Search Results (177)

Lead-free A₂ZrX₆ “defect” perovskites hold significant potential for many optoelectronic applications due to their stability and tunable properties. Extending a previous work, we present a first-principles density functional theory (DFT) study, utilizing PBE and HSE06 functionals, to systematically investigate the impact of A-site cation and X-site halogen substitutions on the structural and electronic properties of these materials. We varied the A-site cation, considering ammonium, methylammonium, dimethylammonium, trimethylammonium, and phosphonium, and the X-site halogen, trying Cl, Br, and I. Our calculations reveal that both these substitutions significantly affect the band gap and the lattice parameters. Increasing A-site cation size generally enlarges the unit cell, while halogen electronegativity directly correlates with the band gap, yielding the lowest values for iodine-containing systems. We predict a broad range of band gaps (from ~4.79 eV for (PH₄)₂ZrCl₆ down to ~2.11 eV for MA₂ZrI₆ using HSE06). The (PH₄)₂ZrX₆ compounds maintain cubic crystal symmetry, unlike the triclinic of the ammonium-derived systems. Finally, our calculations show that the MA cation yields the smallest band gap among the ones studied, a result that is attributed to its size and the charges of the hydrogen atoms attached to nitrogen. Thus, our findings offer crucial theoretical insights into A₂ZrX₆ structure–property relationships, demonstrating how A-site cation and halogen tuning enables control over electronic and structural characteristics, thus guiding future experimental efforts for tailored lead-free perovskite design. Full article

Two-dimensional (2D) organic−inorganic hybrid perovskites (OIHPs) have emerged as promising candidates for next-generation optoelectronic applications. While vertical heterostructures of 2D OIHPs have been explored through mechanical stacking, the controlled fabrication of lateral heterostructures remains a significant challenge. Here, we present a lithography-free, van der Waals mask-assisted strategy for the deterministic fabrication of 2D OIHP lateral heterostructures. Mechanically exfoliated 2D materials such as graphene serve as removable masks that enable selective conversion of unmasked perovskite regions via ion exchange reaction. This technique enables the fabrication of various lateral heterostructures, such as BA₂MA₂Pb₃I₁₀/MAPbI₃, PEAPbI₄/MAPbI₃, as well as BA₂MAPb₂I₇/MAPbBr₃. Furthermore, complex multiheterostructures and superlattices can be constructed through sequential masking and conversion processes. Moreover, to investigate the electronic properties and demonstrate potential device applications of the lateral heterostructures, we have fabricated an electrical diode based on a BA₂MA₂Pb₃I₁₀/MAPbI₃ lateral heterostructure. Stable electrical rectifying behavior with a rectification ratio of around 10 was observed. This general and flexible approach provides a robust platform for constructing 2D OIHPs lateral heterostructures and opens new pathways for their integration into high-performance optoelectronic devices. Full article

The one-dimensional (1D) Sb(III)-based organic–inorganic hybrid perovskite (AImd)₂¹_∞[SbI₅] (AImd = 1-allylimidazolium) crystallizes in the orthorhombic, centrosymmetric space group Pnma. The structure consists of corner-sharing [SbI₆] octahedra forming 1D chains separated by allylimidazolium cations. Void analysis through Mercury CSD software confirmed a densely packed lattice with a calculated void volume of 1.1%. Integrated quantum theory of atoms in molecules (QTAIM) and non-covalent interactions index (NCI) analyses showed that C–H···I interactions between the cations and the ¹_∞[SbI₅]²⁻ network predominantly stabilize the supramolecular assembly followed by N–H···I hydrogen bonds. The calculated growth morphology (GM) model fits very well to the experimental morphology. UV–Vis diffuse reflectance spectroscopy allowed us to determine the optical band gap to 3.15 eV. Density functional theory (DFT) calculations employing the B3LYP, CAM-B3LYP, and PBE0 functionals were benchmarked against experimental data. CAM-B3LYP best reproduced Sb–I bond lengths, while PBE0 more accurately captured the HOMO–LUMO gap and the associated electronic descriptors. These results support the assignment of an inorganic-to-organic [Sb–I] → π* charge-transfer excitation, and clarify how structural dimensionality and cation identity shape the material’s optoelectronic properties. Full article

Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have attracted considerable attention in optoelectronic applications, owing to their remarkable characteristics. Nevertheless, the application of 2D HOIPs encounters inherent challenges due to the presence of insulating organic spacers, which create barriers for efficient interlayer charge transport (CT). To tackle this issue, we propose a BA₂MAPb₂I₇/PEA₂MA₂Pb₃I₁₀ bilayer heterostructure, where efficient interlayer energy transfer (ET) facilitates compensation for the restricted charge transport across the organic spacer. Our findings reveal that under 532 nm light illumination, the BA₂MAPb₂I₇/PEA₂MA₂Pb₃I₁₀ heterostructure photodetector exhibits a significant photocurrent enhancement compared with that of the pure PEA₂MA₂Pb₃I₁₀ device, mainly due to the contribution of the ET process. In contrast, under 600 nm light illumination, where ET is absent, the enhancement is rather limited, emphasizing the critical role of ET in boosting device performance. The overlap of the PL emission peak of BA₂MAPb₂I₇ with the absorption spectra of PEA₂MA₂Pb₃I₁₀, alongside the PL quenching of BA₂MAPb₂I₇ and the enhanced emission of PEA₂MA₂Pb₃I₁₀ provide confirmation of the existence of ET in the BA₂MAPb₂I₇/PEA₂MA₂Pb₃I₁₀ heterostructure. Furthermore, the PL enhancement factor followed a 1/d² relationship with the thickness of the hBN layer, indicating that ET originates from 2D-to-2D dipole–dipole coupling. This study not only highlights the potential of leveraging ET mechanisms to overcome the limitations of interlayer CT, but also contributes to the fundamental understanding required for engineering advanced 2D HOIP optoelectronic systems. Full article

In this study, we investigate the influence of the halogen elements bromine (Br) and chlorine (Cl) on iodine defect properties primarily in FAPbI₃ through first-principles calculations, aiming to understand the effect of high defect densities on the efficiency of organic–inorganic hybrid perovskite cells. The results indicate that Br and Cl interstitials minimally alter the overall band structure of FAPbI₃ but significantly modify the defect energy levels. Br and Cl interstitials, with defect states closer to the valence band and lower formation energies, effectively convert deep-level traps induced by iodine interstitials (I_i) into shallow-level traps. This conversion enhances carrier transport by reducing non-radiative recombination while preserving light absorption efficiency. Excess Br/Cl co-doping in FAPbI₃ synthesis thereby suppresses non-radiative recombination and mitigates the detrimental effects of iodide-related defects. Full article

Organic–inorganic hybrid halide perovskites have emerged as promising optoelectronic materials owing to their exceptional optoelectronic properties and versatile crystal structures. The introduction of chiral organic ligands into perovskite frameworks, breaking the inversion symmetry of the structure, has attracted significant attention toward chiral perovskites. Herein, the recent advances in various synthesis strategies for chiral perovskite single crystals (SCs) are systematically demonstrated. Then, we elucidate an in-depth understanding of the chirality transfer mechanisms from chiral organic ligands to perovskite inorganic frameworks. Furthermore, representative examples of chiral perovskite SC-based applications are comprehensively discussed, including circularly polarized light (CPL) photodetection, nonlinear optical (NLO) responses, and other emerging chirality-dependent applications. In the end, an outlook for future challenges and research opportunities is provided, highlighting the transformative potential of chiral perovskites in next-generation optoelectronic devices. Full article

Organic–inorganic hybrid flexible perovskite solar cells (F-PSCs) have garnered considerable interest owing to their exceptional power conversion efficiency (PCE) and stable operational characteristics. However, F-PSCs continue to exhibit significantly lower PCE than their rigid counterparts. Herein, we employed 3-chloro-4-methoxybenzylamine hydrochloride (CMBACl) treatment to grow in situ two-dimensional (2D) perovskite layers on three-dimensional (3D) perovskite films. Through comprehensive physicochemical characterization, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) mapping, we demonstrated that CMBACl treatment enabled the in situ growth of two-dimensional (2D) perovskite layers on three-dimensional (3D) perovskite films via chemical interactions between CMBA⁺ cations and undercoordinated Pb²⁺ sites. The organic cation (CMBA⁺) bound to uncoordinated Pb²⁺ ions and residual PbI₂, while the chlorine anion (Cl⁻) filled iodine vacancies in the perovskite lattice, thereby forming a high-quality 2D/3D heterojunction structure. The CMBACl treatment effectively passivated surface defects in the perovskite films, prolonged charge carrier lifetimes, and enhanced the operational stability of the photovoltaic devices. Additionally, the hybrid 2D/3D architecture also improved energy band matching, thereby boosting charge transfer performance. The optimized flexible devices demonstrated a PCE of 23.15%, while retaining over 82% of their initial efficiency after enduring 5000 bending cycles under a 5 mm curvature radius (R = 5 mm). The unpackaged devices retained 94% of their initial efficiency after 1000 h under ambient conditions with a relative humidity (RH) of 45 ± 5%. This strategy offers practical guidelines for selecting interface passivation materials to enhance the efficiency and stability of F-PSCs. Full article

