The research of organic luminescent materials in aggregate has drawn more and more attention for their wide applications. To adjust the luminescent properties for aggregates, a deep understanding of the corresponding internal mechanism is needed. In this short review, a brief introduction of aggregation‐induced emission (AIE) and some other solid state luminescence behaviors derived from or parallel to AIE is presented. Particularly, the relationship between emission property and intermolecular/intramolecular interactions is summarized, with the aim to guide the further development of organic optoelectronic materials in aggregate.

The research of purely organic materials with long afterglow has drawn more and more attention, especially for those with stimulus-response characteristic. So far, this kind of material is really very scarce and their performance is not good enough. In this study, we successfully developed an efficient heatingresponsive room-temperature phosphorescence material with phosphorescence efficiency and lifetime up to 13.4% and 2.08 s through the simple host-guest doping strategy. Further on, by introducing the additional energy acceptor of fluorescein with concentration-dependent emission to construct ternary doping systems, the afterglow color was extended from blue to yellow. Accordingly, the multicolor thermal printings have been easily realized, showing the great practical application prospects.

Conspectus Room temperature phosphorescence (RTP) materials, which could respond to external stimuli, such as force, heat, light, electric filed, etc., have drawn increasing attention for their broad application prospects, especially in the fields of anticounterfeiting, sensors, data storage, and so on. In comparison with the traditional fluorescence ones, RTP materials show much longer emission lifetimes, which can be even caught by the naked eye. Thus, the change in emission lifetime under an external stimulus for RTP materials can be also a potential monitoring parameter, in addition to emission color and intensity. In other words, the number of visual monitoring parameters could increase from two to three in RTP materials, which would greatly facilitate their practical applications. Until now, RTP materials have been typically limited to metal-containing inorganic materials, particularly rare-earth phosphors. Their emissions are governed by the slow liberation of trapped charge carriers from isolated traps of impurities, defects, or ions through thermal stimulation with low luminescence efficiency. However, these materials suffer from some intrinsic disadvantages, including high cost, potential toxicity, and instability in aqueous environments. In order to solve these problems, the purely organic RTP materials should be a good choice. However, these kinds of materials are really scarce now, especially for the ones with stimulus response characteristic. To develop purely organic RTP materials with a stimulus response effect, we and other scientists have tried a lot. Luckily, some progresses have been made. In this Account, we present our recent progress on the stimulus-responsive room temperature phosphorescence of organic materials, mainly focusing on the internal mechanism and potential applications. First, the fundamental knowledge is described to illustrate the importance and main principles of the stimulus-responsive RTP effect. Then, some typical stimulus-responsive RTP materials based on different internal mechanisms are discussed. Mainly, two kinds of stimulus-responsive RTP materials were introduced, namely, single-component and multicomponent ones. Correspondingly, their dynamic change of the RTP property under external stimulus occurred based on the distinct internal mechanisms. For single-component materials, the changes in molecular structure, packing, or conformation, have played a significant role in their corresponding stimulus-responsive RTP effect. As for multicomponent materials, the changed oxygen concentration in matrix and intermolecular distance between different components were found more during the stimulus-responsive RTP process. Accordingly, different potential applications were explored based on the different stimulus-responsive RTP processes. With the classification of stimulus-responsive RTP materials based on different internal mechanisms, the corresponding design strategy could be well proposed, thus guiding the further development of this research field.

A structure based on a bipolar transport/emitting layer is proposed and implemented for making organic light-emitting diodes. Compared to the conventional heterojunction organic light-emitting diodes, more than a factor of six improvement in device reliability (a projected operating lifetime of 70 000 h) is achieved in the structure. The significant improvement in device lifetime is attributed to the elimination of the heterointerface present in the conventional devices which greatly affects the device reliability.

Three types of urethane-acrylate IPN's, two sequential and one simultaneous, were prepared in which the urethane was formed under thermal polymerization; and the acrylate, by photopolymerization. The IPN morphologies were studied by transmission electron microscopy (TEM) and dynamic mechanical analysis (DMA). When the urethane was reacted to relatively high conversion prior to photoinitiation of the acrylate, the IPN's obtained were characterized by very small domain sizes (<20 nm) and a single Tg between those of the two components. When the acrylate polymerization was induced following much smaller conversion of the urethane, or if the acrylate was polymerized first, domains of larger size (>100 nm) were obtained. In these two instances, if the Tg's of the individual components are well separated, dynamic mechanical analysis indicated separate Tg values close to the Tg's of the individual components. The degree of phase mixing in each IPN was estimated from the Tg values from the Fox equation, and these correlate with the various processing conditions.