Halide Perovskites: A New Era of Solution-Processed Electronics

Dimensional reduction in Cs2AgBiBr6 enables long-term stable Perovskite-based gas sensing

Halide perovskite gas sensors have a low gas detection limit at room temperature, surpassing the performance of traditional metal oxide chemiresistors. However, they are prone to structural decomposition and performance loss due to the lack of coordination unsaturated surface metal ions and sensitivity to environmental factors such as water, oxygen, heat, and light. To address this issue, we present a general strategy: replacing the cation Cs+ in inorganic perovskite Cs2AgBiBr6 with long-chain alkylamines. This modification synthesizes perovskite sensor materials that effectively block moisture and exhibit excellent stability under real-working conditions. The chemiresistors show high sensitivity and stability to CO gas, with (BA)4AgBiBr8 detecting CO at a limit of 20 ppb, maintaining performance after 270 days of continuous exposure to ambient air. The exceptional performance of (BA)4AgBiBr8 is elucidated through density functional theory calculations combined with sum frequency generation spectroscopy, marking a significant breakthrough in halide perovskite-based gas sensing by surpassing the stability and sensitivity of traditional sensors.

Bifunctional 4,5-Diiodoimidazole Interfacial Engineering Enables Simultaneous Defect Passivation and Crystallization Control for High-Efficiency Inverted Perovskite Solar Cells

Despite the rapid efficiency advancement of perovskite solar cells (PSCs), non-radiative recombination at the buried interface between self-assembled monolayers (SAMs) and perovskite remains a critical bottleneck, primarily due to interfacial defects and energy level mismatch. In this study, we demonstrate a bifunctional interlayer engineering strategy by introducing 4,5-diiodoimidazole (4,5-Di-I) at the Me-4PACz/perovskite interface. This approach uniquely addresses two fundamental limitations of SAM-based interfaces: the insufficient defect passivation capability of conventional Me-4PACz due to steric hindrance effects and the poor perovskite wettability on hydrophobic SAM surfaces that exacerbates interfacial voids. The imidazole derivatives not only form strong Pb-N coordination bonds with undercoordinated Pb2+ but also modulate the surface energy of Me-4PACz, enabling the growth of pinhole-free perovskite films with preferential crystal orientation. The champion device with 4,5-Di-I modification achieves a power conversion efficiency (PCE) of 24.10%, with a VOC enhancement from 1.12 V to 1.14 V, while maintaining 91% of initial PCE after 1300 h in N₂ atmosphere (25 °C), demonstrating superior stability under ISOS-L-2 protocols. This work establishes a universal strategy for interfacial multifunctionality design, proving that simultaneous defect suppression and crystallization control can break the long-standing trade-off between efficiency and stability in solution-processed photovoltaics.

Optical Learning and Reconfigurable Logic Utilizing Halide Perovskite Thin Film Transistors

Metal halide perovskites with their superior electronic properties, solution processibility, and scalability, are promising candidates for optoelectronic applications such as solar cells and LEDs. Although of importance for ubiquitous, intelligent electronics, reports on the application of thin film transistors (TFTs) fabricated from perovskites are sparse, primarily due to operational conditions limitations and stability issues. Precise control of composition, microstructure as well as novel chemical treatments have been proposed as solutions to this quandary. Here, a room temperature operational n-type solution-processed Cs0.05(MA0.15FA0.7)Pb(Br0.5I2.4) triple cation transistor enabled using tin-doped indium oxide as source/drain contacts is reported. Optical learning is demonstrated by exploiting the inherent photo response of the perovskite channel and gate bias modulation capability of such perovskite TFT optical pixels. The pixels show modulatable learning and forgetting behavior as demonstrated by the training of alphabets. Noise-free optoelectronic relearning is also demonstrated. Finally, the intelligent transistor is also utilized to demonstrate reconfigurable logic, switchable between 'OR' and 'AND' states, demonstrating the versatility of the halide perovskite pixel.

Architectural Innovations in Perovskite Solar Cells

Meeting future energy demands with sustainable sources like photovoltaics (PV) presents significant land and logistical challenges, which can be mitigated by improving PV power conversion efficiency (PCE) and decentralized solutions like building-integrated photovoltaics and solar-integrated mobility systems (e.g., Unmanned Aerial Vehicles (UAVs)). Metal Halide Perovskites Solar Cells (MH-PSCs) provide a transformative, low-cost solution for high-efficiency PV with diverse compositions, exceptional optoelectronic properties, and low-temperature, solution-based processability. Conventionally the MH-PSCs are fabricated in "p-i-n" or "n-i-p" configuration on glass-Transparent Conductive Oxide (TCO) substrates. While glass-based Perovskite Solar Cells (PSCs) have achieved remarkable efficiencies, their limited scalability, high areal-weight, and mechanical rigidity greatly limit their usage in wearables electronics, BIPVs, and e-mobility applications. Addressing these challenges requires "targeted architectural innovations" in MH-PSCs, tailored to specific applications, to drive their practical deployment forward. This study reviews four innovative PSC architectures-Interdigitated Back Contact (IBC) PSCs, Lateral Configuration (LC) PSCs, Fiber-Shaped (FS) PSCs, and Substrate-Configuration (SC) PSCs-highlighting their design advancements for enhanced efficiency, flexibility, lightweight, and application-specific integration. Importantly, the review discusses the precise engineering required in each layer of these architectural innovations to ensure compatibility, efficient charge transport, durability, and scalability while optimizing performance, while also identifying key challenges and outlining directions for future R&D.

High-Performance Broad-Spectrum UV Photodetectors with Uniform Response: Engineering β-Ga2O3:Si/GaN:Si Heterojunctions via Thermal Oxidation for Optoelectronic Logic Gate and Multispectral Imaging

Developing high-performance, broad-spectrum ultraviolet photodetectors (PDs) with uniform response is crucial for optoelectronic applications like spectral analysis, optoelectronic logic gates, and multispectral imaging. This study constructs n-n type β-Ga2O3:Si/GaN:Si heterojunction PDs using thermal oxidation, combining the advantages of β-Ga2O3:Si and GaN:Si for excellent broad-spectrum response (UV-A to UV-C). A proposed channel model for GaN:Si oxidation includes hole formation, vortex structure development, channel formation, and grain growth, providing a basis for understanding β-Ga2O3:Si/GaN:Si heterojunction formation. Uniform Si doping in the β-Ga2O3 layer, achieved through thermal oxidation, reduces resistivity, enhances the collection of photogenerated carriers from the underlying GaN layer, and hence enhances broad-spectrum response performance. The devices exhibit outstanding uniformity and sensitivity across the UV-A to UV-C range, with a peak responsivity of 2.44 × 104 A W-1 and a photocurrent-to-dark current ratio of 1.3 × 105. Applications include optoelectronic logic gates executing "OR gate" and "AND gate" logic operations with 254 and 365 nm UV light, and a single-pixel multispectral imaging system producing high-contrast, clear "CNU" images with 254, 295, and 365 nm UV light. This research advances the understanding of oxide heterojunction formation and offers a method for developing high-performance, uniformly responsive broad-spectrum UV photodetectors for optoelectronic applications.

