- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Investigation on formation process of metal atomic filament for metal sulfide atomic switch by electrical measurement
摘要： We have studied the formation process of the metal atomic filament for the metal sulfide atomic switches by the electrical measurement. The switching between ON and OFF states of the atomic switch is controlled by the application of the bias voltage for the atomic switches. The SET (OFF→ON) and RESET (ON→OFF) voltages were investigated for the atomic switch where the Ag2S or Cu2S layer was sandwiched between the Pt and Ag or Cu electrodes. The SET and RESET voltages of the Ag/Cu2S/Pt and Cu/Ag2S/Pt were close to those of the Ag/Ag2S/Pt atomic switch, and different from those of the Cu/Cu2S/Pt atomic switch. These results indicated that the dominant chemical species of the making and breaking part of the metal filament were Ag, and that the source of the metal filament was both the sulfide layer and the metal electrode.
关键词： Atom switch,I-V measurement,Ion migration
更新于2025-09-23 15:23:52
-
Nanoscale spatial mapping of charge carrier dynamics in perovskite solar cells
摘要： Charge carrier dynamics and behaviors are key parameters and need to be mapped at the nanoscale in order to search for correct materials for high-performance solar cells. Unfortunately, currently, there are no existing tools or capabilities that can simultaneously map charge carrier dynamics at nanometer range in solar cells. Here we use a Transient Photo-response AFM (TP-AFM) to map for the first time apparent carrier recombination lifetime (τr), transport time (τt) and diffusion length (LD) in hybrid perovskites solar cells. These spatially resolved parameters reveal substantial variations at grain boundaries (GBs) τr, τt and LD at GBs broaden the performance of these state-of-the-art mixed cation perovskites. Detail analysis of these parameters allow us to conclude that reduced density of trap states and recombination in mixed cation perovskites at GBs and its surrounding locations (extending to several nanometers into the grain interior) implies less ion migration. This first of its kind experimental realization of nanoscale mapping of charge carrier dynamics in photovoltaic materials can be used for applications in other optoelectronic devices.
关键词： Perovskites,Nanoscale mapping and ion migration,Grain boundary,Charge carrier dynamics
更新于2025-09-23 15:21:01
-
Role of PCBM in the Suppression of Hysteresis in Perovskite Solar Cells
摘要： The power conversion efficiency of inorganic–organic hybrid lead halide perovskite solar cells (PSCs) is approaching that of those made from single crystalline silicon; however, they still experience problems such as hysteresis and photo/electrical-field-induced degradation. Evidences consistently show that ionic migration is critical for these detrimental behaviors, but direct in-situ studies are still lacking to elucidate the respective kinetics. Three different PSCs incorporating phenyl-C61-butyric acid methyl ester (PCBM) and a polymerized form (PPCBM) is fabricated to clarify the function of fullerenes towards ionic migration in perovskites: 1) single perovskite layer, 2) perovskite/PCBM bilayer, 3) perovskite/PPCBM bilayer, where the fullerene molecules are covalently linked to a polymer backbone impeding fullerene inter-diffusion. By employing wide-field photoluminescence imaging microscopy, the migration of iodine ions/vacancies under an external electrical field is studied. The polymerized PPCBM layer barely suppresses ionic migration, whereas PCBM readily does. Temperature-dependent chronoamperometric measurements demonstrate the reduction of activation energy with the aid of PCBM and X-ray photoemission spectroscopy (XPS) measurements show that PCBM molecules are viable to diffuse into the perovskite layer and passivate iodine related defects. This passivation significantly reduces iodine ions/vacancies, leading to a reduction of built-in field modulation and interfacial barriers.
关键词： perovskites,ion migration,J–V curve hysteresis,PCBM
更新于2025-09-23 15:21:01
-
Polymer Controlled Growth and Wrapping of Perovskite Single Crystals Leading to Better Device Stability and Performance
摘要： Commodity scale polymer is used for controlling the nucleation and growth of single crystals of organolead halide perovskite. The polymer (polystyrene (PS)) cross-links and strongly interact with PbI2 and MAI (MAPbI3 perovskite precursors) resulting in the control of the crystallization process. The PS concentration modulates the nucleation time, crystal size and the number of perovskite single crystals. In addition, the PS based MAPbI3 crystals show an enhanced performance as well as improved thermal and environmental stability. Specifically, the PS-MAPbI3 crystals show 3 times higher photocurrent than plain MAPbI3 crystals and maintains a stable structure for more than 50 days (1200 h) under continuous 0.1 sun illumination in the air with a relative humidity of 40–45%. The improved performance and stability are attributed to the direct interaction between the PS and perovskite, which greatly reduces the ion migration, defect traps and charge recombination, and improves the carrier mobility and lifetime.
