Optoelectronic Information Research Articles

Sub-bandgap charge harvesting and energy up-conversion in metal halide perovskites: ab initio quantum dynamics

Metal halide perovskites (MHPs) exhibit unusual properties and complex dynamics. By combining ab initio time-dependent density functional theory, nonadiabatic molecular dynamics and machine learning, we advance quantum dynamics simulation to nanosecond timescale and demonstrate that large fluctuations of MHP defect energy levels extend light absorption to longer wavelengths and enable trapped charges to escape into bands. This allows low energy photons to contribute to photocurrent through energy up-conversion. Deep defect levels can become shallow transiently and vice versa, altering the traditional defect classification into shallow and deep. While defect levels fluctuate more in MHPs than traditional semiconductors, some levels, e.g., Pb interstitials, remain far from band edges, acting as charge recombination centers. Still, many defects deemed detrimental based on static structures, are in fact benign and can contribute to energy up-conversion. The extended light harvesting and energy up-conversion provide strategies for design of novel solar, optoelectronic, and quantum information devices.

Integrated electro-optic modulator on a lead zirconate titanate-silicon nitride heterogeneous platform.

Integrated electro-optic (EO) modulators are the core components of the optoelectronic information technology, and lithium niobate is currently the most widely used crystalline thin film material; however, finite EO coefficients limit the modulation efficiency of the modulators. In this Letter, we present an integrated EO modulator using a microring resonator on the lead zirconate titanate (PZT) and silicon nitride (SiN) heterogeneous platform. The microwave attenuation is reduced by using low loss tangent and dielectric constant SiN as the electrode substrate, achieving an EO bandwidth of 33 GHz. Thanks to the high quality of the PZT film deposition and the substantial EO overlap of our structure, ultrahigh modulation efficiency with the half-wave voltage-length product of 0.7 V·cm is achieved. In addition, as a remarkable result, an 80-Gbps on-off keying signal is generated using the modulator.

Spatially Resolved Light-Induced Ferroelectric Polarization in α-In2Se3/Te Heterojunctions.

Light-induced ferroelectric polarization in 2D layered ferroelectric materials holds promise in photodetectors with multilevel current and reconfigurable capabilities. However, translating this potential into practical applications for high-density optoelectronic information storage remains challenging. In this work, an α-In2Se3/Te heterojunction design that demonstrates spatially resolved, multilevel, nonvolatile photoresponsivity is presented. Using photocurrent mapping, the spatially localized light-induced poling state (LIPS) is visualized in the junction region. This localized ferroelectric polarization induced by illumination enables the heterojunction to exhibit enhanced photoresponsivity. Unlike previous reports that observe multilevel polarization enhancement in electrical resistance, the device shows nonvolatile photoresponsivity enhancement under illumination. After polarization saturation, the photocurrent increases up to 1000 times, from 10-12 to 10-9 A under the irradiation of a 520nm laser with a power of 1.69 nW, compared to the initial state in a self-driven mode. The photodetector exhibits high detectivity of 4.6×1010 Jones, with a rise time of 27 µs and a fall time of 28 µs. Furthermore, the device's localized poling characteristics and multilevel photoresponse enable spatially multiplexed optical information storage. These results advance the understanding of LIPS in 2D ferroelectric materials, paving the way for optoelectronic information storage technologies.

Dimension-Controlled VO2 Film for Optoelectronic Logic Gates and Information Encryption.

As the fields of photonics and information technology develop, a lot of novel applications based on VO2 material, such as optoelectronic computing and information encryption, have been developed. While the performance of these devices was not only closely associated with the VO2 phase transition properties but also depended on their dimensional characteristics. In the current study, we conducted the dimension-controlled vanadium dioxide (VO2) film growth, resulting in the epitaxial 2-dimensional (2D) VO2 film and well-distributed 3-dimensional (3D) VO2 crystal film deposition, respectively. It was revealed that, unlike the 2D film, the pronounced localized surface plasmon resonance dominated the near-infrared spectrum across the phase transition for the 3D VO2 film due to the naturally formed meta-surface structure, which showed a transmittance valley in the infrared spectrum after metallization. Based on this distinct infrared spectrum feature in the 3D VO2 film, we proposed an optoelectronic logic gate controlled by the input voltage and the probing Vis/IR light. By detecting the transmittance states of the probing light with different wavelengths, we achieved multistate encoding functions and demonstrated the information encryption application. This new conception device also showed great potential for some other applications such as optoelectronic coupled computing, information encryption, and optical near-field sensing computing.

