Human eyes possess exceptional image sensing characteristics such as spectacularly wide field of view (FOV), high resolution and sensitivity with low aberration. Biomimetic eyes with the same superior characteristics are highly desirable in many technological applications. However, the spherical nature of biological eyes, particularly the core component of retina, poses an enormous challenge for fabrication of biomimetic eyes. Herein, we demonstrate a unique biomimetic electrochemical eye using a hemispherical retina made of high-density array of nanowires mimicking photoreceptors on a real retina. The device design has a high degree of structural similarity to a real human eye with potency to achieve a high imaging resolution when individual nanowires are electrically addressed. Meanwhile, image sensing function of our biomimetic eye device is also demonstrated. The work here may lead to a new generation of photosensing and imaging devices based on a bioinspired design that can benefit a wide spectrum of technological applications.

Alluring optical and electronic properties have made organometallic halide perovskites attractive candidates for optoelectronics. Among all perovskite materials, inorganic CsPbX (X is halide) in black cubic phase has triggered enormous attention recently owing to its comparable photovoltaic performance and high stability as compared to organic and hybrid perovskites. However, cubic phase stabilization at room temperature for CsPbI still survives as a challenge. Herein we report all inorganic three-dimensional vertical CsPbI perovskite nanowires (NWs) synthesized inside anodic alumina membrane (AAM) by chemical vapor deposition (CVD) method. It was discovered that the as-grown NWs have stable cubic phase at room temperature. This significant improvement on phase stability can be attributed to the effective encapsulation of NWs by AAM and large specific area of these NWs. To demonstrate device application of these NWs, photodetectors based on these high density CsPbI NWs were fabricated demonstrating decent performance. Our discovery suggests a novel and practical approach to stabilize the cubic phase of CsPbI material, which will have broad applications for optoelectronics in the visible wavelength range.

Metal halide perovskite has emerged as a promising material for light-emitting diodes. In the past, the performance of devices has been improved mainly by optimizing the active and charge injection layers. However, the large refractive index difference among different materials limits the overall light extraction. Herein, we fabricate efficient methylammonium lead bromide light-emitting diodes on nanophotonic substrates with an optimal device external quantum efficiency of 17.5% which is around twice of the record for the planar device based on this material system. Furthermore, optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate. These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes.