Qihao Jin

Reconstructive spectroscopy offers a promising route toward miniaturization by replacing dispersive optics with computational recovery from encoded measurements, but existing implementations typically rely on complex nanofabrication and highly decorrelated encoding elements, limiting manufacturability and robustness. Here, we demonstrate a reconstructive spectrometer based on inkjet‐printed interferometric optical filters featuring a minimalist tri‐layer architecture and high optical throughput. Contrary to prevailing design principles, we show that smooth, strongly correlated filter responses can nonetheless enable accurate spectral reconstruction over a 400 nm visible bandwidth. By adaptively selecting optimized subsets of filters using a custom genetic algorithm, the system exploits the high signal‐to‐noise ratio of correlated encoders while maintaining reconstruction fidelity. In addition, we introduce a calibration and reconstruction framework that requires only minimal a priori knowledge of the measured spectra, increasing the viability of practical deployment of reconstructive spectrometers. The resulting procedure combines scalable fabrication, adaptive encoding, and robust reconstruction, with a strong basis of versatile and manufacturing‐ready encoding elements.

Compact optical systems are revolutionizing precision measurement with their miniaturized design and functionality. At the forefront of this revolution are metalenses, composed of sub‐wavelength nanostructures. They have emerged as novel planar optical elements capable of replacing traditional bulky lenses in various compact optical applications. Meanwhile, single‐pixel imaging provides a cost‐effective, computation‐based method for achieving exceptional imaging quality. In this work, a metalens is integrated with a single‐pixel imaging architecture to project high‐resolution Hadamard patterns onto microscopic samples, replacing conventional lens‐to‐detector configurations. The system can simultaneously retrieve high‐quality amplitude and phase maps of micro targets, even under single‐photon‐level illumination conditions (1.7 photons/pixel/s). This breakthrough is ideal for biological samples, particularly in live cell imaging, where minimizing light exposure is critical to avoid photobleaching and phototoxicity. By delivering a cost‐effective, compact, and high‐performance solution, this system sets a new era for precision imaging in science and industry.

Optical interference filters (OIFs) are vital components for a wide range of optical and photonic systems. They are pivotal in controlling spectral transmission and reflection upon demand. OIFs rely on optical interference of the incident wave at multilayers, which are fabricated with nanometer precision. Here, we demonstrate that these requirements can be fulfilled by inkjet printing. This versatile technology offers a high degree of freedom in manufacturing, as well as cost-affordable and rapid-prototyping features from the micron to the meter scale. In this work, via rational ink design and formulation, OIFs were fully inkjet printed in ambient conditions. Longpass, shortpass, bandpass, and dichroic OIFs were fabricated, and precise control of the spectral response in OIFs was realized. Subsequently, customized lateral patterning of OIFs by inkjet printing was achieved. Furthermore, upscaling of the printed OIFs to A4 size (29.7 × 21.0 cm²) was demonstrated.

Perovskite nanocrystals (PNCs) bear a huge potential for widespread applications, such as color conversion, X-ray scintillators, and active laser media. However, the poor intrinsic stability and high susceptibility to environmental stimuli including moisture and oxygen have become bottlenecks of PNC materials for commercialization. Appropriate barrier material design can efficiently improve the stability of the PNCs. Particularly, the strategy for packaging PNCs in organosilicon matrixes can integrate the advantages of inorganic-oxide-based and polymer-based encapsulation routes. However, the inert long-carbon-chain ligands (e.g., oleic acid, oleylamine) used in the current ligand systems for silicon-based encapsulation are detrimental to the cross-linking of the organosilicon matrix, resulting in performance deficiencies in the nanocrystal films, such as low transparency and large surface roughness. Herein, we propose a dual-organosilicon ligand system consisting of (3-aminopropyl)triethoxysilane (APTES) and (3-aminopropyl)triethoxysilane with pentanedioic anhydride (APTES-PA), to replace the inert long-carbon-chain ligands for improving the performance of organosilicon-coated PNC films. As a result, strongly fluorescent PNC films prepared by a facile solution-casting method demonstrate high transparency and reduced surface roughness while maintaining high stability in various harsh environments. The optimized PNC films were eventually applied in an X-ray imaging system as scintillators, showing a high spatial resolution above 20 lp/mm. By designing this promising dual organosilicon ligand system for PNC films, our work highlights the crucial influence of the molecular structure of the capping ligands on the optical performance of the PNC film.

