Organic materials with long‐lived, color‐tunable phosphorescence are potentially useful for optical recording, anti‐counterfeiting, and bioimaging. Herein, we develop a series of novel host–guest organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra‐long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color‐tunable inks have already been developed using visible dyes, solution‐processed security inks that are temperature dependent and display time‐resolved printed images are unprecedented. This strategy can provide a crucial step towards the next‐generation of security technologies for information handling.

Figure 2. Steroid based host matrix in realizing RTP emission. (a) Chemical structures of steroid host and second amino-substituted deuterated carbon as well as the design principle in realizing the RTP emission. Reproduced with permission. 39 Copyright 2013, Wiley. (b) Chemical structures of host 4, guest 3, and dispersant 5 as well as the application in thermal reversible recording materials. Reproduced with permission. 40 Copyright 2013, Wiley. (K r = phosphorescent decay rate, K q = rate of quenching long-lived triplet excitons).

A water-soluble, 'turn-on' fluorescent chemosensor based on aggregation-induced emission (AIE) has been developed. It exhibits rapid response, excellent selectivity, and sensitivity to Al(3+).

Organic host-guest doping materials with room temperature phosphorescence (RTP) phenomenon have attracted considerable attention. However, it was still challenging to investigate their corresponding luminescence mechanism, because host-guest system very difficult...

The control of the emission properties of doping materials through molecular design makes organic materials potentially promising candidates for many optoelectronic applications and devices. However, organic doping systems with high quantum yields and persistent luminescence processes have rarely been reported, and their luminescence mechanisms are still not well established. Here we developed a series of purely organic heavy-atom-free doping systems. The guest molecules can dope either donor or acceptor matrixes, both leading to an enhanced fluorescence (Φ = 63−76%) and room-temperature phosphorescence (Φ = 7.6−14.5%, τ = 119−317 ms) under ambient conditions. XRD measurements and density functional calculations results indicated ultralong phosphorescence was determined by both the cocrystalline state and the energy levels between the host and guest materials. The doping materials are fairly stable to light, heat, and humidity. This work may provide unique insight for designing doping systems and expanding the scope of organic phosphorescence applications.