Daoli Zhang

Cation-exchange synthesis produces monodisperse PbS quantum dots (QDs), yet its central limitation─precursor preparation and dropwise injection─is usually treated as a practical issue. Here, we recast it as sulfur chemical-potential programming; that is, ethyl ziram (EZ) serves as a dynamic sulfur reservoir (DSR) whose thermolysis continuously evolves sulfur activity during growth. This reservoir couples ZnS QD seeds with reservoir-fed growth, shifting the reaction from externally injected templates to an internally regulated kinetic regime, where QD size is set by the balance between seed density and EZ-derived sulfur replenishment. The DSR route yields short-wave infrared PbS QDs tunable from 1200 to 2200 nm, with narrow size distributions, high reproducibility, and reduced synthetic burden. Photodetectors show 64.7% external quantum efficiency and 5.8 × 1012 Jones detectivity, and 640 × 512 CMOS-integrated imaging chips exhibit a 0.04% bad-pixel rate and 3.78% photoresponse nonuniformity, validating DSR as a strategy for high-quality QD synthesis.

Lead selenide (PbSe) quantum dots (QDs) are promising candidates for short‐wave infrared (SWIR) photodetectors; however, their performance is fundamentally limited by surface trap states and environmental instability. Constructing core/shell heterostructures offers a potential solution, yet a critical challenge remains in optimizing the shell to strike a synergistic balance between effective defect passivation and efficient carrier transport. Herein, we report a precise cation‐exchange epitaxial growth strategy to synthesize highly monodisperse PbSe/PbS core/shell QDs with tunable shell thickness. We systematically elucidate the structure‐property relationships, revealing that thicker PbS shells significantly suppress non‐radiative recombination and extend carrier lifetimes. By tailoring the shell thickness to an optimal regime, we achieve a high‐quality QD solid that minimizes trap density while maintaining superior carrier mobility. Consequently, the optimized SWIR photodetector exhibits a high external quantum efficiency (EQE) of 49% at 0 V and a specific detectivity of 2.37 × 10 ¹² Jones at 1650 nm. Furthermore, this robust architecture enables the extension of spectral response into the extended SWIR region (up to 2.5 µm) and facilitates the demonstration of high‐resolution SWIR imaging. This work provides a generic design principle for engineering high‐performance infrared optoelectronics through precise modulation of heterostructure nanomaterials.

Micro-light-emitting diodes (micro-LEDs) have emerged as a promising display technology featuring high resolution, wide color gamut, high contrast, flexibility, and long lifetime. However, there are severe challenges in full-color micro-LED, such as low efficiencies of red and green micro-LEDs, complex driving circuits for three-color micro-LEDs, and challenging mass transfer. Thus, converting blue light into red and green light by coupling color converters with blue LEDs is a reasonable strategy. Colloidal quantum dots (QDs) are an optimal candidate for color converters due to their high photoluminescence quantum yield, narrow emission peaks, small particle sizes, and solution processibility. Therefore, full-color micro-LEDs based on quantum dot color converters are attracting increasing attention. This review introduces micro-LED technology and the research progress of the full-color realization, and describes the associated technical challenges. Furthermore, it outlines the properties of QDs, patterning techniques, integration with micro-LEDs for achieving full color, and finally analyzes the challenges of applying QDs to micro-LEDs, demonstrating the application potential of QDs in achieving full-color of micro-LEDs, along with prospects for addressing current challenges.

Low-dimensional metal halides with broadband emissions are expected to serve as downconversion luminescent materials for solid-state lighting (SSL). However, efficiently generating full-spectrum white-light emission with a high color-rendering index (CRI) in single-phase emitters remains a challenge. Here, we report a novel zero-dimensional (0D) hybrid mixed-metal halide (TPA)₂CuAgI₄ (TPA = tetrapropylammonium), in which individual [CuAgI₄]^2- dimers are completely isolated and surrounded by the organic cations TPA⁺. Cu⁺ and Ag⁺ share the same crystallographic site in [CuAgI₄]^2- dimers with the same statistical probability. Upon photoexcitation, single crystals exhibit a full-spectrum white-light emission with a full width at half-maximum (fwhm) of up to 314 nm and a high quantum efficiency of 46.8%. Detailed photophysical studies and theoretical calculations reveal that the ultra-broadband emission of (TPA)₂CuAgI₄ originates from the radiative recombination of red-, green-, and blue-emitting self-trapped excitons in [CuAgI₄]^2- dimers. In addition, (TPA)₂CuAgI₄ nanocrystals were successfully synthesized and exhibited optical properties similar to those of single-crystal counterparts. Finally, a prototype ultraviolet (UV)-pumped white-light-emitting diode (WLED) and a composite thin film employing this new white-light emitter produces a well-distributed full-spectrum white light with a high CRI of 91.4 and a warm correlated color temperature (CCT) of 4135 K, indicating the potential application of this white-light emitter in SSL. These results provide a new perspective for designing superior single-phase white-light emitters.

