Purely organic room temperature phosphorescence (RTP) has attracted wide attention recently due to its various application potentials. However, ultralong RTP (URTP) with high efficiency is still rarely achieved. Herein, by dissolving 1,8-naphthalic anhydride in certain organic solid hosts, URTP with a lifetime of over 600 ms and overall quantum yield of over 20% is realized. Meanwhile, the URTP can also be achieved by mechanical excitation when the host is mechanoluminescent. Femtosecond transient absorption studies reveal that intersystem crossing of the host is accelerated substantially in the presence of a trace amount of 1,8-naphthalic anhydride. Accordingly, we propose that a cluster exciton spanning the host and guest forms as a transient state before the guest acts as an energy trap for the RTP state. The cluster exciton model proposed here is expected to help expand the varieties of purely organic URTP materials based on an advanced understanding of guest/host combinations.

The unique advantages and the exciting application prospects of AIEgens have triggered booming developments in this area in recent years. Among them, stimuli‐responsive AIEgens have received particular attention and impressive progress, and they have been demonstrated to show tremendous potential in many fields from physical chemistry to materials science and to biology and medicine. Here, the recent achievements of stimuli‐responsive AIEgens in terms of seven most representative types of stimuli including force, light, polarity, temperature, electricity, ion, and pH, are summarized. Based on typical examples, it is illustrated how each type of systems realize the desired stimuli‐responsive performance for various applications. The key work principles behind them are ultimately deciphered and figured out to offer new insights and guidelines for the design and engineering of the next‐generation stimuli‐responsive luminescent materials for more broad applications.

drawbacks. In addition to the higher material costs of these rare-earth metals, many inorganic LPLs require harsh synthetic procedures, [11] further increasing research costs. Organic LPL (OLPL) materials, [12][13][14][15][16] offer the promise of a multitude of benefits: easier synthesis, easier modification for targeted functionality, and easier processing. However, the development of OLPL materials has encountered many obstacles. To access long lived states in organic compounds, there have been many designs to exploit the excited triplet state. Though access to and from the triplet state is a forbidden process and once thought to be too inefficient for effective use at room temperature, [17] recent advances have vastly increased intersystem crossing efficiency by enhancing spin-orbit coupling (SOC) with the use of heteroatoms, [18,19] the carbonyl functional group, [20][21][22] heavy atom effects, [23][24][25][26][27] and multimer-enhanced intersystem crossing. [28][29][30][31][32] Equally important is protecting the long-lived triplet after its generation, due to the fact that they are particularly sensitive to molecular vibrational quenching and atmospheric oxygen. In this regard, recent works have accomplished this through the use of crystals, [33,34] metal-organic frameworks, [35] H-aggregation, [36] and others. [30,32,37] Although there have been many achievements in generating organic room-temperature Because of their innate ability to store and then release energy, longpersistent luminescence (LPL) materials have garnered strong research interest in a wide range of multidisciplinary fields, such as biomedical sciences, theranostics, and photonic devices. Although many inorganic LPL systems with afterglow durations of up to hours and days have been reported, organic systems have had difficulties reaching similar timescales. In this work, a design principle based on the successes of inorganic systems to produce an organic LPL (OLPL) system through the use of a strong organic electron trap is proposed. The resulting system generates detectable afterglow for up to 7 h, significantly longer than any other reported OLPL system. The design strategy demonstrates an easy methodology to develop organic long-persistent phosphors, opening the door to new OLPL materials.Long-persistent luminescent [1,2] (LPL) materials have demonstrated great potential and performance in multiple areas, such as life sciences, [3] the biomedical field, [2,4] and photo voltaics, [5] as they offer fascinating possibilities for their ability to store and slowly release excited state energy. For example in biomedical applications, LPL materials can be used postexcitation, overcoming any issue of autofluorescence. [6][7][8] Currently, the most successful LPL materials make use of transition and rare-earth metal ions. [9,10] Although the metals grant exceptionally long afterglows that range from minutes to hours, with some systems lasting days and weeks, [11] they are not without their inherentThe ORCID identification number(s) for the aut...