Vision sensors are central to machine vision and intelligence. However, conventional planar devices rely on multielement optics and external processors to correct optical aberrations. This approach constrains miniaturization, reduces power efficiency and generally limits the field of view. Curved sensors can provide compact, aberration-corrected imaging, but their resolution has been below practicable levels. Here we present a bioinspired bionic eye system based on a hemispherical tandem artificial retina. This high curvature image sensor achieves a pixel density of 1,905 ppi with 367,500 total pixels, providing full-colour imaging across 300-800 nm and an aberration-corrected field of view exceeding 160°. Furthermore, the tandem design enables in-sensor, event-driven motion detection. Compared with frame-based imaging, this approach reduces the demand for bandwidth by over 99.95% and achieves a motion recognition accuracy of 98.6%. This work addresses the resolution bottleneck of hemispherical sensors and highlights their promise as compact, multifunctional vision applications.

Full-colour imagers are essential for capturing both spatial and spectral information, yet conventional architectures rely on broadband photodiodes integrated with passive colour filters, which introduce optical losses and constrain pixel density and colour fidelity. Here we report a full-colour perovskite imaging sensor based on the monolithic integration of inkjet-printed perovskite photodetector (PPD) arrays with a thin-film transistor (TFT) backplane. In this architecture, colour discrimination is achieved through vertically stacked perovskite photoactive and filter layers, enabling intrinsic narrowband photodetection without external optical filters. To realize high-resolution integration on TFT circuitry, we develop an inkjet-printing strategy based on controlled droplet dynamics, substrate superhydrophilicity and regulated nucleation/crystallization, which suppresses coffee-ring formation and enables uniform, defect-minimized perovskite micropatterns. The resulting active-matrix imager features 30 µm patterned perovskite pixels on a 160 µm Bayer-pattern pitch, corresponding to a 64 × 64 colour-pixel array with a resolution of 159 pixels per inch. The red, green and blue PPDs exhibit narrowband spectral selectivity over 570–750, 500–570 and 450–500 nm, respectively, together with high responsivity, low dark current, linear dynamic ranges of up to 24.83 dB, and self-powered operation with a − 3 dB bandwidth of 140 Hz. Using a custom-built readout platform, we further demonstrate faithful colour image acquisition and reconstruction. This work establishes inkjet-printed perovskite/TFT integration as a scalable route towards compact, lightweight and high-performance full-colour imaging systems.

Alkali metal doping has been widely utilized to regulate metal halide perovskites and improve their luminescence performance. However, due to the discordant tolerance factor caused by the smaller size of potassium and rubidium ions, it is still debatable whether they can be incorporated in the cesium perovskite crystal lattice. Here we provide unambiguous evidence for the formation of Rb+ and K+ substitutionally doped stable perovskite cubic crystal structure in the form of quantum wires embedded in nanoporous alumina template. The suppressed inner defects and enhanced exciton binding energy lead to a reduced non-radiative recombination in the co-doped perovskite quantum wires. The perovskite light-emitting diodes with a maximum external quantum efficiency of 17.5%, 21.2%, 24.9% and 30.1% and a maximum luminance of 1638 cd m-2, 3365 cd m-2, 13,483 cd m-2 and 31,706 cd m-2 for electroluminescence peak of 476 nm (primary-blue), 483 nm (sky-blue), 490 nm (sky-blue) and 512 nm (green) are fabricated respectively. Surprisingly, all devices emit high-color purity light with narrow linewidth of ≤16 nm.