Efficient chiral hydrogel template based on supramolecular self-assembly driven by chiral carbon dots for circularly polarized luminescence

Since the chiral emission of excited states is observed on carbon dots (CDs), exploration towards the design and synthesis of chiral CDs nanomaterials with circularly polarized luminescence (CPL) properties has been at a brisk pace. In this regard, the “host and guest” co-assembly strategy based on the combination of CDs and chiral templates has been of unique interest recently for its convenient operation, multicolor tunable CPL, and wide application of prepared CDs-composited materials in optoelectronic devices and information encryption. However, the existing chiral templates that match perfectly with chiral CDs exhibiting optical activity both in ground and excited states are rather scarce. In this work, we synthesize the chiral CDs that could induce the spontaneous supramolecular self-assembly of N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to form chiral hydrogels with helical nanostructure. The co-assembled hydrogels show powerful chiral template function, which not only enable chiral CDs with a luminescence dissymmetry factor (glum) up to 10-2, but also have universal chiral transfer to inserted dye molecules, realizing full-color CPL and Förster resonance energy transfer (FRET) CPL as well as the distinction between left and right circularly polarized light. This CPL-active template based on chiral CDs enriches the design scenario of chiral functionalized nanomaterials.

UV–Vis photodetector based on electrospun MgFe2O4 microfibers

Photodetector is an essential component in the effort to develop optoelectronic information system. Magnesium ferrite (MgFe2O4) with a band gap around 1.9 eV is expected to serve as a good photosensitive semiconductor for UV–Vis photodetectors. Here, the first MgFe2O4 microfibers based photodetector was demonstrated by combining the unique one-dimensional morphology of microfibers and the photoelectric conversion performance of MgFe2O4 semiconductor. The uniform MgFe2O4 microfibers were prepared by electrospinning method and then transferred to the FTO (fluorine-doped tin oxide) conductive substrate to obtain the simple photodetector. The device exhibited nearly linear response to 360 nm UV light with a maximum responsivity of 63.1 μA/W. It also showed a significant response to 450 nm blue light. Our findings not only provide a feasible path for constructing MgFe2O4 based photodetector but also open up a brand new application field of MgFe2O4 semiconductor.

Best practices in measuring absorption at the macro- and microscale

The fraction of light absorbed in a material is a key parameter for a wide range of optoelectronic and energy devices, including solar cells, light emitting diodes, and photo(electro)chemical devices. It can reveal detailed performance information and establish a material’s theoretical efficiency limits. However, measuring absorption accurately is challenging, especially due to scattering effects at the macroscale and achieving perpendicular illumination over a small area at the microscale. In this tutorial, we present concepts and best practices in measuring absorption at both the macro- and micro-scale. We also give examples of using absorption to reveal critical optoelectronic information in energy devices. This work aims at standardizing the recording of absorption measurements across a number of fields, allowing for improved microscale understanding of a wide range of samples.

Synergetic Responses of Multiple Functions Induced by Phase Transition in Molecular Materials.

Materials that integrate magnetism, electricity and luminescence can not only improve the operational efficiency of devices, but also potentially generate new functions through their coupling. Therefore, multifunctional synergistic effects have broad application prospects in fields such as optoelectronic devices, information storage and processing, and quantum computing. However, in the research field of molecular materials, there are few reports on the synergistic multifunctional properties. The main reason is that there is insufficient awareness of how to obtain such material. In this brief review, we summarized the molecular materials with this characteristic. The structural phase transition of substances will cause changes in their physical properties, as the electronic configurations of the active unit in different structural phases are different. Therefore, we will classify and describe the multifunctional synergistic complexes based on the structural factors that cause the first-order phase transition of the complexes. This enables us to quickly screen complexes with synergistic responses to these properties through structural phase transitions, providing ideas for studying the synergistic response of physical properties in molecular materials.

