Transparent ultraviolet (UV) photodetectors are an essential component of nextgeneration "see-through" electronics. However, the current photodetectors often suffer from relatively slow response speeds and high driving voltages. Here, all-solution-processed UV photodetectors are reported that are facilely prepared from environmentally friendly and abundant materials. The UV photodetectors are composed of a titanium dioxide thin film as the photosensitive layer sandwiched between two different transparent electrodes to form asymmetric Schottky junctions. The photodetector with high optical transparency can operate at zero bias because of spontaneous separation of photogenerated electron-hole pairs by the built-in electric field. The resulting self-powered photodetector displays high sensitivity to broadband UV light (200-400 nm). In particular, an ultrafast response speed up to 44 ns is obtained, representing a significant improvement over those of the conventional transparent photodetectors. Moreover, the photodetector has been successfully applied, for the first time, in a UV communication system as the self-powered signal receiver. This work uniquely combines the features of high optical transparency and self-power ability into UV photodetectors and would enable a broad range of optoelectronic applications.

A much simplified electrochromic structure for smart windows and ionic writing boards is designed based on a multifunctional hydrogel.

Methylammonium lead iodide perovskite (MAPbI 3 ) has made a re-entry into the literature nowadays for its extraordinary characteristics, such as high absorption of light, long carrier diffusion length, high carrier mobility, low trap-state density, low surface recombination velocity and ease of attainment. Here, we report a self-powered photodetector based on a CH 3 NH 3 PbI 3 single crystal by employing asymmetric Au-Al electrodes. The key issue of this photodetector was the metal-semiconductor contacts, owing to the Schottky junction between them. By setting the channel length between the Au-Al electrodes to 30 μm for sufficient electron-hole pair separation and transportation, the device showed good performance under 1 sun illumination. The short-circuit photocurrent density and open-circuit voltage were 6.86 mA cm −2 and 0.7 V, respectively. The photocurrent was almost 2 orders of magnitude larger than that based on a perovskite polycrystalline film with a similar device structure. More importantly, the device could detect the lowest noticeable incident power density down to 1 × 10 −8 W cm −2 . Under this weak light intensity, the responsivity was as high as 0.24 A W −1 without any bias. The photoresponse also had a broadband ranging from 375 nm to 808 nm accompanied by a fast response speed.

The integration of a CH3NH3PbI3 single crystal photodetector with a TENG leads to a self-powered photodetector with a large responsivity and a wide detection range.

As an alternative technology, stretchable electronics attract long‐lasting attention. A newly‐designed stretchable nanogenerator with unique dual‐mode energy conversion is reported. The ability of converting the input mechanical stimuli to either electric or light output is achieved by monolithically integrating a transparent single‐electrode triboelectric nanogenerator (S‐TENG) with a ZnS based mechanoluminescence (ML) composite. This stretchable device with versatile functions promotes the development of the smart systems to efficiently and diversely utilize ubiquitous mechanical energy and demonstrates great potential for artificial e‐skins.