Halide perovskite materials excel in broad optoelectronic applications, and there is an urgent demand to develop perovskite-based integrated optoelectronic devices. However, the limitations posed by the incompatibility of perovskite thin film with wet lithography greatly hinder its potential in many important applications, including ultrahigh-density displays, high-resolution image sensors, high-density memristors, and integrated photonic circuitry. To tackle this bottleneck problem, we develop the self-aligned close-spaced sublimation growth of perovskite quantum wires and demonstrate 0.18-micrometer feature size perovskite patterns, meanwhile achieving a pixel density of 63,500 pixels per inch, the highest reported for perovskite. We showcase pixelation of perovskite quantum wires with color conversion films, addressing the need for full-color microdisplays. In addition, we demonstrate these films on curved substrates, holding promise for near-eye microdisplays. Processes shown here can also apply to other perovskite devices such as high-resolution displays, image sensing, and memristor arrays.

Perovskite light-emitting diodes (PeLEDs) have experienced rapid development in the past 8 years. The external quantum efficiencies (EQEs) of red, green, and near-infrared (NIR) PeLEDs have all surpassed the 20% milestone. Meanwhile, the blue PeLEDs also achieved EQEs higher than 10% and are catching up quickly with PeLEDs of other colors. However, there are still two key problems remaining within the PeLEDs for their further development, namely the light extraction problem and the short lifetime problem. Therefore, in this report, we will discuss our recent work targeting addressing the above two critical problems. First, our work on improving the light extraction efficiency by deploying the nanophotonic substrates will be introduced. Second, the improvement of the device’s operational lifetime at high luminance conditions with perovskite nanowires embedded in a porous alumina template will be discussed. Third, a full evaporation method that is compatible with industrialization will be shown. Last but not least, our endeavors on the displays based on perovskite materials will be covered. References [1] Q. Zhang, M. M. Tavakoli, L. Gu, D. Zhang, L. Tang, Y. Gao, J. Guo, Y. Lin, S. -F. Leung, S. Poddar, Y. Fu, Z. Fan, "Efficient metal halide perovskite light-emitting diodes with significantly improved light extraction on nanophotonic substrates," Nature Communications, 10 (1), 727 (2019). [2] Q. Zhang, D. Zhang, L. Gu, S. Poddar, Y. Fu, L. Shu, and Z. Fan, “Three-dimensional perovskite nanophotonic wire array-based light-emitting diodes with significantly improved efficiency and stability,” ACS Nano, 14 (2), 1577-1585 (2020). [3] Y. Fu, Q. Zhang, D. Zhang, Y. Tang, L. Shu, Y. Zhu, and Z. Fan, “Scalable All-evaporation Fabrication of Efficient Light-Emitting Diodes with Hybrid 2D-3D Perovskite Nanostructures,” Advanced Functional Materials, 30, 2002913 (2020). [4] D. Zhang, Q. Zhang, B. Ren, Y. Zhu, M. Abdellah, Y. Fu, B. Cao, C. Wang, L. Gu, Y. Ding, K.-H. Tsui, S. Fan, S. Poddar, L. Shu, Y. Zhang, D.-B. Kuang, J.-F. Liao, Y. Lu, K. Zheng, Z. He, Z. Fan, “Large-scale Planar and Spherical Light-emitting Diodes Based on Arrays of Perovskite Quantum Wires”, Nature Photonics, 19, 284-290 (2022).

Within a short span of a few years, metal halide perovskite light-emitting diodes (LEDs) have shot past the 20 percent external quantum efficiency mark. As the material quality and photoluminescent quantum yield of perovskite are already at par with the state-of-the-art, light extraction for further quantum efficiency enhancement has taken the center stage of scientific interest. Herein, we demonstrate horizontally aligned perovskite nanowire-based light-emitting diodes with 50.9 percent of light extraction efficiency, with a 2.9-fold increase compared to the planar counterpart. The absorption spectra of the plane wave incidence exhibit the weak trapping of light within the emission range. Purcell factors of horizontal perovskite nanowires with different diameters are also studied, which provides design guidelines for applying the horizontally aligned perovskite nanowires for multifarious optoelectronic applications such as lasing. The resonance peak positioned at 530 nm wavelength shows the nanowire antennas’ effect in the nanowires with diameters of 300 nm, 500 nm, and 550 nm respectively. Furthermore, the fabrication process of the light-emitting devices based on ink-jet printing has also been proposed. This report not only provides an in-depth understanding of light extraction in nanowire LEDs but also heralds the inception of horizontally aligned perovskite nanowire-based optoelectronic devices.

Metal halide perovskite Light-emitting Diodes (LEDs) have achieved 20% EQE in only five years. As the material quality and photoluminescent quantum yield of perovskite are already high, light extraction appears to be the next common challenge for further EQE enhancement. We substantially demonstrated a horizontal perovskite nanowire LED with 50.9% of light extraction, with an enhancement of 2.9-fold compared to the planar counterpart. The device will be fabricated through ink-jet printing.

In the past a few years, perovskite light-emitting diodes (LEDs) have experienced extremely amazing development. Thanks to the decent optoelectronic properties, perovskite material has made itself a competitive candidate for next-generation displays and lighting. With the great efforts of researchers in this field, the external quantum efficiencies (EQEs) have already surpassed the 20% milestone for both red and green colored perovskite LEDs. Lately, the blue perovskite LEDs have been reported to achieve an EQE higher than 12%. With the fantastic material quality, perovskite material can achieve a super high photoluminescent quantum efficiency (PLQY); therefore, the internal quantum efficiency (QE) for perovskite LEDs can also reach the level of higher than 90%. As a result, the key solution to the further enhancement of the perovskite LEDs performance relies on the light outcoupling for perovskite LEDs. During the past five years, we have devoted ourselves to the development of nanophotonic strategies for the performance enhancement of the perovskite LEDs. The strategies are comprised of two main categories. The first category is using a nanophotonic substrate for perovskite LEDs devices. The structure we designed was a combination of a nanodome coupler with the photonic crystal optical antennas. When the geometry of the structure was delicately optimized, the light supposed to be trapped inside the active layer can be first coupled into the photonic crystals and form guided modes. After that, the photonic crystals, working as optical antennas, can convert the guided modes to the leaky modes and finally the leaky modes can emit to the air. With this strategy, we successfully improved the EQE of the perovskite LEDs from about 8% to 17.5%, which was the record for the MAPbBr3 based perovskite LEDs at that time. The second category of the nanophotonic strategies is making nanostructured active materials instead of using the nanostructured out-coupling substrates. With the exploration of varieties of nanostructures, we finally determined to use the nanowire arrays for the perovskite LEDs study. Intriguingly, we came up with a solution method with the nanoporous template for perovskite nanowires growth. By studying the growth with different template geometries, we found out that the nanowire growth had a strong relationship with the capillary effect. Then we carefully designed the template thickness and the nanowire lengths, and we made the three-dimensional nanowire arrays-based perovskite LEDs. Compared to the planar counterparts, the nanowire-based perovskite LEDs showed an enhanced EQE (from 11% to 16%), which is due to the improved light coupling inside the nanowires (from about 20% to about 45%). More importantly, the operational stability of the nanowire-based perovskite LEDs was also enhanced (T50 increased from 9 min to 35 min). And the long-term stability of the nanowire-based perovskite LEDs was also increased with an enhancement factor of 3 times. It’s also worth noting that, the mechanical robustness of the nanowire-based perovskite LEDs was also enhanced a lot due to the protection by the porous template, and much fewer cracks were created inside nanowires during bendings when compared to the planar counterparts. With the above mentioned two nanophotonic strategies for perovskite LEDs performance (both light-coupling efficiency and stability) enhancement, we demonstrated the advantages of applying nanostructures in perovskite LEDs. By further developing the perovskite material qualities and meanwhile improving the deposition techniques that are more compatible with nanostructures, we believe the EQEs of perovskite LEDs can be further improved to a new milestone soon. Last but not least, the nanophotonic strategies we developed here are not just limited to LEDs; they can be also applied for other device applications such as solar cells, photodetectors, and lasers.