Photoelectric Devices Research Articles

Excitonic one-photon absorption of one- and two-dimensional C60 polymers: Insights from many-body first-principles calculations

By solving the many-body Bethe–Salpeter equation, we explored the excitonic one-photon absorption of one- and two-dimensional C60 polymers. We studied seven polymeric structures including C60-chain, two structures with quasi-tetragonal phases (qTP1 and qTP2), and four structures with quasi-hexagonal phases (qHP1, ML-qHP2, BL-qHP2, and bulk-qHP2). The one-photon excitonic transitions were analyzed in detail relative to the independent particle transitions. Significant red-shifts (0.4 and 0.2 eV for ML-qHP2 and BL-qHP2, respectively) were observed in the excitonic one-photon absorption of low-dimensional polymers compared to bulk polymers. The red-shift can be related to the dimensional and interlayer dependences of screening effect which lead to different binding energies (0.61, 0.44, and 0.27 eV for ML-qHP2, BL-qHP2, and bulk-qHP2, respectively). For two qHPs (i.e., qHP1 and ML-qHP2), different connection modes between C60 molecules lead to different types (direct and indirect for qHP1 and ML-qHP2, respectively) of electronic band gap, and they also have different spectral profiles due to different hole and electron densities of excitons. Finally, the C60-chain formed by [2 + 2] cycloadditions has a direct band gap of 2.09 eV which is desirable for applications in photoelectric devices based on the solar spectrum.

Opto-electro-thermo-mechanical behaviours of perovskite plates

Metal-halide perovskites are rapidly emerging as promising candidates for next-generation solar cells and photoelectric technologies. However, their structural behaviours considering opto-electro-thermo-mechanical properties in multi-physics fields have not yet been fully understood, thus limiting their engineering applications. This paper proposes a new opto-electro-thermo-elastic model taking into account photostriction, photothermal effect, electrostriction, and piezoelectricity for lead halide perovskites and investigates their static and dynamic opto-electro-thermo-mechanical behaviours. The governing equations of perovskite plates are derived within the theoretical framework of first-order shear deformation theory and are numerically solved using the Chebyshev-Ritz method. Comprehensive parametric studies are carried out to examine the influences of multi-physics fields on the critical light intensity, critical electric field, static bending, elastic buckling, free vibration, as well as dynamic responses of perovskite plates. Numerical results show that light illumination, photoinduced temperature rise, and applied electric field play an important role in bending deformation, dynamic deflection, critical buckling load, and free vibration frequency hence need to be taken into consideration for the design of perovskite-based photoelectric devices.

Harnessing a silicon carbide nanowire photoelectric synaptic device for novel visual adaptation spiking neural networks.

Visual adaptation is essential for optimizing the image quality and sensitivity of artificial vision systems in real-world lighting conditions. However, additional modules, leading to time delays and potentially increasing power consumption, are needed for traditional artificial vision systems to implement visual adaptation. Here, an ITO/PMMA/SiC-NWs/ITO photoelectric synaptic device is developed for compact artificial vision systems with the visual adaption function. The theoretical calculation and experimental results demonstrated that the heating effect, induced by the increment light intensity, leads to the photoelectric synaptic device enabling the visual adaption function. Additionally, a visual adaptation artificial neuron (VAAN) circuit was implemented by incorporating the photoelectric synaptic device into a LIF neuron circuit. The output frequency of this VAAN circuit initially increases and then decreases with gradual light intensification, reflecting the dynamic process of visual adaptation. Furthermore, a visual adaptation spiking neural network (VASNN) was constructed to evaluate the photoelectric synaptic device based visual system for perception tasks. The results indicate that, in the task of traffic sign detection under extreme weather conditions, an accuracy of 97% was achieved (which is approximately 12% higher than that without a visual adaptation function). Our research provides a biologically plausible hardware solution for visual adaptation in neuromorphic computing.

Fabrication of highly luminescent and thermally stable composites of sulfur nanodots through surface modification and assembly.

Sulfur nanodots (S-dots) have emerged as a promising luminescent material to excel over traditional heavy metal-based quantum dots. However, their relatively low emission efficiency and poor thermal stability in the solid state have limited their wide applications in photoelectric devices. In this work, highly luminescent, with a photoluminescence quantum yield higher than 50%, and thermally stable composites of S-dots were produced through modulating their surface states and aggregation behaviors by introducing pyromellitic dianhydride (PMDA) and benzoyleneurea (BEU), respectively. PMDA eliminated the relatively short-lived surface states and defects on the surface of S-dots and BEU regulated the aggregation states and facilitated the energy transfer from BEU to S-dots. The as-obtained composites also showed significantly improved thermal stability compared to S-dots, aided by the hydrophobic chemical groups and dense matrix of PMDA and BEU, which extended their applications in fabricating light-emitting diodes. Our presented results provide a new approach to produce highly luminescent S-dots, which widen their applications in the fields of bioimaging, sensing, photoelectric devices, and environmental science.

