ACS Photonics最新文献

Deep-blue perovskite quantum dot (QD) emitters with narrow emission line widths are critical for next-generation wide-color-gamut QD displays. However, achieving narrow primary deep-blue emission perovskite QDs compliant with Rec. 2100 remains challenging. This difficulty mainly arises from the intrinsic phase segregation of mixed-halide perovskite QDs, the presence of defects, and the inhomogeneous distribution of halide ions among the particles. Herein, we develop a ligand-mediated strategy for the phase separation inhibition and surface reconstruction of CsPb(Br_xCl_1–x)₃ QDs. Specifically, we implement a sequential ligand treatment protocol comprising ion exchange with methyltrioctylammonium chloride, surface cleaning using octylphosphonic acid, and defect passivation via CF₃–PEABr. This approach effectively promotes a distinct intergrain isolation and facilitates the homogenized halide distribution throughout the QDs ensemble. The resulting deep-blue quantum dot light-emitting diode (QLED) exhibits stable electroluminescence emission with an ultranarrow full width at half-maximum (fwhm) of 13.4 nm. This achievement marks the narrowest fwhm record of primary deep-blue perovskite QLEDs to date, featuring a 99.1% gamut coverage of Rec. 2100 standard. This work proposes a feasible strategy for ultrahigh color purity deep-blue QLEDs tailored for Rec. 2100 wide-color-gamut displays.

We introduce a novel method for generating a high-quality, sharply defined, nondiffracting optical bottle beam by focusing a Bessel beam propagating through a flat multilevel diffractive lens (MDL). This study highlights the impact of the MDL illuminated by a Bessel beam with suppressed sidelobes generated from a binary axicon. The resulting Bessel bottle beam exhibits a series of low- or zero-intensity zones interleaved with high-intensity regions, with periods ranging from 0.2 to 1.36 mm along the beam propagation direction. The transverse intensity profiles of these regions remain shape-invariant over long distances in free space, and thereby, the nondiffracting range of the micron-sized optical bottle beam exceeds 5 cm. We also observe that the far-field output from the MDL, when illuminated by a Bessel beam, offers advantages over that of conventional focusing lenses. Furthermore, this technique can operate on ultrafast time scales (from pico- to femtoseconds) due to the high damage thresholds of the binary axicon and MDL, enabling the generation of high-power optical bottle beams. Ultimately, our experimental approach paves the way for various applications, including high-resolution biological imaging in turbid media, particle manipulation, micromachining, and harmonic generation, by leveraging the spatial landscape of the optical bottle beam.

Understanding how organelle dynamics vary across different cell types is essential for dissecting cellular heterogeneity, yet current spectral imaging methods cannot simultaneously resolve multiple organelles in mixed populations. Here we present spectral spatial encoded microscopy (S²eM), a fluorescence imaging strategy that embeds cell identity into unique combinations of fluorescent proteins and organelle markers, enabling simultaneous multi-cell-type classification and multiplexed organelle imaging within a single field of view. Using S²eM, we distinguished four barcoded cell types and concurrently tracked the ER, mitochondrial, lysosomal, and lipid-droplet dynamics at high temporal resolution. This approach revealed cell-type-specific differences in osmotic stress responses and recovery kinetics, and uncovered ORP8-dependent alterations in LD–lysosome–mitochondria contact-site dynamics. Because all cell types are imaged under identical conditions, S²eM provides internally controlled comparisons that minimize experimental variability. These results establish S²eM as a broadly applicable platform for probing organelle behavior and interorganelle communication across heterogeneous cell populations.