Single-phase white-light-emitting materials, particularly 2D hybrid organic–inorganic halide perovskites, have garnered significant attention due to their strong electron–phonon interactions, which lead to broad luminescence and a notable Stokes shift resulting from self-trapped exciton recombination. However, 2D lead iodide perovskites typically display these characteristics poorly, restricting their efficiency as white-light emitters. This study presents a 2D lead iodide perovskite that incorporates a fluorinated π-conjugated aggregation-induced enhanced emission luminophore, FPCSA, as a bulky organic cation to create a quasi-2D perovskite. The FPCSA cation establishes a Type II energy level alignment with the lead iodide layer in the 2D perovskite, and a significant energy offset effectively suppresses charge transfer, enabling independent emission from both the organic and inorganic layers while facilitating self-trapped exciton formation. Under 315 nm UV excitation, this material demonstrates warm white-light emission with RGB triple-band photoluminescence stemming from the electronically decoupled FPCSA and perovskite layers. These findings provide a promising new method for designing efficient single-phase white-light-emitting materials for optoelectronic applications. Full article

Hybrid organic–inorganic perovskites have emerged as promising materials for next-generation optoelectronic devices owing to their tunable properties and low-cost fabrication. We report the synthesis of 3D hybrid perovskites with monoethanolammonium cations. Specifically, we investigated the optoelectronic properties and morphological characteristics of polycrystalline films of hybrid perovskites MA_xMEA_1−xPbI₃, which contain methylammonium (MA) and monoethanolammonium (MEA) cations. MA_xMEA_1−xPbI₃ crystallizes in a tetragonal perovskite structure. The substitution of methylammonium cations with monoethanolammonium ions led to an increase in the lattice parameters and the bandgap energy. Energy level diagrams of the synthesized samples were also constructed. The bandgap of MA_0.5MEA_0.5PbI₃ makes it a promising material for use in tandem solar cells. These polycrystalline films, namely MA_0.5MEA_0.5PbI₃ and MA_0.25MEA_0.75PbI₃ were fabricated using a one-step spin-coating method without an antisolvent. These films exhibit a uniform surface morphology under the specified deposition parameters. Within the scope of this study, no evidence of dendritic structures or pinhole-type defects were observed. All synthesized samples demonstrated photocurrent generation under visible light illumination. Moreover, using monoethanolammonium cations reduced the hysteresis of the I–V characteristics, indicating improved device stability. Full article

The research considered in this publication aims to contribute to developing perovskite-based technologies by conducting basic research on perovskite materials. The materials described in the paper are thin films of hybrid perovskite MEAPbI₃ made using the PVco-D method in three different compositions—perovskite samples differ in the percentage of organic methylammonium and inorganic iodide parts. This publication discusses the influence of the composition of the thin perovskite layer on its structural and optical properties and the influence of the temperature of the environment of the perovskite thin film on optical properties. To answer these questions, the surface topography was analyzed using the AFM method, spectroscopic measurements were carried out in the UV-Vis-NIR range, and photoluminescence measurements were performed in a wide temperature range—from about 80 K to 310 K. The results indicate that the composition changes the surface topography, forming increasingly higher crystallites (up to 606%) with increasing methylammonium content. The transition temperature from the orthorhombic to the tetragonal phase was determined for each composition at about 140 K. For the composition of 30% MEAI + 70% PbI2, the phase transition temperature from tetragonal to cubic was determined at a temperature close to RT. Full article

Three-dimensional (3D) hybrid organic–inorganic perovskites (HOIPs) have attracted tremendous interest due to strong excitonic effects and large optical nonlinearities. Taking the advantages, 3D HOIPs show great potential for applications in excitonic and nonlinear devices. However, understanding the relevant mechanisms of exciton-associated nonlinear optical phenomena in 3D perovskites is still challenging. Here, we apply the quantum perturbation theory to calculate the exciton-associated degenerate 2PA spectra of 3D HOIPs. The calculated 2PA spectra of twelve 3D HOIPs are predicted to exhibit resonance peaks at both the sub-band and band edges. The exciton-resonance-associated 2PA coefficients are at least one order of magnitude larger than those of band-to-band transitions and are comparable to those of low-dimensional perovskites. To validate our model, we carried out measurements of the static light-intensity-dependent transmission on MAPbBr₃ single crystals. Enhancements of 2PA coefficients are predicted theoretically and observed experimentally with a resonant peak at 1100 nm, indicating intrinsic two-photon transitions to excitonic states in MAPbBr₃ single crystals. Full article