Achieving Efficient Dark Blue Room‐Temperature Phosphorescence with Ultra‐Wide Range Tunable‐Lifetime

AbstractTunable‐lifetime room‐temperature phosphorescence (RTP) materials have been widely studied due to their broad applications. However, only few reports have achieved wide‐range lifetime modulation. In this work, ultra‐wide range tunable‐lifetime efficient dark blue RTP materials were realized by doping methyl benzoate derivatives into polyvinyl alcohol (PVA) matrix. The phosphorescence lifetimes of the doped films can be increased from 32.8 ms to 1925.8 ms. Such wide range of phosphorescence lifetime modulation is extremely rare in current reports. Moreover, the phosphorescence emission of the methyl 4‐hydroxybenzoate‐doped film is located in the dark blue region and the phosphorescence quantum yield reaches as high as 15.4 %, which broadens their applications in organic optoelectronic information. Further studies demonstrated that the reason for the tunable lifetime was that the magnitude of the electron‐donating ability of the substituent group modulates the HOMO–LUMO and singlet‐triplet energy gap of methyl benzoate derivatives, as well as the ability to non‐covalent interactions with PVA. Moreover, the potential applications of luminescent displays and optical anti‐counterfeiting of these high‐performance dark blue RTP materials have been conducted.

Low-Power Perovskite Neuromorphic Synapse with Enhanced Photon Efficiency for Directional Motion Perception.

The advancement of artificial intelligent vision systems heavily relies on the development of fast and accurate optical imaging detection, identification, and tracking. Framed by restricted response speeds and low computational efficiency, traditional optoelectronic information devices are facing challenges in real-time optical imaging tasks and their ability to efficiently process complex visual data. To address the limitations of current optoelectronic information devices, this study introduces a novel photomemristor utilizing halide perovskite thin films. The fabrication process involves adjusting the iodide proportion to enhance the quality of the halide perovskite films and minimize the dark current. The photomemristor exhibits a high external quantum efficiency of over 85%, which leads to a low energy consumption of 0.6 nJ. The spike timing-dependent plasticity characteristics of the device are leveraged to construct a spiking neural network and achieve a 99.1% accuracy rate of directional perception for moving objects. The notable results offer a promising hardware solution for efficient optoneuromorphic and edge computing applications.

Achieving Efficient Dark Blue Room-Temperature Phosphorescence with Ultra-Wide Range Tunable-Lifetime.

Tunable-lifetime room-temperature phosphorescence (RTP) materials have been widely studied due to their broad applications. However, only few reports have achieved wide-range lifetime modulation. In this work, ultra-wide range tunable-lifetime efficient dark blue RTP materials were realized by doping methyl benzoate derivatives into polyvinyl alcohol (PVA) matrix. The phosphorescence lifetimes of the doped films can be increased from 32.8 ms to 1925.8 ms. Such wide range of phosphorescence lifetime modulation is extremely rare in current reports. Moreover, the phosphorescence emission of the methyl 4-hydroxybenzoate-doped film is located in the dark blue region and the phosphorescence quantum yield reaches as high as 15.4 %, which broadens their applications in organic optoelectronic information. Further studies demonstrated that the reason for the tunable lifetime was that the magnitude of the electron-donating ability of the substituent group modulates the HOMO-LUMO and singlet-triplet energy gap of methyl benzoate derivatives, as well as the ability to non-covalent interactions with PVA. Moreover, the potential applications of luminescent displays and optical anti-counterfeiting of these high-performance dark blue RTP materials have been conducted.