Exceptional points (EPs), singularities in the spectrum of a non-Hermitian linear Hamiltonian, were predicted and claimed to enhance sensing. However, several theoretical works demonstrated that EPs do not, in general, enhance sensing when the effects of noise are taken into account. Here we introduce a sensing strategy that, like EP sensing, exploits a spectral singularity. However, the singularity we exploit is not in the energy spectrum. It is in the spectrum of fluctuations around a fixed point, which corresponds to the eigenvalues of the system’s Jacobian. Our approach, which we call Jacobian exceptional point (JEP) sensing, has practical and performance advantages over those of EP sensors. While EP sensing in linear systems usually requires two or more modes, JEP sensing can be implemented using a single nonlinear mode. Furthermore, fluctuations are essential for JEP sensing. We analyze the performance of our JEP sensor embodied in a laser-driven single-mode Kerr resonator under the influence of quantum, thermal, and external noise. We find that the square-root scaling of the signal with perturbation can be clearly detected in the presence of all three noise sources. The sensing precision is even enhanced by an optimum amount of thermal noise, but it is ultimately limited by external noise interfering with the incoming cavity field. Our work sets the theoretical foundation for implementing JEP sensing in photonics, where many of the applications targeted by EP sensing can be addressed.

The migration of iodide ions and the inefficient interfacial charge transport continue to pose significant challenges to power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In this study, we innovatively introduce a multifunctional passivation method that involves doping the P-type material 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) into the fullerene derivative (6,6)-Phenyl C₇₁-butyric acid methyl ester (PC₇₁BM). The introduction of F4TCNQ not only enhances the ability of PC₇₁BM to passivate uncoordinated Pb²⁺ ions but also promotes a uniform distribution of the passivation layer. Results indicate that this passivation layer effectively immobilizes iodide ions, preventing their random movement within the PVK films and reducing iodine-related defects. Additionally, by raising the Fermi level and enhancing the P-type characteristics, it improves hole extraction and transport, thereby reducing nonradiative recombination in the target device. Consequently, the n-i-p PSCs with the mixed passivation layer achieved a champion PCE of 25.87%, with a higher open-circuit voltage (1.182 V) and a remarkable fill factor (84.64%). Notably, in large-scale manufacturing, n-i-p mini-modules reached a commendable PCE of 22.34%. Furthermore, these devices demonstrated superior stability, maintaining over 95% of their initial efficiency after 900 h of maximum power point (MPP) tracking under ISOS-L-1 standards.

Mixed tin–lead (Sn–Pb) perovskites have garnered considerable interest owing to their optimal bandgap, which facilitates the development of high-performance single-junction and all-perovskite tandem solar cells notwithstanding, far less attention has been paid to ion migration and remains inadequately understood. Here, we demonstrate that severe ionic migration still occurs within Sn–Pb perovskites, which severely undermines the performance and stability of devices. The diphenyliodonium hexafluorophosphate (DPIHFP) as an additive was introduced into the perovskite film to anchor I^– ions through electrostatic interactions. Besides, PF₆^– in DPIHFP could fill the iodine vacancies caused by I^– ions migration and react with perovskite via hydrogen bonding interactions. The activation energy for ion migration within the device increased from 0.37 to 0.51 eV after the introduction of DPIHFP. In consequence, the resultant mixed Sn–Pb devices achieved remarkable efficiencies of over 23%, along with enhanced long-term stability. Additionally, two-terminal all-perovskite tandems using DPIHFP-doped Sn–Pb perovskite devices as the bottom cells achieved an efficiency exceeding 28%.

Micro-light-emitting diodes (micro-LEDs) are widely recognized as a key technology for next-generation high-end displays; however, their commercialization remains limited by critical technical challenges, including the difficulty of achieving high-yield mass transfer of ultrasmall pixels (<2 μm) and the limited conversion efficiency and environmental stability of conventional color-conversion materials, such as quantum dots. Here, we present an integrated solution addressing these challenges by developing an organic–inorganic hybrid color-conversion material with high process compatibility, environmental friendliness, and excellent optical stability, combined with high-resolution photolithography for subpixel microarray patterning. This fabrication process requires no dry etching, significantly simplifying the workflow and reducing production time by over 3-fold. In addition, the integration of a narrowband color-purity enhancement film and scattering-assisted mixed-size nanoparticles further enhances color purity and color-conversion efficiency. In a ∼2 μm thick color-conversion layer, green and red conversion efficiencies reach 81.4 and 71.3%, respectively. Using this approach, single-color microarrays with 11,548 PPI and full-color microarrays with 5774 PPI at 1.4 × 1.4 μm subpixels were successfully fabricated. A color-gamut coverage of 144.16% for the DCI-P3 standard is also achieved. Under accelerated aging conditions (continuous exposure to 46,000 nits, peak 460 nm blue LED for 1000 h), the red and green conversion efficiencies decreased by less than 4%. These results demonstrate a key technological advancement for high-performance, full-color micro-LED displays.