Dual-functional silver nanoparticle-enhanced ZnO nanorods for improved reactive oxygen species generation and cancer treatment

Recent advancements in sonodynamic therapy (SDT) for cancer treatment have highlighted the potential of enhancing reactive oxygen species (ROS) generation and improving therapeutic outcomes. This study introduces zinc oxide (ZnO) nanorods (NRs) in situ loaded with silver nanoparticles (ZnO@Ag NRs), designed to optimize ROS production under ultrasound irradiation and offer significant advantages in tumor specificity and biosafety. The transmission electron microscopy and elemental mapping confirmed the consistent size and monodispersed Ag nanoparticle for ZnO@Ag NR. Sonodynamic properties showed that ZnO@Ag NRs produce higher singlet oxygen and hydroxyl radicals under ultrasound. In vitro studies demonstrated excellent biocompatibility and enhanced cell-killing effects of ZnO@Ag NRs on CT-26 cells, while in vivo results confirmed its superior anti-tumor efficacy and biosafety. Furthermore, the ZnO@Ag NRs' antibacterial properties were also confirmed, suggesting additional benefits in treating cancers associated with bacterial infections. Collectively, these findings establish ZnO@Ag NRs as a potent and safe agent for ultrasound-driven cancer therapy.

Crystallization control of Cu(I)-halide via thermal evaporation for improving resistive switching memory performance

CsCu2I3 is considered a promising material for lead-free resistive switching (RS) memory devices due to its low operating voltage, high on/off ratio, and excellent thermal and environmental stability. However, conventional lead-free halide-based RS memory devices typically require solvent-based thin-film formation processes that involve toxic organic and acidic solvents, and the effects of process conditions on device performance are often not fully understood. This study investigates the effect of crystallinity on CsCu2I3-based RS memory devices fabricated via thermal evaporation. Crystallinity increases with higher substrate deposition temperatures but decreases with increasing post-annealing temperatures, leading to film decomposition. At a substrate deposition temperature of 180 °C, without post-annealing, the CsCu2I3-based device demonstrates enhanced performance, including an endurance of 190 cycles and a retention time of 6500 s. The devices operate through a space-charge-limited conduction mechanism, as shown by logarithmic I-V characteristics. Trap density calculations reveal that higher crystallinity reduces defects, leading to improved endurance and retention by promoting the formation of stable conductive filaments. This study establishes a relationship between crystallinity and the enhanced endurance and retention of CsCu2I3-based RS memory devices prepared using thermal evaporation as a function of deposited substrate temperature and post-annealing temperature.

Mechanically Resilient and Highly Efficient Flexible Perovskite Solar Cells with Octylammonium Acetate for Surface Adhesion and Stress Relief

Flexible perovskite solar cells (FPSCs) have advanced significantly because of their excellent power-per-weight performance and affordable manufacturing costs. The unsatisfactory efficiency and mechanical stability of FPSCs are bottleneck challenges that limit their application. Here, we explore the use of octylammonium acetate (OAAc) with a long, intrinsic, flexible molecular chain on perovskite films for surface adhesion and mechanical releasing. The results showed that OAAc with high structural flexibility and strong molecular interactions can act as a mechanical release layer in releasing residual tensile stress, confirmed by the film and device characterizations as well as finite-element simulation. Moreover, the passivation of the OAAc could increase the formation energy of defects including I vacancy, Pb vacancy, and Pb-I antisite. The experimental results showed that the trap states of perovskites were significantly suppressed after OAAc modification, which is beneficial to the construction of high-quality films. With a high open-circuit voltage of 1.196 V, the efficiency of the OAAc-treated devices increased from 23.14% to 25.47% on a rigid substrate (23.12% on a flexible substrate), yielding superior long-term and mechanical durability. The corresponding flexible device retains 74% of the initial value even after 8000 bending cycles at a bending radius of 5 mm.

Convergence of nanotechnology and artificial intelligence in the fight against liver cancer: a comprehensive review

Liver cancer is one of the most challenging malignancies, often associated with poor prognosis and limited treatment options. Recent advancements in nanotechnology and artificial intelligence (AI) have opened new frontiers in the fight against this disease. Nanotechnology enables precise, targeted drug delivery, enhancing the efficacy of therapeutics while minimizing off-target effects. Simultaneously, AI contributes to improved diagnostic accuracy, predictive modeling, and the development of personalized treatment strategies. This review explores the convergence of nanotechnology and AI in liver cancer treatment, evaluating current progress, identifying existing research gaps, and discussing future directions. We highlight how AI-powered algorithms can optimize nanocarrier design, facilitate real-time monitoring of treatment efficacy, and enhance clinical decision-making. By integrating AI with nanotechnology, clinicians can achieve more accurate patient stratification and treatment personalization, ultimately improving patient outcomes. This convergence holds significant promise for transforming liver cancer therapy into a more precise, individualized, and efficient process. However, data privacy, regulatory hurdles, and the need for large-scale clinical validation remain. Addressing these issues will be essential to fully realizing the potential of these technologies in oncology.

Fine-tuning of optical band gap in mixed halide aziridinium lead perovskites

Hybrid halide perovskites form a promising class of light-absorbing materials. Among the numerous 3D semiconducting perovskites, there is a group of emerging aziridinium-based hybrids that are considered to be prospective materials for optoelectronic applications. In this work, we report the mixed halide aziridinium perovskites of (AzrH)PbBrxI3-x series (AzrH = aziridinium). Small changes in the composition of perovskites are shown to have a defining impact on the optoelectronic properties of the reported materials. Halogen substitution allowed a variation in band gap values of these compounds, ranging from 1.57 to 2.23 eV, as established using electronic spectroscopy. Crystal structures of (AzrH)PbBrxI3-x perovskites were studied using single crystal and powder X-ray diffraction analysis. The lattice constant had a linear dependence on the Br content in the structure, thus strictly following Vegards's law. Importantly, the reported compounds displayed a preferential inclusion of iodine upon synthesis, revealing that the mixed halide perovskite composition cannot be estimated based on the precursors' ratio only, and it should be post-synthetically checked. The reported results expand the range of hybrid perovskites with tuneable band gaps beyond the conventional methylammonium and formamidinium-based perovskites and offer a new series of metal-halide hybrids suitable for photovoltaic and other optoelectronic applications.