关键词： ion migration effect,photocurrent,perovskite,long-term stability,optoelectronics,crystal growth
更新于2025-09-23 15:21:01
-
Light-Enhanced Ion Migration in Two-Dimensional Perovskite Single Crystals Revealed in Carbon Nanotubes/Two-Dimensional Perovskite Heterostructure and Its Photomemory Application
摘要： Two-dimensional (2D) hybrid perovskite sandwiched between two long-chain organic layers is an emerging class of low-cost semiconductor materials with unique optical properties and improved moisture stability. Unlike conventional semiconductors, ion migration in perovskite is a unique phenomenon possibly responsible for long carrier lifetime, current?voltage hysteresis, and low-frequency giant dielectric response. While there are many studies of ion migration in bulk hybrid perovskite, not much is known for its 2D counterparts, especially for ion migration induced by light excitation. Here, we construct an exfoliated 2D perovskite/carbon nanotube (CNT) heterostructure field effect transistor (FET), not only to demonstrate its potential in photomemory applications, but also to study the light induced ion migration mechanisms. We show that the FET I?V characteristic curve can be regulated by light and shows two opposite trends under different CNT oxygen doping conditions. Our temperature-dependent study indicates that the change in the I?V curve is probably caused by ion redistribution in the 2D hybrid perovskite. The first principle calculation shows the reduction of the migration barrier of I vacancy under light excitation. The device simulation shows that the increase of 2D hybrid perovskite dielectric constant (enabled by the increased ion migration) can change the I?V curve in the trends observed experimentally. Finally, the so synthesized FET shows the multilevel photomemory function. Our work shows that not only we could understand the unique ion migration behavior in 2D hybrid perovskite, it might also be used for many future memory function related applications not realizable in traditional semiconductors.
关键词： photomemory,carbon nanotube,ion migration,Two-dimensional perovskite,heterostructure
更新于2025-09-23 15:19:57
-
Role of the La/K Compositional Ratio in the Properties of Waveguides Written by Fs-Laser Induced Element Redistribution in Phosphate-Based Glasses
摘要： The local modification of the composition of glasses by high repetition femtosecond laser irradiation is an attractive method for producing photonic devices. Recently, the successful production of waveguides with a refractive index contrast (?n) above 10?2 by fs-laser writing has been demonstrated in phosphate glasses containing La2O3 and K2O modifiers. This large index contrast has been related to a local enrichment in lanthanum in the light guiding region accompanied by a depletion in potassium. In this work, we have studied the influence of the initial glass composition on the performance of waveguides that are produced by fs-laser induced element redistribution (FLIER) in phosphate-based samples with different La and K concentrations. We have analyzed the contribution to the electronic polarizability of the different glass constituents based on refractive index measurements of the untreated samples, and used it to estimate the expected index contrast caused by the experimentally measured local compositional changes in laser written guiding structures. These estimated values have been compared to experimental ones that are derived from near field images of the guided modes with an excellent agreement. Therefore, we have developed a method to estimate before-hand the expected index contrast in fs-laser written waveguides via FLIER for a given glass composition. The obtained results stress the importance of considering the contribution to the polarizability of all the moving species when computing the expected refractive index changes that are caused by FLIER processes.
关键词： photonic devices,waveguides,element redistribution,ion migration,fs-laser writing,refractive index contrast,glass
更新于2025-09-23 15:19:57
-
The diverse passivation effects of fullerene derivative on hysteresis behavior for normal and inverted perovskite solar cells
摘要： [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is usually used to passivate the trap states and ion defects for suppressing hysteresis in both normal and inverted perovskite solar cells. Here, we find that the normal cell with the perovskite film fabricated on the PCBM film shows an evident hysteresis, while the inverted cell with the perovskite film covered by the PCBM film shows nearly no hysteresis, and the PCBM-Perovskite interface impacts on the hysteresis vastly. The poor PCBM surface wettability results in an inefficient carrier extraction at the interface and a red-shift of photoluminescence emission for the perovskite film coated on the PCBM film, which results from the plentiful trap states and ion defects inside the perovskite film due to its poor crystallization. Thus, the trapping/de-trapping processes and slow ion migration eventually lead to the hysteresis. For the perovskite film covered by the PCBM film, due to the good wettability of the perovskite film, PCBM molecules easily permeate into the perovskite film to passivate the trap states and ion defects, which improves the carrier extraction and thus eliminates the hysteresis of the inverted cell.