Depth imaging, which provides crucial information about the distance of objects, plays a vital role in broad applications, such as autonomous driving, industrial manufacturing, and robotics. Traditional 3D imaging methods, for example, Time-of-Flight (ToF), usually require active illumination, which increases the complexity of the whole optical system. Passive depth imaging can be achieved using methods including stereo vision, light-field imaging, and point spread function engineering. Here, we have demonstrated a broadband achromatic double-helix metalens by employing the integrated resonant unit elements in metasurface, combining both the propagation phase with linear phase compensation and geometric phase. This broadband achromatic flat optical device effectively eliminated the chromatic aberration that occurs in the depth-sensing process of an existing double-helix metalens in the 1200–1400 nm wavelength range and achieved a 14.39-fold enhancement in energy utilization efficiency. Our work holds potential applications in various fields, including microscopic imaging, autonomous driving, and robotic perception.

The increasing demand for ultrafast data processing and high-density information storage necessitates photonic platforms capable of optical logic operations and multidimensional data encoding. However, most optical materials exhibit insufficient nonlinear absorption and limited tunability, preventing threshold-controlled switching for deterministic logic. Lanthanide-doped upconversion nanoparticles circumvent these limitations through discrete ladder-type manifolds, energy transfer, and strong nonlinear excitation pathways. Here, we report time-tuned photon avalanche upconversion in NaYF₄:Yb³⁺/Pr³⁺(15/0.5%)@NaYF₄ nanoparticles under 852 nm pulsed excitation as a reconfigurable platform for logic and encoding. By independently modulating the pulse width and frequency, we establish orthogonal control over avalanche kinetics and branching ratios. Long pulse widths promote excited-state population buildup, enhancing cross-relaxation-assisted feeding into higher-lying Pr³⁺ states and producing dominant blue emission. Conversely, high repetition frequencies reduce ground-state recovery, increase Yb³⁺ sensitizer recycling, and drive saturation-like regimes favoring red channels. Rate equation simulations corroborate the observed transitions in the emission color, temporal profile, and threshold behavior. Reversible color switching was demonstrated in both the photon avalanche and saturation regimes with tunable blue-to-red emission ratios. These dynamics enable optical logic gates and multidimensional encoding leveraging emission wavelength, lifetime, and temporal switching, establishing a framework for high-speed photonic computing and scalable high-capacity data encoding.

All-optical modulation and spectral encoding are significant for optical computing and information processing. However, the modulation level and efficiency of the traditional structure are limited by the size and uniformity of the modulation area and the insertion loss caused by on-chip coupling. A fiber optic integrated platform is proposed, which consists of single mode fiber (SMF), graded-index multimode fiber (GRIN-MMF), Ge₂Sb₂Te₅ (GST)-coated microspheres, and a tapered fiber coupler. The interface between the SMF and MMF achieves spatial mode expansion through multimode interference, significantly enlarging the modulation spot and enhancing the light material interaction. The platform exhibits stable and reversible spectral modulation, with transmission fluctuations of 0.29 (amorphous state) and 0.68 dB (crystalline state) under repeated measurements. The GST switching process exhibits a fast response, with crystallization and amorphization times measured at 263 and 164 ns, respectively. By integrating two microspheres, we achieved all-optical encoding of English letters, numbers, and symbols, successfully writing the characters “All-optical”. Furthermore, a dual-microsphere array is configured to realize basic optical logic gates (AND/OR) and 2 × 2 matrix-vector multiplication. This work proposes an architecture for integrating modulation, storage, and computing on a fiber-based photonic platform that paves the way toward scalable neuromorphic and memory photonic systems.