Search Results (215)

Intermediate band solar cells require in-gap electronic states that remain sufficiently extended to sustain collective electronic coupling and facilitate carrier motion. We investigate how structural disorder affects an intermediate band formed by coupled colloidal quantum dots embedded in a perovskite-like matrix. The system is represented by a single-orbital tight-binding Hamiltonian on a dilated face-centered-cubic lattice containing 4000 quantum dots, with system sizes between 1372 and 5324 in the finite-size analysis. Radius dispersion modifies on-site energies and hopping amplitudes, whereas positional disorder acts mainly through variations in interdot separation. Eigenstate extension is quantified using the normalized participation ratio. To distinguish spectral broadening from the loss of useful extended states, we also evaluate the mean participation of a contiguous threshold-defined spectral core, its relative energy width, and their product as a combined robustness descriptor. For the adopted baseline parameter set, degradation is energy selective: states near the spectral edges lose participation before states near the band center. At equal nominal amplitudes, radius disorder produces a stronger response than positional disorder, although the two amplitudes do not represent equal realized variances. A positional-disorder amplitude of 0.05 retains approximately 86% of the ordered-reference value of the combined descriptor, whereas a radius-disorder amplitude of 0.05 reduces it to about 22%; when both amplitudes are 0.05, about 14% remains. The model displays a comparatively robust regime near ${\sigma }_R=0.02$, a model-dependent crossover around ${\sigma }_R=0.03$–$0.04$, and strong degradation at larger values. Finite-size results are consistent with near-extensive scaling of the effective core participation number over the simulated sizes, but do not establish a thermodynamic mobility edge. These findings identify quantum-dot size uniformity as the more restrictive model control variable for preserving an extended intermediate-band core. Full article

Visible light communication (VLC) has emerged as a transformative optical wireless technology for sixth-generation (6G) networks, offering license-free spectrum access, inherent electromagnetic-interference immunity, high spatial confinement, and the unique ability to combine high-speed wireless connectivity with solid-state lighting infrastructure. However, the transition from conventional VLC links to practical 6G optical wireless systems requires far more than advanced modulation and signal processing. Future VLC performance will be strongly determined by the co-design of photonic front-ends, including high-speed transmitters, spectrally engineered emitters, reconfigurable optical interfaces, intelligent receivers, and energy-autonomous detection units. This article provides a comprehensive, device-centered review of photonic hardware and artificial intelligence (AI) enablers for next-generation 6G VLC systems. Particular attention is given to micro-LEDs, laser diodes, color-conversion materials, including perovskite quantum dots, advanced photodetectors, imaging receivers, wavelength-shifting fiber receivers, solar-cell-based receivers, optical reconfigurable intelligent surfaces (RISs), metasurfaces, beam-steering components, and optical wireless power transfer. This review discusses how AI can support inverse photonic design, transmitter and receiver calibration, nonlinear impairment mitigation, channel-aware beam control, and energy-aware resource management. Unlike broader VLC surveys that mainly emphasize network architecture, this article provides a device-centered perspective on AI-enabled photonic integration for 6G VLC, supported by a comprehensive survey of recent experimental demonstrations. Key challenges related to bandwidth, optical efficiency, receiver field of view, mobility, safety, standardization, and practical deployment are summarized, followed by a research roadmap for 2025–2032. Full article

Group III-nitride semiconductors (GaN, AlN, InN) serve as foundational materials for modern optoelectronics, high-frequency microelectronics, and next-generation energy harvesting devices. However, traditional high-temperature epitaxy (>700 °C) introduces severe thermal stress, high dislocation densities, and fundamental incompatibility with flexible substrates or CMOS back-end-of-line (BEOL) processes. Plasma-enhanced atomic layer deposition (PEALD) provides a disruptive, ultra-low thermal budget (<300 °C) pathway for atomic-scale precision growth and conformal coating. This review systematically summarizes recent frontiers in PEALD-synthesized Group III-nitrides and 2D/3D polar heterostructures. First, we dissect the microscopic nucleation kinetics, surface bond reconstruction, and impurity suppression mechanisms across diverse substrates, including Si, sapphire, quartz, metals, and flexible polymers. Next, we highlight 2D template-assisted van der Waals epitaxy on graphene and MoS2, and elucidate polarization-driven dipole interactions and band alignment engineering at 2D/3D polar interfaces (e.g., α-In₂Se₃, Janus MoSSe). Furthermore, we comprehensively discuss innovative applications in advanced photovoltaics (as electron transport and passivation layers in perovskite and quantum dot-sensitized solar cells), silicon-based microcavity lasers, high-electron-mobility transistors (HEMTs), and flexible multimodal sensors. Finally, key technological challenges—including the low-thermal-budget paradox, wafer-scale uniformity, and deposition throughput—are addressed alongside future perspectives in area-selective ALD and neuromorphic computing, presenting a cohesive blueprint from underlying physics to macroscopic system integration. Full article

