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.

The bulky footprint of near-infrared (NIR) spectrometers has been limiting their applications in portable and movable systems for probing molecular compositions and structures. Quantum dot (QD) computational spectrometers are a promising strategy for miniaturized NIR spectrometers, whose performance is limited by the poor spectral encoding matrix and, ultimately, the poor quality of PbS QDs. Here, we show that the monodispersity and finely controlled absorption peak of PbS QDs are critical parameters affecting the spectral resolution and noise resistance. Thus, a facile synthesis of a series of monodisperse PbS QDs from a single batch is developed using cation exchange synthesis in a seeded-growth manner. All the as-synthesized PbS QDs have narrow size distributions of below 4%, and the peak intervals can be controlled to within 3 nm. Furthermore, stable PbS QD inks are prepared by considering the compatibility between QD ligands, solvents, and polymers. The PbS QD filter array is fabricated using a contact printing method, exhibiting supreme transmittance curves and a spectral encoding matrix. The filter array is coupled with an InGaAs image sensor to form the QD NIR computational spectrometer. Thanks to the high-quality PbS QDs, the QD spectrometer shows a high spectral resolution of 1.5 nm in a broad wavelength range of 900-1700 nm and excellent spectral reconstruction of narrow and broad spectra with fidelities of above 0.987. Additionally, the QD spectrometer is applied to distinguish materials and accurately measure the alcohol content of white wines, demonstrating the great potential for practical applications of QD NIR spectrometers.

As promising optoelectronic materials, lead sulfide quantum dots (PbS QDs) have attracted great attention. However, their applications are substantially limited by the QD quality and/or complicated synthesis. Herein, a facile new synthesis is developed for highly monodisperse and halide passivated PbS QDs. The new synthesis is based on a heterogeneous system containing a PbCl₂-Pb(OA)₂ solid-liquid precursor solution. The solid PbCl₂ inhibits the diffusion of monomers and maintains a high oversaturation condition for the growth of PbS QDs, resulting in high monodispersities. In addition, the PbCl₂ gives rise to halide passivation on the PbS QDs, showing excellent stability in air. The high monodispersity and good passivation endow these PbS QDs with outstanding optoelectronic properties, demonstrated by a 9.43% power conversion efficiency of PbS QD solar cells with a bandgap of ~ 0.95 eV (1,300 nm). We believe that this heterogeneous strategy opens up a new avenue optimizing for the synthesis and applications of QDs.

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.