Advances in Heavy Metal Sensing: Utilizing Immobilized Chromogenic Reagents, Nanomaterials Perovskite and Nanonzymes

Heavy metal pollution is a major environmental and health problem due to the toxicity and persistence of metals such as lead, mercury, cadmium, and arsenic in water, soil, and air. Advances in sensor technology have significantly improved the detection and quantification of heavy metals, providing real-time monitoring and mitigation tools. This review explores recent developments in heavy metal detection, focusing on innovative uses of immobilized chromogenic reagents, nanomaterials, perovskites, and nanozymes. Immobilized chromogenic reagents, with their high specificity and visual detection capabilities, provide cost effective solutions for heavy metal detection. Techniques to improve their stability and sensitivity, including surface modifications and hybrid materials, are discussed. Nanomaterials, including quantum dots, metal-organic frameworks, and carbon-based nanostructures, have emerged as versatile platforms due to their unique physicochemical properties. These materials enable highly sensitive and selective sensing mechanisms, such as fluorescence quenching and electrochemical sensing. Perovskites, a class of materials known for their tunable optoelectronic properties, have shown great promise in the optical and electrochemical detection of heavy metals. Despite challenges related to stability and environmental safety, their potential for low-cost and scalable applications is remarkable. Nanozymes, synthetic enzyme mimics, offer robust and catalytic sensing capabilities, particularly in colorimetric and electrochemical analyses. Their superior stability and reusability compared to natural enzymes make them ideal candidates for environmental monitoring. This review provides a comparative analysis of these techniques, highlighting their strengths, limitations, and real-world applicability. Emerging trends include hybrid systems that combine the benefits of multiple approaches. The discussion concludes by addressing current challenges and providing perspectives on future directions for advancing heavy metal detection technologies to improve environmental health and safety. Integrating chromogenic reagents with perovskite materials represents a promising direction for developing robust, sensitive, and easy-to-use sensors for health and environmental safety monitoring.

Crystal structure and Hirshfeld surface analysis of the layered hybrid metal halide poly[bis-(2-iodoethyl-ammonium) [di-μ-iodido-di-iodido-germanate(II)]]

The title compound is a germanium-based hybrid metal halide that represents a less-toxic alternative to more popular lead-based analogues in optoelectronic applications. {(2-IC2H4NH3)2[GeI4]} n is composed of infinite inorganic layers that are formed by [GeI6]4- octa-hedra connected in a corner-sharing manner with four equatorial I atoms. The organic (2-IC2H4NH3)+ cations inter-leave the inorganic layers. There are two types of 2-iodo-ethyl-ammonium cations, with synclinal and anti-periplanar conformations. The organic cations inter-act with the inorganic layers through hydrogen bonds and I⋯I contacts. The crystal under investigation was twinned by a 180° rotation around [100].

Ion Migration at Metal Halide Perovskite Grain Boundaries Elucidated with a Machine Learning Force Field

Metal halide perovskites are promising optoelectronic materials with excellent defect tolerance in carrier recombination, believed to arise largely from their unique soft lattices. However, weak lattice interactions also promote ion migration, leading to serious stability issues. Grain boundaries (GBs) have been experimentally identified as the primary migration channels, but the relevant mechanism remains elusive. Using molecular dynamics with a machine learning force field, we directly model ion migration at a common CsPbBr3 GB. We demonstrate that the as-built GB model, containing 6400 atoms, experiences structural reconstruction over several nanoseconds, and only Br atoms diffuse after that. A fraction of Br atoms near the GB either migrate toward the GB center or along the GB through different migration channels. Increasing the temperature not only accelerates the ion migration via the Arrhenius activation but also allows more Br atoms to migrate. The activation energies are much lower at the GB than in the bulk due to large-scale structural distortions and favorable non-stoichiometric local environments available at GBs. Making the local GB composition more stoichiometric by doping or annealing can suppress the ion migration. The reported results provide valuable atomistic insights into the GB properties and ion migration in metal halide perovskites.

Crystal structure and Hirshfeld surface analysis of the salt 2-iodo-ethyl-ammonium iodide - a possible side product upon synthesis of hybrid perovskites

The title organic-inorganic hybrid salt, C2H7IN+·I-, is isotypic with its bromine analog, C2H7BrN+·Br- [Semenikhin et al. (2024 ▸). Acta Cryst. E80, 738-741]. Its asymmetric unit consists of one 2-iodo-ethyl-ammonium cation and one iodide anion. The NH3 + group of the organic cation forms weak hydrogen bonds with four neighboring iodide anions, leading to the formation of supra-molecular layers propagating parallel to the bc plane. Hirshfeld surface analysis reveals that the most important contribution to the crystal packing is from N-H⋯I inter-actions (63.8%). The crystal under investigation was twinned by a 180° rotation around [001].

Preparation and Properties Study of CsPbX3@PMMA Luminescent Resin

Perovskite as an emerging semiconductor luminescent material has attracted widespread attention due to its simple preparation, high luminescence quantum yield, high color purity, tunable spectrum, and ability to cover the entire visible light band. However, due to the influence of water or other highly polar solvents, oxygen, temperature, and radiation, perovskite nanocrystals will aggregate or collapse in the lattice, eventually leading to luminescence quenching. This study starts from the postprocessing of perovskite, uses methyl methacrylate as the monomer and TPO as the photoinitiator, and encapsulates the perovskite powder prepared by the hot injection method through ultraviolet light initiation. A method is proposed to improve the luminescence and crystal structure stability of perovskite. By eliminating the influence of environmental factors on perovskite nanocrystals through the dense structure formed by organic polymers, the resistance of perovskite to strong polar solvents such as water will be greatly improved, and it has great potential in the protection of perovskite. Finally, by changing the proportion of halogen elements in the perovskite resin to change the color of the luminescent resin, a fluorescent coating emitting light in all visible light bands is prepared. Fluorescent coatings are widely used in life and industry fields such as plastics, sol, and paper.