A controllable interlayer shielding effect in twisted multilayer graphene quantum dots.

When multilayer graphene (MLG) is subjected to a vertical electric field, electrons traverse across the layers and its interlayer electrical conductance and shielding effect exhibit remarkable diversity, leading to exotic phenomena and diverse applications in photoelectric devices. The rearrangement of electrons induced by this external field is aptly described by polarizability, which quantifies the electronic response to the applied field. In this work, we have developed a polarizability decomposition scheme based on field-induced electron density variations computed using a first-principles approach. This scheme allows us to isolate the inter- and intra-layer contributions from the total polarizability of twisted multilayer graphene (TMG) quantum dots. The inter- and intra-layer counterparts reflect the charge transfer (CT) and field shielding effects among the layers, respectively. While the strongest shield effect is observed between the outermost two layers, the largest CT change is noted in the outermost layers, but small or nearly zero CT changes in the inner layers. Significant CT and shielding effects are observed not only in strongly coupled Bernal stacking, but also in the structures misaligned from full-(AA)N stacking by a small and size-dependent twist angle. The dielectric behaviors of the TMG quantum dots of a few layers are layer-dependent and different from those of typical dielectrics. Moreover, both the shielding and CT effects exhibit variation with thickness, twist angle and disc size, suggesting controllable conductive/dielectric conversion in the vertical direction. Considering the inter- and intralayer polarizability, our study addresses the precise modulation of interlayer conductance and shielding effect for TMG quantum dots, essential for microstructure design and performance manipulation of MLG-based photoelectric devices.

Achiral substituent- and stoichiometry-controlled inversion of supramolecular chirality and circularly polarized luminescence in ternary co-assemblies.

Handedness inversion of supramolecular chirality and circularly polarized luminescence (CPL) in assembled systems containing more than two components with higher complexity is of prominent importance to simulate biological multicomponent species and design advanced chiral materials, but it remains a considerable challenge. Herein, we have successfully developed ternary co-assembly systems based on aromatic amino acids, vinylnaphthalene derivatives and 1,2,4,5-tetracyanobenzene with effective chirality transfer. Notably, the handedness of supramolecular chirality and CPL can be readily inverted by changing the residues of amino acids, the substituents of achiral vinylnaphthalene derivatives, or by adjusting the stoichiometric ratio. The hydrogen bonds, charge transfer interactions, and steric hindrance are proved to be the crucial factors for the chirality inversion. This flexible control over chirality not only offers insights into developing multicomponent chiral materials with desirable handedness from simple molecular building blocks, but also is of practical value for use in chiroptics, chiral sensing, and photoelectric devices.

P3HT:ITIC polymer based photovoltaic biointerfaces for neural photostimulation

Aims/Purpose: Optoelectronic neural interfaces have diverse applications in comprehending neural network and treatment of neurodegenerative conditions especially in the field of the vision impairments. We aimed to use the non‐invasive, capacitive photocurrent generation stimulated by near‐infrared light in the biological environment integrating P3HT:ITIC devices to provide neuroprotective and neurodegenerative effects with reducing axonal damage through local repetitive photo‐stimulation.Methods: In this study, we performed neuron stimulation with the help of ITO/ZnO/P3HT:ITIC photoactive polymer implant placed on an indium tin oxide (ITO) glass. To evaluate the biocompatibility of the P3HT:ITIC devices, CTG cell viability and LDH leak assay were performed on primary nervous and visual system cells including Mio‐M1 and primary astrocytes. Cell specific biomarkers were examined by immunofluorescence staining to demonstrate short‐ and long‐term morphological changes and neural network improvements on both the biointerface and ITO control substrates.Results: We fabricated NIR‐responsive photovoltaic P3HT:ITIC biointerface with ZnO nanoparticles (NPs) as electron transport layer and P3HT:ITIC thin films as photoactive layer on ITO glass substrates. After evaluation of their stability, we showed that primary neurons, astrocytes and Müller glia cells on the biointerface have high cell viability, low cytotoxicity and preserved cellular network and morphology after 2 weeks of culture condition.Conclusions: Our study will provide novel solutions to existing problems in electrostimulation devices by exploring capabilities of wirelessly functional, biocompatible organic polymer‐based photoelectric devices with low cost of production. They have a potential in establishing a platform for the development of near infrared light‐controlled electrostimulation treatment, that can improve axonal healing in retina and optic nerve injuries.