Memristors are promising candidates for next-generation non-volatile memory devices, offering low power consumption and high-speed switching capabilities. However, conventional metal oxide-based memristors are constrained by fabrication complexity and high costs, limiting their commercial viability. Organic–inorganic hybrid perovskites (OIHPs), known for their facile solution processability and unique ionic–electronic conductivity, provide an attractive alternative. This study presents a conjugated polyelectrolyte (CPE), PhNa-1T, as an interlayer for OIHP memristors to enhance the high-resistance state (HRS) performance. A post-treatment process using n-octylammonium bromide (OABr) was further applied to optimize the interlayer properties. Devices treated with PhNa-1T/OABr achieved a significantly improved ON/OFF ratio of 2150, compared to 197 for untreated devices. Systematic characterization revealed that OABr treatment improved film morphology, reduced crystallite strain, and optimized energy level alignment, thereby reinforcing the Schottky barrier and minimizing current leakage. These findings highlight the potential of tailored interlayer engineering to improve OIHP-based memristor performance, offering promising prospects for applications in non-volatile memory technologies. Full article

Hybrid organohalide perovskites have received considerable attention due to their exceptional photovoltaic (PV) conversion efficiencies in optoelectronic devices. In this study, we report the development of a highly sensitive, self-powered perovskite-based photovoltaic photodiode (PVPD) fabricated by incorporating a poly(amic acid)-polyimide (PAA-PI) copolymer as an interfacial layer between a methylammonium lead iodide (CH₃NH₃PbI₃, MAPbI₃) perovskite light-absorbing layer and a poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) hole injection layer. The PAA-PI interfacial layer effectively suppresses carrier recombination at the interfaces, resulting in a high power conversion efficiency (PCE) of 11.8% compared to 10.4% in reference devices without an interfacial layer. Moreover, applying the PAA-PI interfacial layer to the MAPbI₃ PVPD significantly improves the photodiode performance, increasing the specific detectivity by 49 times to 7.82 × 10¹⁰ Jones compared to the corresponding results of reference devices without an interfacial layer. The PAA-PI-passivated MAPbI₃ PVPD also exhibits a wide linear dynamic range of ~103 dB and fast response times, with rise and decay times of 61 and 18 µs, respectively. The improved dynamic response of the PAA-PI-passivated MAPbI₃ PVPD enables effective weak-light detection, highlighting the potential of advanced interfacial engineering with PAA-PI interfacial layers in the development of high-performance, self-powered perovskite photovoltaic photodetectors for a wide range of optoelectronic applications. Full article

Organic photodetectors (OPDs) have garnered significant attention in fields such as image sensing, health monitoring, and wearable devices due to their exceptional performance. This review summarizes recent research advancements in materials, structures, performance, and applications of narrowband organic photodetectors, hybrid organic–inorganic perovskite photodetectors, flexible organic photodetectors (FOPDs), and photomultiplication type organic photodetectors (PM-OPDs). Organic semiconductors offer substantial potential in optoelectronic devices owing to their low cost, ease of processing, and tunable spectral response. Hybrid perovskite materials extend the spectral response range, FOPDs meet the demands of wearable devices, and PM-OPDs enhance sensitivity, allowing for the detection of weak light signals. Through innovations in materials, structural optimization, and improvements in manufacturing processes, the performance of OPDs has seen significant enhancement. This article also explores the application prospects of these technologies in medical monitoring, optical communications, and image sensing. Full article

Electronic equipment brings great convenience to daily life but also causes a lot of electromagnetic radiation pollution. Therefore, there is an urgent demand for electromagnetic wave-absorbing materials with a low thickness, wide bandwidth, and strong absorption. This work obtained a high-performance electromagnetic wave absorption system by adding conductive carbon spheres (CSs) to the CH₃NH₃PbI₃ (MAPbI₃) absorber. In this system, MAPbI₃, with strong dipole and relaxation polarization, acts dominant to the wave absorber. The carbon spheres provide a free electron transport channel between MAPbI₃ lattices and constructs interfacial polarization loss in MAPbI₃/CS. By regulating the content of CSs, we speculate that this increased effective absorption bandwidth and reflection loss intensity are attributed to the conductive channel of the carbon sphere and the interfacial polarization. As a result, when the mass ratio of the carbon sphere is 7.7%, the reflection loss intensity of MAPbI₃/CS reaches −54 dB at 12 GHz, the corresponding effective absorption bandwidth is 4 GHz (10.24–14.24 GHz), and the absorber thickness is 2.96 mm. This work proves that enhancing conduction loss and interfacial polarization loss is an effective strategy for regulating the properties of dielectric loss-type absorbing materials. It also indicates that organic-inorganic hybrid perovskites have great potential in the field of electromagnetic wave absorption. Full article