Perovskite solar cells (PSCs) have reached certified efficiencies exceeding 26%, yet the gap to the Shockley–Queisser limit and insufficient operational stability remain key obstacles to commercialization. Quantum dots (QDs) offer a versatile platform to address both challenges through their size-tunable bandgaps, high photoluminescence yields, and solution processability. This review systematically examines four QD integration strategies in PSCs: transport layer modification, active layer doping, UV conversion layers, and tandem sub-cells. The underlying mechanisms—including defect passivation, energy-level engineering, crystallization control, and ion migration suppression—are critically compared across these approaches. Despite significant advances, challenges persist, including the ligand–charge transport trade-off, the environmental toxicity of Pb/Cd-containing QDs, poor reproducibility, and the absence of standardized stability testing protocols. By providing a mechanism-oriented assessment across all device components, this review offers a clear framework for selecting appropriate QD strategies and identifies priority research directions. The perspective of QD strategies in this review provides a useful and significant reference for approaching the theoretical PCE limits of single-junction PSCs by reducing non-radiative recombination and improving light utilization, while QD-based tandem architectures offer a viable route toward surpassing the single-junction Shockley–Queisser limit. Full article

Third-generation photovoltaic (PV) technologies, such as dye-sensitized solar cells (DSSCs), organic solar cells (OSCs), quantum-dot solar cells (QDSSCs), and perovskite solar cells (PSCs), are characterized by properties that enable applications beyond conventional silicon-based devices. However, despite remarkable progress in third-generation solar cells, significant challenges related to efficiency, stability, scalability, and commercialization remain significant. The purpose of this review work was to summarize recent developments in third-generation photovoltaic technologies, including component materials design, configurations, performance data, limitations, and future research directions. The reported studies demonstrated crucial improvements in power conversion efficiency, which exceeded 15% for DSSC, 20% for OSC, 12% for QDSSC, and 26% for PSC. The key challenges to commercialization include further improvements in efficiency, better stability, and meeting the environmental requirements. Although important technological and environmental challenges remain, third-generation solar cells are expected to contribute to future sustainable energy systems due to their high efficiency potential, low-cost fabrication, and possible incorporation of environmentally friendly materials in the structure of the cells. The photovoltaic performance under indoor conditions and the aspect of a sustainable approach were identified as recent research trends. Full article

This work reports the colloidal synthesis of Nd-containing mixed-halide perovskite quantum dots described as CsPb(Nd)Br_3−γCl_γ, followed by post-synthetic surface modification with an acid-activated amino-functional siloxane. This notation is used deliberately because the available FE-SEM, DLS, EDX, and optical data confirm the formation of an Nd-containing mixed-halide colloidal perovskite system, but do not provide direct crystallographic proof of substitutional Nd³⁺ incorporation at the Pb²⁺ B-site. The obtained dispersions show stable blue emission with a maximum at about 458 nm, a photoluminescence quantum yield of about 56%, an essentially invariant emission maximum when the excitation wavelength is varied from 300 to 390 nm, and monoexponential decay kinetics with a characteristic lifetime of 6.67 ± 0.97 ns. Field-emission scanning electron microscopy combined with morphometric analysis of at least 150 particles indicates a nanoscale size distribution with an average equivalent diameter of 8.8 nm, a median of 7.3 nm, and 93.25% of particles smaller than 25 nm. Dynamic light scattering confirms a narrow hydrodynamic size distribution in the 7–9 nm range and a low polydispersity index. Elemental mapping by EDX confirms the co-presence of Cs, Pb, Br, Cl, and Nd in the analyzed particles. The observed blue shift is discussed in terms of the combined effect of chloride incorporation, nanoscale size, possible Nd-related perturbation of the local electronic/defect structure, and reduced non-radiative losses after surface passivation. No definitive crystallographic assignment of Nd to a specific lattice site is claimed; the composition is therefore treated as nominal, and the structural interpretation remains provisional pending XRD/XPS or related studies. Full article