Key advances on triple-junction perovskite–perovskite–Si solar cells with an unprecedented efficiency of 24.4% and enhanced long-term thermal stability are reported via the development of high-performance middle perovskite solar cell.

3D‐printed conductive structures are highly attractive due to their great potential for customizable electronic devices. While the traditional 3D printing of metal requires high temperatures to sinter metal powders or polymer/metal composites, low or room temperature processes will be advantageous to enable multi‐material deposition and integration of optoelectronic applications. Herein, digital light processing technology and inkjet printing are combined as an effective strategy to fabricate customized 3D conductive structures. In this approach, a 3D‐printed nanoporous (NPo) polymeric material is used as a substrate onto which a nanoparticle‐based Ag ink is printed. SEM and X‐ray nano computed tomography (nanoCT) measurements show that the porous morphology of the pristine NPo is retained after deposition and annealing of the Ag ink. By optimizing the deposition conditions, conductive structures with sheet resistance −1 are achieved when annealing at temperatures as low as 100 °C. Finally, the integration of an inkjet‐printed photodetector is investigated based on an organic semiconductor active layer onto the NPo substrate. Thus, the potential of this approach is demonstrated for the additive manufacturing of functional 3D‐printed optoelectronic devices.

Inductively coupled plasma with an argon/hydrogen (Ar/H₂) mixture is a potential solution to many surface treatment problems, especially when encountering carbon contamination in optical X-ray and extreme ultraviolet instruments. Removing carbon contamination on multilayer thin films with Ar/H₂ plasma extends the lifetime of the above devices. To further investigate the reaction between plasma and carbon, both optical emission spectroscopy and finite element method with multiphysics fields were employed. The results demonstrated that the intensities of the Balmer lines were in good agreement with the densities of the radical hydrogen atoms from the simulation model, showing a dependence on the mixing ratio. At an electrical input power of 165 W and a total pressure of 5 Pa, an optimum mixing ratio of about 35 ± 5 % hydrogen produced the highest density of hydrogen radicals, coinciding with the highest carbon removal rate. This shows that the carbon removal with Ar/H₂ plasma was mainly controlled by the density of hydrogen radicals, and the mixing ratio showed a significant impact on the removal rates.

Microlens arrays (MLAs) have a variety of applications in, e.g., display systems, projection optics, and sensors. They can be manufactured by various fabrication methods. Among all, inkjet printing stands out because it offers a straightforward, versatile, and low‐cost fabrication route. However, extra manufacturing steps such as photolithography are so far involved to pre‐structure the substrate in order to improve the uniformity of the printed MLAs and achieve a high fill factor (FF). In this study, the fabrication of MLAs is reported on unstructured substrates by inkjet printing using an optimized UV‐curable ink on top of self‐assembled monolayers (SAMs). The latter allows for tuning the surface free energy and thus the aspect ratio of the microlenses. The high uniformity of the printed MLAs is demonstrated by the automatic quantitative evaluations, where the standard deviations of the radii are below 2.5% and of the sag heights are less than 3.9%. An unprecedented FF of 88% amongst all inkjet‐printed MLAs on unstructured substrates is achieved. Digitally controlled large area fabrication is demonstrated, both, on rigid as well as on flexible substrates, opening a pathway for customized microoptics by additive manufacturing.

Planar heterostructures are widely used in commercial III–V semiconductor lasers, but not yet explored for perovskite gain media. This study investigates the gain performance of a CsPbBr₃(BABr)_x/CsPbBr₃ (quasi‐2D/3D) perovskite planar heterostructure fabricated by lamination. The resulting heterostructure is designed to enhance the photon and excited‐state density in a non‐quantum‐confined thin 3D layer (30 nm) by simultaneously 1) confining the optical mode and 2) supporting excited‐state transfer from the wider‐bandgap quasi‐2D perovskite to the lower‐bandgap 3D perovskite. This allows the low amplified spontaneous emission (ASE) threshold of 150 (±20) µJ cm⁻² and lasing threshold of 46 (±15) µJ cm⁻² to be realized in such a heterostructure under nanosecond pumping. Further modeling reveals that the ASE performance can be significantly improved via maximizing the excited‐state transfer efficiency (only 14% for current prototypes) and highlights the potential of perovskite planar heterostructures as high‐performance gain media.