Design and Application of Intelligent Transportation Systems Based on Optoelectronic Information Processing and Time-optimal Algorithms

The project employs photoelectric information acquisition technology and integrates it with an intersection waiting time optimization algorithm to achieve traffic light control at urban intersections through photoelectric acquisition, data analysis, data processing, and module control. Its objective is to efficiently and effectively address the issue of traffic congestion at intersections, providing a solution for the development of intelligent urban transportation.

Functionalization of Violet Phosphorus Quantum Dots with Azo-Containing Star-Shape Polymer for Optically Controllable Memory

Quantum dots (QDs) are emerging as promising candidates for innovative memristive materials, owing to their distinct surface, quantum size, and edge effects. Recent research has focused on tailoring QDs with specific organic molecules to fine-tune charge transfer states between the host and grafted species, as well as enhancing their dispersibility and processability. Violet phosphorus (VP), a newly discovered two-dimensional phosphorus allotrope, offers excellent carrier dynamics, predictable modifiability, and superior oxidation resistance, making it a promising contender in this domain. In this study, we synthesized a rich azobenzene-containing star-shaped polymer diazonium salt (AzoSPD) to functionalize violet phosphorus quantum dots (VPQDs), with the dual objectives of enhancing organic dispersibility and introducing photo-switching capabilities. The synthesized AzoSPD–VPQDs exhibit intramolecular charge transfer characteristics under electrical stimuli of ambient conditions, displaying significant non-volatile rewriteable memory properties and a substantial switching ratio exceeding 2 × 103. Furthermore, the high resistance state (HRS) current can be enhanced by nearly 40 times under 465 nm illumination, enabling optoelectronic information sensing and storage within a single device. This work not only provides insights into enhancing the optoelectronic properties of QDs through functional organic molecular modification but also represents a pioneering exploration of the potential applications of VPQDs in novel memristors.

A Universal Strategy for Modular Tunable Full‐Color Circularly Polarized Luminescent Materials with Afterglow

AbstractCircularly polarized luminescence (CPL) has shown significant potential for use in optoelectronic information and biomedical applications. Previously, the construction of CPL in thin films has often required the introduction of chiral groups into the system, which is efficient but complicated to synthesize and separate enantiomeric isomers. This manuscript proposes a simple and efficient strategy to construct dye‐doped polyvinyl alcohol (PVA) thin films with controlled orientation of the panchromatic CPL signal. This strategy can be generalized to the construction of thin‐film CPL. Besides, the metal‐free pure circularly polarized afterglow material is reported here to be adjustable. Moreover, the PVA films can be cut and stacked in a modular way to obtain different emission effects to induce mixed CPL, and three primary colors can be piled up together to induce white CPL. The PVA film has good prospects for use in optical devices, for example, anti‐counterfeiting of information and optical information encryption.

Amplification and Dynamic Control of Circularly Polarized Luminescence in Poly (vinyl Alcohol)/CdSe@CdS Nanorod Assembly Twisted‐Stacking Hetero‐Structures

AbstractChiroptical materials with strong and switchable circularly polarized luminescence (CPL) properties have gained considerable interest due to their feasible applications in optoelectronic devices, sensing, and information encryption. However, in most cases, their luminescence dissymmetry factor (glum) and figure of merit (FOM) values remain very low. Herein, a novel heterogeneous twisted‐stacking structure is proposed, which endows with strong CPL amplification (a maximum of ≈15‐fold enhancement) over traditional homogeneous structures and a high FOM value up to 0.11. Interestingly, their CPL performance (including the sign, magnitude, and spectral position) and the FOM values can be precisely manipulated or even inversed by simply uniaxial stretching, since the phase retardation of the anisotropic poly (vinyl alcohol) layer can be controlled. Moreover, by combining with the viologen gel electrochromic system, the in situ voltage‐driven switching and patterning of the CPL signal can be successfully achieved, with low operation voltage and good cycling stability. This study provides a creative strategy for fabricating strong and electrical switchable CPL‐active materials, which promise new opportunities in miniaturized smart electrochiroptical devices for future information technology.

