Smart luminescent materials that are responsive to external stimuli have received considerable interest. Here we report ionic iridium (III) complexes simultaneously exhibiting mechanochromic, vapochromic and electrochromic phosphorescence. These complexes share the same phosphorescent iridium (III) cation with a N-H moiety in the N^N ligand and contain different anions, including hexafluorophosphate, tetrafluoroborate, iodide, bromide and chloride. The anionic counterions cause a variation in the emission colours of the complexes from yellow to green by forming hydrogen bonds with the N-H proton. The electronic effect of the N-H moiety is sensitive towards mechanical grinding, solvent vapour and electric field, resulting in mechanochromic, vapochromic and electrochromic phosphorescence. On the basis of these findings, we construct a data-recording device and demonstrate data encryption and decryption via fluorescence lifetime imaging and time-gated luminescence imaging techniques. Our results suggest that rationally designed phosphorescent complexes may be promising candidates for advanced data recording and security protection. D ata recording, storage and security technologies have been widely utilized in economic and military fields as well as in our daily life. Smart luminescent materials that are responsive to external stimuli have received considerable attention in the construction of optical data recording and storage devices [1][2][3][4][5] . These materials have been classified on the basis of the types of external stimuli that they are responsive to. Mechanochromic materials show changes in emission colour in the presence of mechanical stimuli (for example, shearing, grinding and rubbing) because of the interruption of intermolecular interactions (for example, p-p stacking and hydrogen bonds) [6][7][8][9][10] . Vapochromic luminescence has been observed in materials that are responsive to volatile organic compounds 11,12 . Electric field is an important external stimulus. Electrochromism occurs in p-conjugated polymers because of the reversible transition between two redox states [13][14][15][16] . However, materials showing electrochromic luminescence, which is distinct luminescence colour responses to an electric field, are scarce. We envision the potential commercial applications of electrochromic luminescent materials because they can be conveniently integrated into semiconductor-based electronic devices. In addition, it is conceivable that compounds simultaneously showing mechanochromic, vapochromic and electrochromic luminescence are of great use to the development of multifunctional materials.Phosphorescent transition-metal complexes, such as those of Ir(III) and Pt(II), have been extensively studied for various photonic and electronic applications because of their rich excited-state properties, including high luminescence quantum yields, long emission lifetimes, large Stokes shifts, high photostability and various luminescence colours [17][18][19][20] . These complexes have also been utilized a...

Due to the advantages of good scalability, flexibility, low cost, ease of processing, 3D-stacking capability, and large capacity for data storage, polymer-based resistive memories have been a promising alternative or supplementary devices to conventional inorganic semiconductor-based memory technology, and attracted significant scientific interest as a new and promising research field. In this review, we first introduced the general characteristics of the device structures and fabrication, memory effects, switching mechanisms, and effects of electrodes on memory properties associated with polymer-based resistive memory devices. Subsequently, the research progress concerning the use of single polymers or polymer composites as active materials for resistive memory devices has been summarized and discussed. In particular, we consider a rational approach to their design and discuss how to realize the excellent memory devices and understand the memory mechanisms. Finally, the current challenges and several possible future research directions in this field have also been discussed.

A ternary polymer memory device based on a single polymer with on-chain Ir(III) complexes is fabricated by combining multiple memory mechanisms into one system. Excellent ternary memory performances-low reading, writing, and erasing voltages and good stability for all three states-are achieved.

The applications of conjugated polyelectrolytes in biosensing and bioimaging have attracted more and more research interests due to their excellent photophysical properties. In this work, a new series of conjugated polyelectrolytes containing long-lived phosphorescent Ir(III) complexes is designed and synthesized, which can be used for ratiometric and lifetime-based sensing of heparin utilizing the electrostatic interaction between cationic polymers and anionic heparin. By changing the ligand structures of Ir(III) complexes, the sensing performances of phosphorescent-conjugated polyelectrolytes (PCPEs) are optimized. In addition, the application of PCPEs in cellular imaging is carried out. These polymers can be applied for specific staining of cell membrane. Importantly, utilizing the long emission lifetime of phosphorescent signal of Ir(III) complexes, time-gated luminescent imaging is carried out, which can eliminate the short-lived background fluorescence interferences from the environment or biological samples.

Electrical stimuli‐induced change in absorption spectra, or electrochromism, has been well studied due to its promising applications in displays, sensors, smart windows, memory chips, and electronic papers, etc. However, electrochromic luminescent materials are rather scarce. In view of their advantages including easy tuning of luminescence color, short response time, and relatively high contrast, an electrochromic phosphorescent Ir(III) complex (IrOH) with an OH moiety in the N^N ligand is designed. This complex displays long‐lived phosphorescence, whose wavelength and lifetime are very sensitive to complex concentration, pH value, and electric field. Based on the interesting electrochromic phosphorescence of complex IrOH, a quasi‐solid information recording and storage device has been designed. A short‐lived fluorescent dye has been selected to encrypt the recorded information. In view of the much longer lifetime of IrOH compared with that of the fluorescent dye, decryption has been accomplished by using time‐resolved imaging techniques. Hence, it is believed that electrochromic phosphorescence will open up a new and efficient avenue for applications in information encryption and decryption.

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