关键词： Hysteresis behavior,Trap states,Perovskite solar cells,Ion migration,Carrier extraction,PCBM
更新于2025-09-23 15:19:57
-
Halide perovskites for resistive random-access memories
摘要： Halide perovskite based resistive random-access memory (ReRAM) devices are emerging as a new class of revolutionary data storage devices because their switching material—halide perovskite—has received considerable attention in recent years. Among the electrical characteristics of the material, its current–voltage (I–V) hysteresis, which may occur due to defect formation and migration, means that ReRAM can employ halide perovskites as a resistive switching material. Many studies have been conducted on resistive switching materials; however, the investigation of halide perovskites for ReRAM devices is still in the early research stages; therefore, the application of halide perovskites in ReRAM devices is a topic worth studying. Herein, we introduce halide perovskites and their operating mechanism within a ReRAM device. Moreover, recent notable achievements along with future challenges have been reviewed.
关键词： Halide perovskites,ion migration,hysteresis,resistive random-access memories,switching materials,ReRAM
更新于2025-09-19 17:15:36
-
Emerging Conductive Atomic Force Microscopy for Metal Halide Perovskite Materials and Solar Cells
摘要： Metal halide perovskite materials, benefiting from a combination of outstanding optoelectronic properties and low-cost solution-preparation processes, show tremendous potential for optoelectronics and photovoltaics. However, the nanoscale inhomogeneities of the electronic properties of perovskite materials cause a number of difficulties, such as recombination, stability, and hysteresis, all of which seriously restrict device performance. Scanning probe microscopy, as a high-resolution imaging technique, has been widely used to connect local properties and micro-area morphologies to overall device performance. Conductive atomic force microscopy (C-AFM) can realize a real-space visualization of topography coupled with optoelectronic properties on a microscopic scale and thereby is uniquely suited to probe the local effects of perovskite materials and devices. The fundamental principles, alternative operation modes, and development of C-AFM are comprehensively reviewed, and applications in perovskite solar cells (PSCs) for electronic transport behavior, ion migration and hysteresis, ferroelectric polarization, and facet orientation investigation are discussed. A comprehensive understanding and summary of up-to-date applications in PSCs is beneficial to further fully exploit the potential of such an emerging technique, so as to provide a novel and effective approach for perovskite materials analysis.
关键词： ferroelectricity,perovskite solar cells,conductive atomic force microscopy,ion migration,perovskite materials,electronic transport behavior
更新于2025-09-19 17:13:59
-
Frequency- and Power-Dependent Photoresponse of a Perovskite Photodetector Down to the Single-Photon Level
摘要： Organometallic halide perovskites attract strong interests for their high photoresponsivity and solar cell efficiency. However, there was no systematic study of their power and frequency dependent photoresponsivity. We identified two different power-dependent photoresponse types in methylammonium lead iodide perovskite (MAPbI3) photodetectors. In the first type, photoresponse remains constant from 5 Hz to 800 MHz. In the second type, absorption of a single photon can generate a persistent photoconductivity of 30 pA under an applied electric field of 2.5×104 V/cm. Additional absorbed photons, up to 8, linearly increase the persistent photoconductivity, which saturates with absorption of more than 10 photons. This is different than single photon avalanche detectors (SPADs) because the single photon response is persistent as long as the device is under bias, providing unique opportunities for novel electronic and photonic devices such as analog memories for neuromorphic computing. We propose an avalanche-like process for iodine ions and estimate that absorption of a single 0.38 aJ photon triggers motion of 108-9 ions, resulting in accumulations of ions and charged vacancies at the MAPbI3/electrode interfaces to cause band bending and change of material electric properties. We have made the first observation that single-digit photon absorption can alter the macroscopic electric and optoelectronic properties of a perovskite thin film.
关键词： Perovskite,photodetectors,impact ionization,ion migration,single photon sensitivity
更新于2025-09-19 17:13:59