Rapid Recovery of Degraded Perovskite Single-Crystal Radiation Detectors via Infrared Healing

Radiation detectors based on metal halide perovskite (MHP) single crystals (SCs) have exhibited exceptional sensitivity, low detection limit, and remarkable energy resolution. However, the operational stability issue still dramatically impedes their commercialization due to degradation induced by high-energy irradiation and large bias. Here, we propose an innovative infrared healing strategy to restore the devices that have undergone severe damage from both long-term biasing and X-ray irradiation. Compared to the slow and inefficient intrinsic self-healing process of MHPs, the infrared healing method demonstrates the capacity to achieve rapid recovery of the detection performance of the degraded devices within just 1 h. We reveal that the healing mechanism is mainly related to the reduction of the ion-migration activation energy in MHP SCs under infrared illumination, which promotes the back diffusion of the displaced ions to their original lattice positions and remedies defects. Finally, the healing effect is further confirmed through the gamma-ray spectroscopy acquisition with degraded MHP SCs, whose energy resolution at 59.5 keV of 241Am source is improved from 36% to 12% following infrared illumination. These results present infrared healing as a simple and economic method to extend the service life of MHP SC-based detectors.

Sustainable Mixed-Halide Perovskite Resistive Switching Memories Using Self-Assembled Monolayers as the Bottom Contact

The complex ionic-electronic conduction in mixed halide perovskites enables their use beyond von Neumann architectures implemented in resistive switching memory devices. Although device fabrication based on perovskite compounds involves solution-processing at low temperatures, reducing further fabrication costs by eliminating expensive materials can improve their compatibility with upscalable deposition techniques. Notably, the substrate on which the perovskite active layer is developed has been reported to severely affect its quality and thus the overall device performance. Hereby, we demonstrate the sustainable manufacturing of memristive perovskite solar cells by replacing the expensive poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) that serves as a hole transporting layer (HTL) with a self-assembled monolayer (SAM), namely [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz). Multiple sequential memristive current-voltage characteristics of single devices are reported, and average data of multiple reference and targeted devices are compared. Resistive switching memory devices based on SAM exhibit improved performance having reduced average SET voltage values and narrower statistical variation compared to reference devices with PTAA. It is shown that both PTAA and SAM based devices exhibit high ON/OFF ratio of about 103 operating at low switching electric fields. Replacing an expensive polymer-based HTL with this approach reduces fabrication costs compared to PTAA.

Thermally and Mechanically Stable Perovskite Artificial Synapse as Tuned by Phase Engineering for Efferent Neuromuscular Control

The doping of perovskites with mixed cations and mixed halides is an effective strategy to optimize phase stability. In this study, we introduce a cubic black phase perovskite CsyFA(1-y)Pb(BrxI(1-x))3 artificial synapse, using phase engineering by adjusting the cesium-bromide content. Low-bromine mixed perovskites are suitable to improve the electric pulse excitation sensitivity and stability of the device. Specifically, the low-bromine and low-cesium mixed perovskite (x = 0.15, y = 0.22) annealed at 373 K allows the device to maintain logic response even after 1000 mechanical flex/flat cycles. The device also shows good thermal stability up to temperatures of 333 K. We have demonstrated reflex-arc behavior with MCMHP synaptic units, capable of making sensory warnings at high frequency. This compositionally engineered, dual-mixed perovskite synaptic device provides significant potential for perceptual soft neurorobotic systems and prostheses.

Precursor Engineering Induced High-Efficiency Electroluminescence of Quasi-Two-Dimensional Perovskites: A Synergistic Defect Inhibition and Passivation Approach

Despite light-emitting diodes (LEDs) based on quasi-two-dimensional (Q-2D) perovskites being inexpensive and exhibiting high performance, defects still limit the improvement of electroluminescence efficiency and stability by causing nonradiative recombination. Here, an organic molecule, 1-(o-tolyl) biguanide, is used to simultaneously inhibit and passivate defects of Q-2D perovskites via in situ synchronous crystallization. This molecule not only prevents surface bromine vacancies from forming through hydrogen bonding with the bromine of intermediaries but also passivates surface defects through its interaction with uncoordinated Pb. Via combination of defect inhibition and passivation, the trap density of Q-2D perovskite films can be significantly reduced, and the emission efficiency of the film can be improved. Consequently, the corresponding LED shows an external quantum efficiency of 24.3%, and its operational stability has been increased nearly 15 times.

Multifunctional two-dimensional perovskite based solar cells for photodetectors and resistive switching

The escalating interest in low-dimensional perovskites stems from their tunable optoelectronic traits and robust stability. The pursuit of multifaceted optoelectronic devices holds substantial importance for energy-efficient and space-constrained systems. This investigation showcases the realization of multifunctional two-dimensional perovskite solar cells, incorporating transient light detection and resistive switching functions within a single device, achievable by facile external bias adjustments. Serving as a photodetector, the device exhibits commendable self-powered photodetection attributes, including an exceptionally low dark current density of 1 nA mm-2, a remarkable specific detectivity of 7.67 × 1012 Jones, a swift response time of 0.60 μs, and an expansive linear dynamic range of 72 dB. As a memristor, it showcases enduring performance across 4 × 102 cycles, a substantial on/off ratio of 106, and a rapid operation time of less than 1 μs. This endeavor unveils a pioneering avenue for advancing high-performance, air-stable multifunctional two-dimensional perovskite electronics.

Self-energy correction and numerical simulation for efficient lead-free double perovskite solar cells

Inorganic double perovskites have garnered significant attention due to their desirable characteristics, such as low-toxicity, stability and long charge-carrier lifetimes. However, most double perovskites, especially Cs2AgBiBr6, have wide bandgaps, which limits power conversion efficiencies. In this work, through the first principles method corrected by self-energy, we investigate the mechanical, electric and optical properties of Cs2B'B''Br6 (B' = Ag, Au, Cu; B'' = Bi, Al, Sb, In). Based on performance screening, three kinds of materials with good toughness, high carrier mobility and wide visible-light absorption (around 105 cm-1) are obtained, which are compared with Cs2AgBiBr6. Meanwhile, we use a SACPS-1D simulation to design lead-free double perovskites with excellent properties suitable for photovoltaic solar cell devices, which are made into a planar perovskite heterojunction. Ultimately, the optimal structure is determined to be FTO/WS2/Cs2CuBiBr6/spiro-OMeTAD/Ag, which achieves a power conversion efficiency of 14.08%, surpassing the conventional structure efficiency of 6.1%. It provides valuable guidance for the structure design of a lead-free double perovskite device and offers new insights into the development of optoelectronic devices for solar energy utilization.