Intrinsic vacancy in 2D defective semiconductor In2S3 for artificial photonic nociceptor

It is crucial to develop an advanced artificially intelligent optoelectronic information system that accurately simulates photonic nociceptors like the activation process of a human visual nociceptive pathway. Visible light reaches the retina for human visual perception, but its excessive exposure can damage nearby tissues. However, there are relatively few reports on visible light–triggered nociceptors. Here, we introduce a two-dimensional natural defective III–VI semiconductor β-In2S3 and utilize its broad spectral response, including visible light brought by intrinsic defects, for visible light–triggered artificial photonic nociceptors. The response mode of the device, under visible light excitation, is very similar to that of the human eye. It perfectly reproduces the pain perception characteristics of the human visual system, such as ‘threshold,’ ‘relaxation,’ ‘no adaptation’, and ‘sensitization’. Its working principle is attributed to the mechanism of charge trapping associated with the intrinsic vacancies in In2S3 nanosheets. This work provides an attractive material system (intrinsic defective semiconductors) for broadband artificial photonic nociceptors.

Optical switch of electron-hole and electron-electron collisions in semiconductors

Optoelectronic information devices are being developed to achieve an ultrafast speed, an ultrasmall size, and an ultralow power consumption. Here, the authors demonstrate the precise switch of two light wave driven carrier dynamic processes in semiconductors by using a weak control laser. One is the electron-hole collision recombination leading to high-order harmonic generation. The other is the electron-electron impact excitation leading to stimulated simulation. This all-optical switch has an ultrafast speed, a low threshold, and a broad spectral responsiveness.

Axial InN/InGaN Nanorod Array Heterojunction Photodetector with Ultrafast Speed (Adv. Electron. Mater. 3/2023)

Photodetectors In article number 2201193, Wenliang Wang, Guoqiang Li, and co-workers present high-performance photodetectors based on an axial InN/InGaN nanorod arrays heterojunction. The unique chargetransport pathways along the axial heterojunction and the band alignment of the heterojunction significantly improve the response speed of the photodetector. The devices hold great potential in optoelectronic information technology.

Chiro-Optoelectronic Encodable Multilevel Thin Film Electronic Elements with Active Bio-Organic Electrolyte Layer.

It is suggested that chiral photonic bio-enabled integrated thin-film electronic elements can pave the base for next-generation optoelectronic processing, including quantum coding for encryption as well as integrated multi-level logic circuits. Despite recent advances, thin-film electronics for encryption applications with large-scale reconfigurable and multi-valued logic systems are not reported to date. Herein, highly secure optoelectronic encryption logic elements are demonstrated by facilitating the humidity-sensitive helicoidal organization of chiral nematic phases of cellulose nanocrystals (CNCs) as an active electrolyte layer combined with printed organic semiconducting channels. The ionic-strength controlled tunable photonic band gap facilitates distinguishable and quantized 13-bit electric signals triggered by repetitive changes of humidity, voltage, and the polarization state of the incident light. As a proof-of-concept, the integrated circuits responding to circularly polarized light and humidity are demonstrated as unique physically unclonable functional devices with high-level logic rarely achieved. The convergence between functional nanomaterials and the multi-valued logic thin-film electronic elements can provide optoelectronic counterfeiting, imaging, and information processing with multilevel logic nodes.

Recent Developments of Electrically Pumped Nanolasers

AbstractElectrically pumped nanolasers have achieved many exciting achievements and display a wide range of potential application prospects in the fields of optoelectronic chips, information storage, and biosensing. However, there is lacking an in‐depth and extensive review of the recent development of electrically pumped nanolasers. Herein, a detailed and comprehensive overview of the electrically pumped nanolasers is first given according to the device configurations, including electrically pumped single nanolaser, nanoarray lasers, nanobeam lasers, and plasmonic nanolasers with different cavity structures. Furthermore, some problems and challenges restricting the development of electrically pumped nanolasers are summarized, and the corresponding solutions and development directions are proposed. This review will provide valuable suggestions for optimizing the device structure of electrically pumped nanolasers with new high‐gain semiconductor materials and particularly further promote their rapid application development.