Moving a perovskite into the black: The bandgap of the black α-phase FAPbI ₃ (where FA is formamidinium) is nearly ideal for solar cells, but it is unstable with respect to the photoinactive yellow δ-phase. Lu et al. found that a film of the yellow phase was converted to a highly crystalline black phase by vapor exposure to methylammonium thiocyanate at 100°C, and it retained this structure after 500 hours at 85°C. Solar cells fabricated with this material had a power conversion efficiency of more than 23%. After 500 hours under maximum power tracking and a period of dark recovery, 94% of the original efficiency was retained. Science , this issue p. eabb8985

We report on efficient spin polarized injection and transport in long $\left({10}^2\text{nm}\right)$ channels of ${\text{Alq}}_3$ organic semiconductor. We employ vertical spin valve devices with a direct interface between the bottom manganite electrode and ${\text{Alq}}_3$, while the top-electrode geometry consists of an insulating tunnel barrier placed between the “soft” organic semiconductor and the top Co electrode. This solution reduces the ubiquitous problem of the so-called ill-defined layer caused by metal penetration, which extends into the organic layer up to distances of about 50–100 nm and prevents the realization of devices with well-defined geometry. For our devices the thickness is defined with an accuracy of about 2.5 nm, which is near the ${\text{Alq}}_3$ molecular size. We demonstrate efficient spin injection at both interfaces in devices with 100- and 200-nm-thick channels. We solve one of the most controversial problems of organic spintronics: the temperature limitations for spin transport in ${\text{Alq}}_3$-based devices. We clarify this issue by achieving room-temperature spin valve operation through the improvement of spin injection properties of both ferromagnetic/${\text{Alq}}_3$ interfaces. In addition, we discuss the nature of the inverse sign of the spin valve effect in such devices proposing a mechanism for spin transport.

The Internet of Things (IoT) has a broad vision of connecting every single object in the world to form one network. Flexible electronic devices, including RFIDs, sensors, memory devices, displays and power sources, are considered to be the technological basis of the IoT. The development of flexible electronic devices has been extremely rapid in the last decade. Many novel applications have been demonstrated, showing a strong potential impact on human life. In this review, we will summarize the recent progress in the research of flexible electronic devices and related flexible material within the framework of the IoT.