Enhancing Visible-Light Absorption of 2D Carbon Nitride by Constructing 2D/2D van der Waals Heterojunctions of Carbon Nitride/Nitrogen-Superdoped Graphene

Carbon nitride sheets (CNs) down to the two-dimensional (2D) limit have been widely used in photoelectric conversion due to their inherent band gap and extremely short charge-carrier diffusion distance. However, the utilization of visible light remains low due to the rapid recombination of photogenerated electron-hole pairs and enlarged band gap. Here, atomically thin 2D/2D van der Waals heterojunctions (vdWHs) of N-superdoped graphene (NG) and CNs (CNs/NG) are fabricated via a facile electrostatic self-assembly method. Our results revealed that the vdWHs can increase the visible-light absorption of CNs by extending the absorption edge from 455 to up to 490 nm. The recombination of photogenerated electron-hole pairs is inhibited because superdoped N in CNs/NG facilitates the transmission of photogenerated carriers in the melon chain. This study opens a new avenue for narrowing the band gap and promoting photoexcited carrier separation in carbon-nitride-based materials.

Local modulation of Au/MoS2 Schottky barriers using a top ZnO nanowire gate for high-performance photodetection

Schottky junctions are commonly used for fabricating heterojunction-based 2D transition metal dichalcogenide (TMD) photodetectors, characteristically offering a wide detection range, high sensitivity and fast response. However, these devices often suffer from reduced detectivity due to the high dark current, making it challenging to discover a simple and efficient universal way to improve the photoelectric performances. Here, we demonstrate a novel approach for integrating ZnO nanowire gates into a MoS2-Au Schottky junction to improve the photoelectric performances of photodetectors by locally controlling the Schottky barrier. This strategy remarkably reduces the dark current level of the device without affecting its photocurrent and the Schottky detectivity can be modified to a maximum detectivity of 1.4 × 1013 Jones with -20 V NG bias. This work provides potential possibilities for tuning the band structure of other materials and optimizing the performance of heterojunction photodetectors.

Polymer-enhanced perovskite oxide-based photocatalysts: a review

Oxide perovskites (OPs) have emerged as promising photocatalysts for numerous applications, such as energy conversion, renewable fuels, and environmental remediation. Although OPs are gaining traction, their efficacies are still hindered by low charge carrier mobility and poor stability. This study investigated the function of polymers actively participating in OP structures to improve the overall characteristics. An overview of the polymer-enhanced perovskite oxide photocatalyst (PEPOP) field was effectively reviewed. These PEPOPs were demonstrated in photovoltaics, pollutant degradation, and gas conversion and reduction. Nonetheless, additional research is needed to explore the potential of PEPOPs to establish their efficacy in photocatalytic applications. The technological improvements of PEPOPs were hindered by significant challenges related to stability and sensitivity. The urgency of this review was apparent due to the fast-paced nature of research in the field of photocatalysis. Recent breakthroughs and emerging applications highlight the need for a comprehensive overview of PEPOPs and their enhanced catalytic capabilities. Consequently, a broad outlook was provided for the current state of PEPOP-related studies, highlighting the potential of these materials for future applications.

Controlled Synthesis of Lead-Free Double Perovskite Colloidal Nanocrystals for Nonvolatile Resistive Memory Devices

Although lead-free double perovskites such as Cs2AgBiBr6 have been widely explored, they still remain a daunting challenge for the controlled synthesis of lead-free double perovskite nanocrystals with highly tunable morphology and band structure. Here, we report the controlled synthesis of lead-free double perovskite colloidal nanocrystals including Cs2AgBiBr6 and Cs2AgInxBi1-xBr6 via a facile wet-chemical synthesis method for the fabrication of high-performance nonvolatile resistive memory devices. Cs2AgBiBr6 colloidal nanocrystals with well-defined cuboidal, hexagonal, and triangular morphologies are synthesized through a facile wet-chemical approach by tuning the reaction temperature from 150 to 190 °C. Further incorporating indium into Cs2AgBiBr6 to synthesize alloyed Cs2AgInxBi1-xBr6 nanocrystals not only can induce the indirect-to-direct bandgap transition with enhanced photoluminescence but also can improve its structural stability. After optimizing the active layers and device structure, the fabricated Ag/polymethylene acrylate@Cs2AgIn0.25Bi0.75Br6/ITO resistive memory device exhibits a low power consumption (the operating voltage is ∼0.17 V), excellent cycling stability (>10 000 cycles), and good synaptic property. Our study would enable the facile wet-chemical synthesis of lead-free double perovskite colloidal nanocrystals in a highly controllable manner for the development of high-performance resistive memory devices.

Lung Toxicity and Molecular Mechanisms of Lead-Based Perovskite Nanoparticles in the Respiratory System

Lead-based perovskite nanoparticles (Pb-PNPs) have found extensive applications across diverse fields. However, because of poor stability and relatively strong water solubility, the potential toxicity of Pb-PNPs released into the environment during their manufacture, usage, and disposal has attracted significant attention. Inhalation is a primary route through which human exposure to Pb-PNPs occurs. Herein, the toxic effects and underlying molecular mechanisms of Pb-PNPs in the respiratory system are investigated. The in vitro cytotoxicity of CsPbBr3 nanoparticles in BEAS-2B cells is studied using multiple bioassays and electron microscopy. CsPbBr3 nanoparticles of different concentrations induce excessive oxidative stress and cell apoptosis. Furthermore, CsPbBr3 nanoparticles specifically recruit the TGF-β1, which subsequently induces epithelial-mesenchymal transition. In addition, the biodistribution and lung toxicity of representative CsPbBr3 nanoparticles in ICR mice are investigated following intranasal administration. These findings indicate that CsPbBr3 nanoparticles significantly induce pulmonary inflammation and epithelial-mesenchymal transition and can even lead to pulmonary fibrosis in mouse models. Above findings expose the adverse effects and molecular mechanisms of Pb-PNPs in the lung, which broadens the safety data of Pb-PNPs.

Tailoring the Electron and Hole Landé Factors in Lead Halide Perovskite Nanocrystals by Quantum Confinement and Halide Exchange

The tunability of the optical properties of lead halide perovskite nanocrystals makes them highly appealing for applications. Halide anion exchange and quantum confinement enable tailoring of the band gap. For spintronics, the Landé g-factors of electrons and holes are essential. Using empirical tight-binding and k·p methods, we calculate them for nanocrystals of all-inorganic lead halide perovskites CsPbX3 (X = I, Br, Cl). The hole g-factor band gap dependence follows the universal law found for bulk perovskites, while for electrons, a considerable modification is predicted. Based on the k·p analysis, we conclude that this difference arises from the interaction of the bottom conduction band with the spin-orbit split electron states. These predictions are confirmed experimentally for electron and hole g-factors in CsPbI3 nanocrystals in a glass matrix, measured by time-resolved Faraday ellipticity in a magnetic field at cryogenic temperatures.

