite temperatures. The method's effectiveness is demonstrated in challenging scenarios, such as the analysis of water and the organic-inorganic halide perovskite MAPbI3, where our results consistently align with experimental data. A distinctive feature of the methodology is the incorporation of derivative learning, which proves indispensable for obtaining accurate polarization data in bulk materials and facilitates the training of a machine learning surrogate model of the polarization adapted to rotational and translational symmetries. We achieve polarization prediction accuracies of about 1% for the water dimer by training only on the predicted Born effective charges.

Influence of post-thermal treatment on characteristics of polycrystalline hybrid halide perovskite nanoparticles thin film

A three-dimensional organic–inorganic hybrid halide perovskite (CH3NH3PbI2Br) nanoparticle film was synthesized using solution process in one step. Precursors’ stoichiometry was used to prepare methylammonium bromide and lead (II) bromide in dimethyl formamide. The synthesized CH3NH3PbI2Br solution was spin coated on cleaned ITO prepatterned glass substrate at 2000 rpm. In addition, the influence of post-thermal treatment on the deposited nanoparticles films was evaluated by studying the structural, optical and morphological properties using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectrometry, UV–visible spectrophotometry, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average crystallite sizes were calculated to be ~ 8.0, ~ 9.4, ~ 11.3 and ~ 13.1 nm of as-prepared and annealed films at 400, 500 and 600 °C, respectively. Besides, the bandgaps of 2.22 eV, 1.96 eV, 1.89 eV and 1.63 eV were extrapolated for as-prepared and annealed films at 400 °C, 500 °C and 600 °C, respectively. From J–V curves, the Jsc values of 9.4, 10.6, 11.7 and 12.8 mAcm−2, FF values of 56.99%, 57.25%, 58.94% and 59.26% and PCE values of 2.99%, 3.49%, 3.96% and 4.39% were calculated for as-prepared and annealed CH3NH3PbI2Br films at 400 °C, 500 °C and 600 °C, respectively. The percentage enhancement values of 14.32%, 24.49% and 31.89% compared to as-prepared CH3NH3PbI2Br film. Hence, post-thermal treatment of organic–inorganic halide perovskite material improved its photoconversion efficiency without sacrificing its dimensionality.

In-Situ Growth of One-Dimensional Blocking Layer to Mitigate Deficient Surface of Single-Crystal Perovskites.

Organic-inorganic halide perovskite (OIHP) single crystals are promising for optoelectronic application, but their high surface trap density and associated ion migration hinders device performance and stability. Herein, a one-dimensional (1D) perovskites are designed and proposed as blocking layer at the crystal/electrode interface to mitigate the surface issues. As a model system, the interface ion migration in Cs0.05FA0.95PbI3 (FA=formamidinium) single-crystal perovskite solar cells (PSCs) is obviously suppressed, leading to increase of T90 lifetime from 260 to 1000 hours, five times better than previously reported results. Besides, the reduction of surface iodide ion vacancies inhibits nonradiative recombination, thus increasing the efficiency from 22.1% to 23.8%, which is one of the highest values for single-crystal PSCs. Since the deficient crystal surface is a universal and open issue, our strategy is instructive for optimizing diverse single-crystal perovskite devices.