This review evaluates the role of advanced materials in optimizing the efficiency, sustainability, and market integration of solar photovoltaic (PV) technologies. Our work bridges insights from both mature (crystalline silicon (c-Si)) and novel perovskites (PSs), organic photovoltaics (OPVs), and quantum dot solar cell (QDSC) materials, thereby providing a unified view of the present and the future of PV research. We highlight the key breakthroughs for the different material classes, describing their unique features, record performance, and contribution to lowering the cost of solar energy. In particular, while some progress has been made, we recognize that challenges such as the stability of the device under varying environmental conditions, the environmental impact of the materials, and the scalability of the manufacturing processes are still there. In conclusion, we give an overview of the research topics that can pave the way for the future. We support the formation of hybrid structures, the finding of lead-free alternatives, multi-junction architectures, and integrated solutions that not only help to overcome the current limitations but also facilitate the global energy transition. Full article

All-inorganic lead halide perovskite quantum dots (QDs), featuring high photoluminescence quantum yield, narrow full width at half maximum, and solution processability, show great promise for high-color-purity displays and optoelectronic devices. Their emission peak position and stability are highly dependent on the surface coordination environment, and achieving controllable color tuning while maintaining stability without altering the primary synthetic route remains a critical challenge. Herein, we propose a facile solution-phase post-treatment strategy using TMCS, which can react with the oleate ligands on the CsPbBr₃ QD surface while providing abundant Cl⁻ ions, thereby leading to partial halide exchange, achieving continuous tuning of the emission wavelength from 499 nm to 473 nm. The appearance of new absorption peaks in the FTIR spectra indicated the successful introduction of TMCS and the in situ generation of HCl, which led to surface etching and passivation. After being heated at 40 °C for 6 h, the TMCS-50 sample retained 39% of its initial photoluminescence intensity, while the pristine CsPbBr₃ QD sample retained only 8%, demonstrating that TMCS treatment significantly improves the thermal stability of the CsPbBr₃ QDs. Full article

Photodetectors have undergone widespread, gradual application. Correlation detectors with varying properties are used in diverse fields. This review systematically summarizes the principles, properties, and applications of various photoelectric detectors reported in the past five years, compares their similarities and differences, and further discusses their respective advantages and disadvantages, applicable scenarios, and development prospects. The review covers self-powered detectors, which are very convenient and widely used in consumer electronics and portable wearable devices, and discusses the structural design and photoelectric performance of devices based on P–N junctions, perovskites, silicon–polymer hybrid composites, graphene, hybrid graphene/PbS quantum dot systems, and other novel material architectures. Compound photoelectric detectors enable multifunctional integration and intellectualization. At the same time, their high sensitivity and broad-spectrum response can expand the detection wavelength range to cover the ultraviolet, visible, and infrared bands and enhance the detection of weak optical signals. Finally, this review summarizes current challenges, including cumbersome fabrication processes, susceptibility of detection stability to environmental interference, and limited functionality, and focuses on recent advances in various photodetectors, where breakthroughs are expected. Full article

The discovery of quantum dots (QDs) earned a Nobel Prize and has led to widespread applications in research and technology. In this review, we focus on the use of QDs in solid-state solar cells (QDSCs). We begin with an overview of the basic principles of SCs. Then, we discuss how device architecture has developed over recent decades, setting the stage for the final section on fourth-generation solar cells (Perspective section). We also highlight progress in material development, starting with lead- and cadmium-based QDs and progressing to more recent carbon- and perovskite-based QDs. Additionally, we review materials used for electron-transport layers (ETLs) and hole-transport layers (HTLs). The articles also present recent advances in QDSCs across various QD types. In the final section, we recommend that future research focus on three main areas: QD active-layer materials, material interfaces, and device architecture. These efforts could lead to sustainable QDSCs that potentially surpass the Shockley–Queisser (SQ) limit. Full article

Microlasers are innovative photonics devices that have recently attracted attention for their unique characteristics, including compactness, broad spectral emission, and low lasing threshold. These properties are beneficial in biophotonics as these lasers can interact with biological materials without causing damage, especially for optical biosensing applications. Among the optical materials recently used as gain media in microlasers are organic dyes, rare-earth ions, fluorescent proteins, and semiconductors, including quantum dots and perovskites. Moreover, different optical cavities and current laser configurations have increased the versatility of microlasers. Recently, digital sensing methods based on novel algorithms, machine learning, and neural networks have been combined with microlaser systems to enhance their accuracy and expand their applications. This work provides a comprehensive review of recent progress in microlasers, covering gain media, microcavity types, and their applications in biophotonics, including conventional spectral-based sensing and new digital approaches for the biomedical field. Full article