Regulating buried interface properties and alleviating micro-strain of crystals for efficient perovskite solar cells

Surface properties of SnO2 and their effects on the growth of perovskite films play a crucial role for perovskite solar cells (PSCs). Herein, a facile strategy to synchronously regulate the buried interface defects and energy level arrangement, as well as improve the crystallinity of perovskite films with alleviated micro-strain by pre-modifying the SnO2 surface with ammonium hexafluorophosphate (NH4PF6) is proposed. The device achieved the promising PCE of 22.50% and improved stability.

Solvent-antisolvent interactions in metal halide perovskites

The fabrication of metal halide perovskite films using the solvent-engineering method is increasingly common. In this method, the crystallisation of the perovskite layer is triggered by the application of an antisolvent during the spin-coating of a perovskite precursor solution. Herein, we introduce the current state of understanding of the processes involved in the crystallisation of perovskite layers formed by solvent engineering, focusing in particular on the role of antisolvent properties and solvent-antisolvent interactions. By considering the impact of the Hansen solubility parameters, we propose guidelines for selecting the appropriate antisolvent and outline open questions and future research directions for the fabrication of perovskite films by this method.

Morphology-Dependent Charge Carrier Dynamics and Ion Migration Behavior of CsPbBr3 Halide Perovskite Quantum Dot Films

Exceptional electronic, optoelectronic, and sensing properties of inorganic Cs-based perovskites are significantly influenced by the defect chemistry of the material. Although organic halide perovskites that have a polycrystalline structure are heavily studied, understanding of the defect properties at the grain boundaries (GB) of inorganic Cs-based perovskite quantum dots (QDs) is still limited. Here, morphology-dependent charge carrier dynamics of CsPbBr₃ quantum dots at the nanoscale by performing scanning probe microscopy of thermally treated samples are investigated. The grain boundaries of defect-engineered samples show higher surface potential than the grain interiors under light illumination, suggesting an effective role of GBs as charge collection and transport channels. The lower density of crystallographic defects and lower trap density at GBs specifically of heat-treated samples cause insignificant dark current, lower local current hysteresis, and higher photocurrent, than the control samples. It is also shown that the decay rate of surface photovoltage of the heated sample is quicker than the control sample, which implies a considerable impact of ion migration on the relaxation dynamic of photogenerated charge carriers. These findings reveal that the annealing process is an effective strategy to control not only the morphology but also the optoelectrical properties of GB defects, and the dynamic of ion migration. Understanding the origin of photoelectric activity in this material allows for designing and engineering optoelectronic QD devices with enhanced functionality.

Porous and Water Stable 2D Hybrid Metal Halide with Broad Light Emission and Selective H2 O Vapor Sorption

In this work we report a strategy for generating porosity in hybrid metal halide materials using molecular cages that serve as both structure-directing agents and counter-cations. Reaction of the [2.2.2] cryptand (DHS) linker with Pb^II in acidic media gave rise to the first porous and water-stable 2D metal halide semiconductor (DHS)₂ Pb₅ Br₁₄ . The corresponding material is stable in water for a year, while gas and vapor-sorption studies revealed that it can selectively and reversibly adsorb H₂ O and D₂ O at room temperature (RT). Solid-state NMR measurements and DFT calculations verified the incorporation of H₂ O and D₂ O in the organic linker cavities and shed light on their molecular configuration. In addition to porosity, the material exhibits broad light emission centered at 617 nm with a full width at half-maximum (FWHM) of 284 nm (0.96 eV). The recorded water stability is unparalleled for hybrid metal halide and perovskite materials, while the generation of porosity opens new pathways towards unexplored applications (e.g. solid-state batteries) for this class of hybrid semiconductors.

4,4'-(Anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) Lead Iodide C30H22N2Pb2I6: A Highly Luminescent, Chemically and Thermally Stable One-Dimensional Hybrid Iodoplumbate

A new one-dimensional hybrid iodoplumbate, namely, 4,4'-(anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) lead iodide C₃₀H₂₂N₂Pb₂I₆ (AEPyPbI), is reported here for the first time with its complete characterization. The material exhibits remarkable thermal stability (up to 300 °C), and it is unreactive under ambient conditions toward water and atmospheric oxygen, due to the quaternary nature of the nitrogen atoms present in the organic cation. The cation exhibits strong visible fluorescence under ultraviolet (UV) irradiation, and when its iodide is combined with PbI₂, it forms AEPyPb₂I₆, an efficient light-emitting material, with a photoluminescence emission intensity comparable to that of high-quality InP epilayers. The structure determination was obtained using three-dimensional electron diffraction, and the material was extensively studied by using a wide range of techniques, such as X-ray powder diffraction, diffuse reflectance UV-visible spectroscopy, thermogravimetry-differential thermal analysis, elemental analysis, Raman and infrared spectroscopies, and photoluminescence spectroscopy. The emissive properties of the material were correlated with its electronic structure by using state-of-the-art theoretical calculations. The complex, highly conjugated electronic structure of the cation interacts strongly with that of the Pb-I network, giving rise to the peculiar optoelectronic properties of AEPyPb₂I₆. The material, considering its relatively easy synthesis and stability, shows promise for light-emitting and photovoltaic devices. The use of highly conjugated quaternary ammonium cations may be useful for the development of new hybrid iodoplumbates and perovskites with optoelectronic properties tailored for specific applications.

Uncovering Aging Chemistry of Perovskite Precursor Solutions and Anti-aging Mechanism of Additives

The aging of precursor solutions is the major stumbling block for the commercialization of perovskite solar cells (PSCs). Herein, for the first time we used the state-of-the-art in situ liquid time-of-flight secondary ion mass spectrometry to molecularly explore the perovskite precursor solution chemistry. We identified that the methylammonium and formamidinium cations and the I^- anion are the motivators of the aging chemistry. Further, we introduced two kinds of Lewis bases, triethyl phosphate (TP) and ethyl ethanesulfonate (EE), as new additives in the solution and unraveled that both of them can protect the reactive cations from aging through weak interactions. Significantly, TP is superior to EE in enhancing long-term solution stability as it can well-maintain the internal interaction structures within the solution phase. The PSC derived from a fresh TP-doped solution delivered a high power conversion efficiency of 23.06 %, 92.23 % of which remained in that from a 21-day-old solution.