Infrared (IR) solar cells are promising devices for improving the power conversion efficiency (PCE) of conventional solar cells by expanding the utilization region of the sunlight spectrum to near-infrared range. IR solar cells based on colloidal quantum dots (QDs) have attracted extensive attention due to the widely tunable absorption spectrum controlled by dot size and the unique solution processibility. However, the trade-off in QD solar cells between light absorption and photo-generated carrier collection has limited the further improvement of PCE. Here, we present high-performance PbS QD IR solar cells resulting from the combination of boosted light absorption and optimized carrier extraction. By constructing an optical resonance cavity, the light absorption is significantly enhanced in the range of 1,150–1,300 nm at a relatively thin photoactive layer. Meanwhile, the thin photoactive layer facilitates efficient carrier extraction. Consequently, the PbS QD IR solar cells exhibit a highly efficient photoelectric conversion in the IR region, resulting in a high IR PCE of 1.3% which is comparable to the highest value of solution-processed IR solar cells based on PbSe QDs. These results demonstrate that constructing an optical resonance cavity is a reasonable strategy for effective conversion of photons in the devices aiming at light in a relatively narrow wavelength range, such as IR solar cells and narrow band photodetectors.

Because of their moderate penetration power, β-rays (high-energy electrons) are a useful signal for evaluating the surface contamination of nuclear radiation. However, the development of β-ray scintillators, which convert the absorbed high-energy electrons into visible photons, is hindered by the limitations of materials selection. Herein, we report two highly luminescent zero-dimensional (0D) organic—inorganic lead-free metal halide hybrids, (C₁₃H₃₀N)₂MnBr₄ and (C₁₉H₃₄N)₂MnBr₄, as scintillators exhibiting efficient β-ray scintillation. These hybrid scintillators combine the superior properties of organic and inorganic components. For example, organic components that contain light elements C, H, and N enhance the capturing efficiency of β particles; isolated inorganic [MnBr₄]²⁻ tetrahedrons serve as highly localized emitting centers to emit intense radioluminescence (RL) under β-ray excitation. Both hybrids show a narrow-band green emission peaked at 518 nm with photoluminescence quantum efficiencies (PLQEs) of 81.3% for (C₁₃H₃₀N)₂MnBr₄ and 86.4% for (C₁₉H₃₄N)₂MnBr₄, respectively. To enable the solution processing of this promising metal halide hybrid, we successfully synthesized (C₁₃H₃₀N)₂MnBr₄ colloidal nanocrystals for the first time. Being excited by β-rays, (C₁₃H₃₀N)₂MnBr₄ scintillators show a linear response to β-ray dose rate over a broad range from 400 to 2,800 Gy·s⁻¹, and also display robust radiation resistance that 80% of the initial RL intensity can be maintained after an ultrahigh accumulated radiation dose of 240 kGy. This work will open up a new route for the development of β-ray scintillators.

Stimulated by the attractive performance of multi-dimensional heterostructures involving hexagonal boron nitride ( h BN), intense attentions have been paid to creation of sharp boundary/interface, which could bring h BN nano-structures additional appealing physical properties. However, the lack of controllable synthesis limits further experimental investigation on h BN nano-structures. Here, the directional etching of transitional metal nano-particles (NPs) on the surface of h BN to produce nano-trenches with sharp edges was systematic investigated. It is found that, only Pt and Ir NPs can produce armchair-oriented nano-trenches at low H ₂ partial pressure, while other transitional metals lead to zigzag oriented nano-trenches. The density and width of the nano-trenches always increase with etching temperature and the pre-treated solution concentration while the trench orientation depends on both H ₂ partial pressure and etching temperature. The aspect ratio of nano-trenches may reach several thousand under optimized conditions. The method exhibited here shines a light on edge-selective patterning of 2D crystals.