Photoelectric Synaptic Device Based on Bilayerd OR/OP-InGaZnO for Neuromorphic Computing

Photoelectric Synaptic Device Based on Bilayerd O_R/O_P-InGaZnO for Neuromorphic Computing

A novel functionalized ferrocene derivative as a hole transport material for efficient perovskite solar cells: insight into the ultrafast interfacial carrier dynamics and charge transport

Recently, lead halide perovskites have been developing rapidly in the field of photo-electric functional devices.

Calibration method of relative spectral response function of indirect imaging spectrometer

In imaging spectrometers, area array detectors are usually used as photoelectric conversion devices, but the inconsistency of the spectral response among pixels can distort the collected target spectra. To improve the spectral radiometric accuracy of imaging spectrometers, calibrating and correcting the inconsistency of the spectral response among pixels is essential. The signal received by each pixel of area array detector of the indirect imaging spectrometer is usually the superposition of the target multi-spectral radiation signals or full-spectral radiation signals. Therefore, its relative spectral radiometric calibration requires measuring the spectral response of each pixel at different wavelengths on the array detector. Under the ideal conditions, the response values of each pixel in the area array detector are different, so the indirect imaging spectrometer cannot simply calibrate the relative spectral response (RSR) function between pixels by using the method of “monochromator + integrating sphere”. In this work, taking the interferometric imaging spectrometer for example, we analyze the influence of the inconsistency of the RSR among pixels on the target spectral radiation measurement accuracy, and propose a system-level RSR function measurement method for the indirect imaging spectrometer based on the Fourier transform modulation calibration source. In addition, we establish a mathematical model for calibrating the RSR function,and provide guidelines for selecting calibration system parameters such as light source, spectral resolution, and OPD sampling interval. The simulation results show that under the ideal noise-free condition, the 1% spectral response inconsistency among pixels results in a relative error of 1.02% to the recovered spectra. After RSR correction, the relative error of the recovered spectra of different rows decreases to 0.08%. Furthermore, in this work we simulate and analyse the influence of spectral signal-to-noise ratio on the calibration accuracy of the RSR function, and point out that increasing the brightness of the calibration light source, extending exposure time, and combining multi-frame interferograms can enhance RSR function calibration accuracy in practical applications. The research result can provide a theoretical basis for realizing the relative spectral radiometric calibration of indirect imaging spectrometer, which is of great significance in promoting quantitative spectral remote sensing.

An adjustable multistage resistance switching behavior of a photoelectric artificial synaptic device with a ferroelectric diode effect for neuromorphic computing.

Neuromorphic computing, which mimics biological neural networks, is widely regarded as the optimal solution for addressing the limitations of traditional von Neumann computing architecture. In this work, an adjustable multistage resistance switching ferroelectric Bi2FeCrO6 diode artificial synaptic device was fabricated using a sol-gel method with a simple process. The device exhibits nonlinearity in its electrical characteristics, demonstrating tunable multistage resistance switching behavior and a strong ferroelectric diode effect through the manipulation of ferroelectric polarization. One of its salient advantages resides in its capacity to dynamically regulate its polarization state in response to an external electric field, thereby facilitating the fine-tuning of synaptic connection strength while maintaining synaptic stability. The device is capable of accurately simulating the fundamental properties of biological synapses, including long/short-term plasticity, paired-pulse facilitation, and spike-timing-dependent plasticity. Additionally, the device exhibits a distinctive photoelectric response and is capable of inducing synaptic plasticity by light signal activation. The utilization of a femtosecond laser for the scrutiny of carrier transport mechanisms imparts profound insights into the intricate dynamics governing the optical memory effect. Furthermore, utilizing a convolutional neural network (CNN) architecture, the recognition accuracy of the MNIST and fashion MNIST datasets was improved to 95.6% and 78%, respectively, through the implementation of improved random adaptive algorithms. These findings present a new opportunity for utilizing Bi2FeCrO6 materials in the development of artificial synapses for neuromorphic computation.

Nanocrystals as performance-boosting materials for solar cells.