Modulation of the Excitation States in All-Inorganic Halide Perovskites via Sb3+ and Bi3+ Codoping

Sb³⁺-doped halide perovskites are promising candidates for solid-state lighting due to their diverse fluorescent colors and high efficiency. However, the mismatched high excitation energy with commercial UV chips is one of the critical issues to be addressed. Herein, a Bi³⁺ codoping strategy was established as a general and efficient approach to modulate the excitation spectrum from the Sb³⁺-doping center in all-inorganic perovskites of Cs₂InCl₅·H₂O, Cs₂NaInCl₆, and Rb₃InCl₆. The incorporated Bi³⁺ greatly enhanced the splitting of the A band (¹S₀-³P₁ transition) and boosts the enormous redshift of the low-energy branch in all these systems. The interactions persist strongly even at extremely low doping concentrations, suggesting a dipole-based long-range interaction. The results provide an in-depth insight into the contribution mechanism of Bi³⁺ to Sb³⁺ in all-inorganic perovskites, which throws light upon tuning the excitation spectrum of broadband emission from the extrinsic self-trapped exciton (STE).

Go beyond the limit: Rationally designed mixed-dimensional perovskite/semiconductor heterostructures and their applications

Halide perovskite heterojunctions rationally integrate the chemical and physical properties of multi-dimensional perovskites and judiciously chosen semiconductor materials, offering the promise of going beyond the limit of a single component. This emerging platform of materials innovation offers fresh opportunities to tune material properties, discover interesting phenomena, and enable novel applications. In this review, we first discuss the fundamentals of forming heterojunctions with perovskites and a wide range of semiconductors, and then we give an overview of the research progress of halide perovskite heterojunctions in terms of their optical, electrical, and mechanical properties, focusing on how the heterojunction tunes the energy band structure, electrical transport, and charge recombination behaviors. We further outline the progress of perovskite-based heterojunctions in optoelectronics. Finally, the challenges and future research directions for perovskite/semiconductor heterojunctions are discussed.

Two-Terminal Nonvolatile Write-Once-Read-Many-Times Memory Based on All-Inorganic Halide Perovskite

Write-once-read-many-times (WORM) memory belonging to an important non-volatile memory type achieves the read-only state after the write operation and is used in the fields of data security storage widely. WORM memory has been developed based on a variety of materials. In recent years, halide perovskites have become the research hotspot material for this memory due to its excellent properties. Here, the all-inorganic CsPbBr₃ perovskite thin film was prepared on a FTO substrate by using a two-step method. The prepared CsPbBr₃ thin films have the characteristics of densely packed crystal grains and smooth surface. The device, having the FTO/CsPbBr₃/Al sandwich structure by evaporating the Al electrode onto the CsPbBr₃ thin film, represents the typical WORM behavior, with long data retention time (10⁴ s), a low operation voltage (2.1 V) and a low reading voltage (0.1 V). Additionally, the resistance transition mechanism of the resulting WORM devices was analyzed.

Inorganic Halide Perovskite Quantum Dots: A Versatile Nanomaterial Platform for Electronic Applications

Metal halide perovskites have generated significant attention in recent years because of their extraordinary physical properties and photovoltaic performance. Among these, inorganic perovskite quantum dots (QDs) stand out for their prominent merits, such as quantum confinement effects, high photoluminescence quantum yield, and defect-tolerant structures. Additionally, ligand engineering and an all-inorganic composition lead to a robust platform for ambient-stable QD devices. This review presents the state-of-the-art research progress on inorganic perovskite QDs, emphasizing their electronic applications. In detail, the physical properties of inorganic perovskite QDs will be introduced first, followed by a discussion of synthesis methods and growth control. Afterwards, the emerging applications of inorganic perovskite QDs in electronics, including transistors and memories, will be presented. Finally, this review will provide an outlook on potential strategies for advancing inorganic perovskite QD technologies.

Synthesis, Structure, and Characterization of 4,4'-(Anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) Bismuth Iodide (C30H22N2)3Bi4I18, an Air, Water, and Thermally Stable 0D Hybrid Perovskite with High Photoluminescence Efficiency

4,4'-(Anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) bismuth iodide (C₃₀H₂₂N₂)₃Bi₄I₁₈ (AEPyBiI) was obtained as a black powder by a very simple route by mixing an acetone solution of BiI₃ and an aqueous solution of C₃₀H₂₂N₂I₂. This novel perovskite is air and water stable and displays a remarkable thermal stability up to nearly 300 °C. The highly conjugated cation C₃₀H₂₂N₂ ²⁺ is hydrolytically stable, being nitrogen atoms quaternarized, and this accounts for the insensitivity of the perovskite toward water and atmospheric oxygen under ambient conditions. The cation in aqueous solution is highly fluorescent under UV irradiation (emitting yellow-orange light). AEPyBiI as well is intensely luminescent, its photoluminescence emission being more than 1 order of magnitude greater than that of high-quality InP epilayers. The crystal structure of AEPyBiI was determined using synchrotron radiation single-crystal X-ray diffraction. AEPyBiI was extensively characterized using a wide range of techniques, such as X-ray powder diffraction, diffuse reflectance UV-vis spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopies, thermogravimetry-differential thermal analysis (TG-DTA), elemental analysis, electrospray ionization mass spectroscopy (ESI-MS), and photoluminescence spectroscopy. AEPyBiI displays a zero-dimensional (0D) perovskite structure in which the inorganic part is constituted by binuclear units consisting of two face-sharing BiI₆ octahedra (Bi₂I₉ ^3- units). The C₃₀H₂₂N₂ ²⁺ cations are stacked along the a-axis direction in a complex motif. Considering its noteworthy light-emitting properties coupled with an easy synthesis and environmental stability, and its composition that does not contain toxic lead or easily oxidable Sn(II), AEPyBiI is a promising candidate for environmentally friendly light-emitting devices.

