Achievingf ull-color emission from as ingle chromophore is not only highly desirable from practical considerations,but also greatly challenging for fundamental research. Herein, we demonstrated the density-dependent emission colors from as ingle boron-containing chromophore,f rom which multi-color fluorescent polyurethanes were prepared as well. Originating from its switchable molecular conformations, the emission color of the chromophore was found to be governed by the packing density and strongly influenced by hydrogen bonding interactions.T he chromophore was incorporated into polyurethanes to achievef ull-color emitting materials;t he emission color was only dependent on the chromophore density and could be tuned via synthetic approach by controlling the compositions.The emission colors could also be modulated by physical approaches,including by swelling/deswelling process,compression under high pressure, and even blending the fluorescent polyurethane with nonemitting ones.

Piezochromic luminescent (PCL) materials have attracted extensive research interest due to their potential applications in mechanosensors, ink-free printing, optical data storage, optoelectronic devices, etc. However, there is rarely report about...

Most atomically thin piezoelectrics suffer from weak piezoelectric response or current rectification along the thickness direction, which largely hinders their applications in a vertical crossbar architecture. Therefore, exploring new types of ultrathin materials with strong longitudinal piezoelectric coefficient and rectification is highly desired. In this study, the monolayer of van der Waals CuInP2S6 (CIPS) is successfully exfoliated and its strong piezoelectricity in the out‐of‐plane direction with an effective coefficient d33eff of ≈5.12 pm V−1, which is one or two orders of magnitude higher than that of most existing monolayer materials with intrinsic d33, is confirmed. A prototype vertical device is further constructed and the current rectification is achieved through the flexoelectricity induced by the scanning tip force. The switching between low and high rectification states can be readily controlled by tuning the mechanical loads. These findings manifest that CIPS possesses promising application in vertical nanoscale piezoelectric devices and provides a novel strategy for achieving a good current rectification in ultrathin piezoelectrics.

Achievingf ull-color emission from as ingle chromophore is not only highly desirable from practical considerations,but also greatly challenging for fundamental research. Herein, we demonstrated the density-dependent emission colors from as ingle boron-containing chromophore,f rom which multi-color fluorescent polyurethanes were prepared as well. Originating from its switchable molecular conformations, the emission color of the chromophore was found to be governed by the packing density and strongly influenced by hydrogen bonding interactions.T he chromophore was incorporated into polyurethanes to achievef ull-color emitting materials;t he emission color was only dependent on the chromophore density and could be tuned via synthetic approach by controlling the compositions.The emission colors could also be modulated by physical approaches,including by swelling/deswelling process,compression under high pressure, and even blending the fluorescent polyurethane with nonemitting ones.