Nanocrystals (NCs) have been widely studied owing to their distinctive properties and promising application in new-generation photoelectric devices. In photovoltaic devices, semiconductor NCs can act as efficient light harvesters for high-performance solar cells. Besides light absorption, NCs have shown great significance as functional layers for charge (hole and electron) transport and interface modification to improve the power conversion efficiency and stability of solar cells. NC-based functional layers can boost hole/electron transport ability, adjust energy level alignment between a light absorbing layer and charge transport layer, broaden the absorption range of an active layer, enhance intrinsic stability, and reduce fabrication cost. In this review, recent advances in NCs as a hole transport layer, electron transport layer, and interfacial layer are discussed. Additionally, NC additives to improve the performance of solar cells are demonstrated. Finally, a summary and future prospects of NC-based functional materials in solar cells are presented, addressing their limitations and suggesting potential solutions.

First-principles study on the optoelectronic and photocatalytic properties of the C2h-Janus Al2XY(X/Y[dbnd]S, Se and Te) monolayers

Recently, two-dimensional (2D) new C2h phase of group III monochalcogenides have exhibited great potentials for applications in the field of photoelectric devices because of their outstanding optoelectronic properties. Here, we theoretically predict the C2h phase of aluminum monochalcogenide (C2h-Al2XY) (X/YS, Se and Te; X≠Y) compounds with Janus structure via first-principles calculations. Janus C2h-Al2XY monolayers are found to be thermodynamically, dynamically, energetically, and mechanically stable. The entire Janus C2h-Al2XY monolayers exhibit semiconducting properties, with a band gap ranging from 2.25 to 2.57 eV, as calculated using the HSE06 method. The obvious anisotropic mechanical and optical characteristics are observed. All Janus C2h-Al2XY monolayers present high optical absorption in the ultraviolet and visible regions, suggesting that these monolayers have a favorable efficiency for absorbing solar light. These significant results imply that Janus C2h-Al2XY monolayers can be used in the fields such as nano-electronics and optoelectronics. Specifically, it has been found that the band edge position of Janus C2h-Al2SSe is capable of meeting the redox potential requirements for photocatalytic water splitting. Furthermore, biaxial strain can significantly adjust the band gap of the C2h-Al2SSe and enhance its visible light absorption. Most importantly, within the biaxial strain range of −6%–6 %, the band edge positions of Janus C2h-Al2SSe consistently satisfy the redox potentials required for photocatalytic water splitting. These findings indicate that the Janus C2h-Al2SSe monolayer is promising for photocatalytic water splitting due to its moderate band gap and suitable band edge positions as well as good absorption in the visible region.

A changeable critical state for a switchable photocurrent direction via the photo-electrochemical photocurrent polarity switching effect in BiFeO3 nanoparticulate films.

The photoelectrochemical photocurrent switching (PEPS) effect to change the photocurrent direction from cathodic to anodic via external bias is an important phenomenon. Specifically, tuning the critical state or the potential corresponding to a switchable photocurrent direction through easily controllable parameters is crucial for developing efficient photo-electrocatalyst systems. Although the PEPS effect has been reported in quite a few recently published studies, the changeable critical state has not yet been demonstrated. In this study, for the first time, we present a photoelectrochemical (PEC) system based on bismuth ferrite (BiFeO3) nanoparticulate films that demonstrates a changeable critical state controlled via the composition of an electrolyte medium. In particular, the ionic strength (tuned via addition of inert salt) and the concentration of dissolved oxygen in an electrolyte medium are noted to dictate the potential corresponding to the critical state. Importantly, we demonstrate that this potential can be predicted using the Nernst equation by considering electrolyte energy level rearrangement and the kinetic theory of semiconductor electrodes. This study enhances the understanding of carrier transport in PEC activities and enables precise control over the reversal of the photocurrent direction that may pave the way for developing sophisticated multifunctional photoelectric devices and efficient photo-electrocatalyst systems.

Enhanced photoelectric performance of Bi2O2Se/CuInP2S6 heterojunction via ferroelectric polarization in two-dimensional CuInP2S6.

Two-dimensional (2D) materials have drawn tremendous interest as promising materials for photoelectric devices due to their extraordinary properties. As an outstanding 2D photoelectric material, Bi2O2Se (BOS) has exhibited good performance and great potential in photoelectric applications. In this report, we have constructed a photoelectric heterojunction based on BOS and CuInP2S6 (CIPS) nanosheets to achieve enhanced photoelectric performance. With modulation of the ferroelectric-polarization-induced built-in electric field in CIPS, the photogenerated carriers in BOS are effectively separated to form a stable current that is independent of the applied voltage, so that the photoelectric performance of the heterojunction is significantly improved. The photoresponsivity (R), external quantum efficiency (EQE), and normalized detectivity (D*) are calculated and analyzed to evaluate the photodetection performance of the heterojunction. Results demonstrate excellent photoelectric performance of BOS/CIPS heterojunction under irradiation of light from ultraviolet (365 nm), visible (405/550/650 nm) to near-infrared (980 nm). R, EQE, and D* are up to 338.94 A W-1, 7.65 × 104%, and 3.99 × 1010 Jones, respectively, under the condition of 550 nm and 0.24 W m-2. Meanwhile, the measured rise and fall times of the heterojunction reach 2.74 and 4.82 ms, respectively, indicating its fast photoelectric response. This work provides an effective approach to enhance the photoelectric response and stability of BOS via the ferroelectric-polarization-induced built-in electric field of CIPS.

Simulation of proton-induced primary displacement damage in GaAs under different ambient temperatures

The performance of on-orbit GaAs-based solar cells is susceptible to the displacement damage effect. The proton-induced primary displacement damage in GaAs on a geosynchronous equatorial orbit (GEO) was simulated and analyzed by combining the Monte Carlo (MC) and molecular dynamics (MD) methods. The MC simulation provided the distribution of primary knock-on atoms (PKAs) in GaAs induced by GEO-related protons to the MD simulation. In MD simulations, the effects of radiation fluence and ambient temperature on the displacement damage were considered. The simulation results showed that GEO-related protons generated a significant number of PKAs within an energy range of below 10 keV in GaAs. The high-fluence radiation emulated by the binary PKA could generate more point defects and cluster defects in GaAs than the low-fluence radiation emulated by single PKAs. As compared to room temperature (300 K), both a low (100 K) and high (500 K) ambient temperature could deteriorate the displacement damage. In addition, a high ambient temperature of 500 K could induce widespread thermal spikes in GaAs as compared to 100 and 300 K. This work can provide useful insight into the proton-induced displacement damage in GaAs and the radiation hardening of GaAs-based photoelectric devices in space.

Facile and effective synthesis strategy for terbium-doped hydroxyapatite toward photoelectric devices and flexible functional fibers

Facile and effective synthesis strategy for terbium-doped hydroxyapatite toward photoelectric devices and flexible functional fibers

Retracted: Organic Photoelectric Materials and Organic Photoelectric Devices Based on Smart Image Sensors

Retracted: Organic Photoelectric Materials and Organic Photoelectric Devices Based on Smart Image Sensors

High-performance broadband Si/ZnO heterojunction photodetector based on pyro-phototronic effect

ZnO-based photodetectors are of great significance to military early warning and medical health. However, it is challenging to detect weak signals in a broad spectral range due to the nature of wide band gap and high background carriers, seriously limiting further practical application. In this work, large-area of uniform C-axis oriented ZnO films were grown on Si substrates via sputtering technique, and Si/ZnO heterojunction photodetectors were fabricated. Because of the compact ZnO thin films structure, built-in electrical field and the enhanced pyro-phototronic coupling effect at the heterojunction interface, the fabricated Si/ZnO photodetectors exhibited excellent broadband photoresponse behaviors in the vast range from the ultraviolet to the near-infrared (355–1550 nm) under zero external bias. Especially, the device shows a significant enhancement ability to ultralow laser power (∼500 nW/cm2) with a high responsivity value of 550.6 mA/W and the great optical detectivity of 7.7 × 1012 cm Hz1/2 W−1, which is ∼1–2 orders of magnitude larger than others. These results supply an innovative strategy to develop high-performance ZnO-based photoelectric devices for weak light signal detection.

High performance photodetector based on CdS/CdS0.42Se0.58 nanobelts heterojunction

The ternary alloy CdS x Se1−x combines the physical properties of CdS and CdSe, and its band gap can be adjusted by changing the element composition. The alloy has charming photoelectric properties as well as potential application value in photoelectric devices. In this work, the CdS/CdS0.42Se0.58 nanobelt (NB) heterojunction device was prepared by chemical vapor deposition combined with a typical dry transfer technique. The heterojunction photodetector shows high light switching ratio of 6.79 × 104, large spectral responsivity of 1260 A W−1, high external quantum efficiency of 2.66 × 105% and large detectivity of 7.19 × 1015cm Hz1/2 W−1 under 590 nm illumination and 3 V bias. Its rise and decay time is about 45/90 μs. The performance of the heterojunction photodetector was comparable or even better than that of other CdS(Se) based photodetector device. The results indicate that the CdS/CdS0.42Se0.58 NB heterojunction possesses a promising potential application in high performance photodetectors.