In Situ Tetraalkylammonium Ligand Engineering of Organic-Inorganic Hybrid Perovskite Nanoparticles for Enhancing Long-Term Stability and Optical Tunability

Organic-inorganic hybrid perovskite nanoparticles (OIHP NPs) have attracted scientific attention owing to their efficient photoluminescence with optical tunability, which is highly advantageous for optoelectronic applications. However, the limited long-term stability of OIHP NPs has significantly hindered their practical application. Despite several synthetic strategies and encapsulation methods to stabilize OIHP NPs, complicated multi-step procedures are often required. In this study, we introduce an in situ ligand engineering method for stabilizing and controlling the optical properties of OIHP NPs using tetraalkylammonium (TAA) halides with various molecular structures at different concentrations. Our one-pot ligand engineering substantially enhanced the stability of the OIHP NPs without post-synthetic processes. Moreover, in certain cases, approximately 90% of the initial photoluminescence (PL) intensity was preserved even after a month under ambient conditions (room temperature, 20-50% relative humidity). To determine the role of ligand engineering in stabilizing the OIHP NPs, the surface binding properties of the TAA ligands were thoroughly analyzed using Raman spectroscopy. Specifically, the permanent positive charge of the TAA cations and consequent effective electrostatic interactions with the surfaces of the OIHP NPs are pivotal for preserving the initial PL intensity. Our investigation is beneficial for developing OIHP nanomaterials with improved stability and controlled photoluminescence for various optoelectronic applications, such as light-emitting devices, photosensitizers, photodetectors, photocatalysis, and solar cells.

Low-Dimensional Metal-Halide Perovskites as High-Performance Materials for Memory Applications

Metal-halide perovskites have drawn profuse attention during the past decade, owing to their excellent electrical and optical properties, facile synthesis, efficient energy conversion, and so on. Meanwhile, the development of information storage technologies and digital communications has fueled the demand for novel semiconductor materials. Low-dimensional perovskites have offered a new force to propel the developments of the memory field due to the excellent physical and electrical properties associated with the reduced dimensionality. In this review, the mechanisms, properties, as well as stability and performance of low-dimensional perovskite memories, involving both molecular-level perovskites and structure-level nanostructures, are comprehensively reviewed. The property-performance correlation is discussed in-depth, aiming to present effective strategies for designing memory devices based on this new class of high-performance materials. Finally, the existing challenges and future opportunities are presented.

A Review of Performance Prediction Based on Machine Learning in Materials Science

With increasing demand in many areas, materials are constantly evolving. However, they still have numerous practical constraints. The rational design and discovery of new materials can create a huge technological and social impact. However, such rational design and discovery require a holistic, multi-stage design process, including the design of the material composition, material structure, material properties as well as process design and engineering. Such a complex exploration using traditional scientific methods is not only blind but also a huge waste of time and resources. Machine learning (ML), which is used across data to find correlations in material properties and understand the chemical properties of materials, is being considered a new way to explore the materials field. This paper reviews some of the major recent advances and applications of ML in the field of properties prediction of materials and discusses the key challenges and opportunities in this cross-cutting area.

Reversible Phase Segregation and Amorphization of Mixed-Halide Perovskite Nanocrystals in Glass Matrices

Mixed-halide perovskites have attracted great attention in applications of lighting and photovoltaic devices due to their excellent properties. Understanding the phase segregation mechanism of mixed-halide perovskite has significance for suppressing the performance degradation of optoelectronic devices. Herein, we investigate the mixed-halide perovskite nanocrystals (NCs) in isolation from the external factors (oxygen, moisture, and pressure) using glass encapsulation, which shows excellent photostability against phase segregation. By monitoring the structural evolution of the NCs in glass matrices, the coexisting phase segregation and amorphization of mixed-halide perovskites are observed in real-time. The results show that thermal-induced local temperature increase plays a dominant role in the phase segregation of mixed-halide perovskite NCs. The recovery process is driven by the spontaneous crystallization of the amorphous mixed-halide phase. The clarified dynamic equilibrium process between the compositional segregation (mixing) and structural disorder (order) gives us a better insight into the reversible phase segregation mechanism of mixed-halide perovskite.

Unraveling the Effect of Halogen Ion Substitution on the Noise of Perovskite Single-Crystal Photodetectors

Halide mixing in perovskites has been an efficient way to engineer the bandgap, stability, and charge carrier mobility of lead halide perovskites, while its effect on the noise of lead halide perovskite photodetectors is still unknown. We present the preparation of mixed halide methylammonium lead perovskite single crystals by the solution temperature-decreasing method. Planar-structured photodetectors were constructed on the basis of these mixed halide perovskite single crystals. The effect of halogen ion substitution on the noise of devices was investigated by analyzing their dark current spectra. It is shown that the single-crystal photodetectors with higher levels of chloride suffer from larger noise thus have lower detectivity. Density functional theory calculations have also been proposed to reveal the effect of halogens on band structure. These results provide a comprehensive understanding of mixed halide perovskites and may help in the design and preparation of higher-performance devices.

Light-Controlled Reconfigurable Optical Synapse Based on Carbon Nanotubes/2D Perovskite Heterostructure for Image Recognition

Two-dimensional (2D) halide perovskite material is characterized by a mixed conducting behavior that possesses both electronic and ionic conductivity. The study on the influence of the light on ion migration in the 2D perovskite is helpful to improve the performance of perovskite-based optoelectronic devices. Here, we constructed an exfoliated 2D perovskite/carbon nanotubes (CNTs) heterostructure optical synapse, in which CNTs can be used as nanoprobes to qualitatively observe the ion aggregation or dissipation process in 2D perovskite, and found that light significantly changes the memory curve of the reconfigurable optical synapses. Through the molecular dynamic simulation, the dynamic process of ion migration in the heterostructure was simulated and the electrostatic interaction effect of nonequilibrium charge distribution of CNTs on iodide ion was demonstrated. Finally, an effective light-controlled process was realized through the synapses, which in situ regulated the performance of the weight-value discretized BP (WD-BP) neural network. This work lays a foundation for the future development of intelligent nano-optoelectronic devices.

Förster Resonance Energy Transfer Assisted Enhancement in Optoelectronic Properties of Metal Halide Perovskite Nanocrystals

Regulated excited state energy and charge transfer play a pivotal role in nanoscale semiconductor device performance for efficient energy harvesting and optoelectronic applications. Herein, we report the influence of Förster resonance energy transfer (FRET) on the excited-state dynamics and charge transport properties of metal halide perovskite nanocrystals (PNCs), CsPbBr₃, and its anion-exchanged counterpart CsPbCl₃ with CdSe/ZnS quantum dots (QDs). We report a drop in the FRET efficiency from ∼85% (CsPbBr₃) to ∼5% (CsPbCl₃) with QDs, inviting significant alteration in their charge transport properties. Using two-probe measurements we report substantial enhancement in the current for the blend structure of PNCs with QDs, originating from the reduced trap sites, compared to that of the pristine PNCs. The FRET-based upshot in the conduction mechanism with features of negative differential resistance and negligible hysteresis for CsPbBr₃ PNCs can add new directions to high performance-based photovoltaics and optoelectronics.