CsPbBr₃ perovskite quantum dots (QDs) have attracted significant attention for optoelectronic applications owing to their outstanding optical properties, yet achieving controlled synthesis with high stability under mild conditions remains a challenge. The room-temperature synthesis of CsPbBr₃ perovskite quantum dots using a coprecipitation method is systematically investigated in this work, with an emphasis on how the structural and optical properties of the QDs are influenced by the Br/Pb ratio and OA/OAm ratio. The findings show that controlling the Br/Pb and OA/OAm ratios can effectively influence the size, crystalline phase, and surface passivation properties of CsPbBr₃ quantum dots. The photoluminescence peak shifts blue and the bandgap widens when the Br/Pb ratio rises due to a decrease in quantum dot size. This is mainly explained by more effective surface covering by Br⁻ ions and increased quantum confinement effects. The resultant quantum dots demonstrate ideal optical performance at a Br/Pb ratio of 75 and an OA/OAm ratio of 1.5, with dense ligand coverage, superior defect passivation, and markedly improved stability under UV irradiation and in aqueous environments. Variations in the Br/Pb and OA/OAm ratios affect the binding configuration and coverage of ligands on the quantum dot surface, thereby influencing the relationship between non-radiative recombination and the quantum confinement effect. The LED fabricated with the as-synthesized high-performance quantum dots demonstrates a wide color gamut, covering 129.45% of the NTSC standard, indicating strong potential for display applications. Full article

Perovskite quantum dots (PQDs) face significant performance limitations due to surface defects, which are not sufficiently addressed by conventional single-passivation methods. We introduce a dual-passivation strategy that synergistically combines bifunctional ligand 3-(N,N-dimethyloctadecylammonium)-propanesulfonate (SB3-18) treatment with silica coating to simultaneously passivate undercoordinated Pb²⁺ ions and bromine vacancies in red-emitting CsPb(Br/I)₃ PQDs. This approach nearly triples the photoluminescence quantum yield (PLQY, from 23% to 58%). Systematic structural, morphlogical, binding energy, Fermi level and optical analyses confirm effective defect suppression and enhanced exciton luminescence. The dual-passivated sample QDs:SB3-18@SiO₂ also exhibit excellent environmental stability, retaining 85% of their initial emission after 30 min in air and exhibiting improved UV resistance. By combining the PQDs with a CGSO:Tb³⁺ mechanoluminescent phosphor, a composite film is fabricated with bimodal optical response—color-selective photoluminescence under UV excitation and stress-activated green emission upon scratching. This work presents a robust route to high-performance PQDs and demonstrates their potential for advanced anticounterfeiting and smart optical applications. Full article

Perovskite quantum dots (PeQDs) are highly promising luminescent materials for next-generation displays owing to their excellent optoelectronic properties, such as narrow emission linewidth, high photoluminescence quantum yield, tunable bandgap, and solution processability. Blue-emitting PeQDs are particularly crucial for realizing full-color displays with high color purity. This review systematically summarizes synthesis strategies for blue-emitting PeQDs and their recent advances in perovskite light-emitting diodes (PeLEDs). We first introduce the working principles of PeLEDs and detail three primary approaches to achieving blue emission through mixed-halide engineering, quasi-two-dimensional structure construction via A-site cation substitution, and quantum size effect utilization. We then review mainstream synthesis methods, including hot-injection, ligand-assisted reprecipitation, and post-synthetic anion exchange, discussing their respective advantages and limitations. Key device optimization strategies are also outlined, covering surface passivation, core–shell structures, interface engineering, and light outcoupling enhancement. Finally, we address current challenges in material stability, efficiency roll-off, and charge imbalance and provide an overview of future research directions for high-performance blue PeLEDs based on PeQDs. Full article

In this study, a gold nanocage composite perovskite quantum dot fluorescent probe (MB-GNCs-PQDs) was designed and constructed. The GNCs-PQDs composite system was formed by the combination of gold nanocages (GNCs) and perovskite quantum dots (PQDs). Spectral analysis confirmed that its fluorescence intensity was significantly enhanced by 15.38% compared with that of pure PQDs. Furthermore, amino modification was performed on the nanomaterial. Through the specific design of molecular beacons (MB), the fluorescence emission spectrum of the probe was matched with the absorption peak of the quencher group BHQ2, and the effective closure of the fluorescence signal was achieved based on the Fluorescence Resonance Energy Transfer (FRET) effect. Subsequently, MB was immobilized on the surface of the composite system via amino covalent conjugation to complete the probe preparation. The prepared probe was applied to the detection of miRNA-4529-3P and miR-301b-3p, which are tumor markers of non-small cell lung cancer (NSCLC). The hybridization of target molecules with MB could trigger the disruption of FRET and the recovery of fluorescence signal, exhibiting excellent recognition performance. This study provides an experimental basis for the preparation of composite fluorescent probes, and the developed probe has potential application value in the field of tumor marker detection. Full article