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Herein, a series of carbon dot composites (CDC) with full-color and long-lived room-temperature phosphorescence (RTP) are prepared by a simple solid-phase one-step method from a single non-conjugated and non-aromatic carbon source. The RTP emission wavelength can be adjusted from 462 to 623 nm by changing the feeding ratio and reaction temperature. The luminescent lifetime and quantum yield of a green emissive CDC (AB-CDC-3) reach 1.1 s and 39%, respectively, because of the close interaction between carbon dots and inorganic matrix. Due to the existence of multiple luminescent centers, these CDC exhibit excitation wavelength-dependent RTP and a white emission when excited at a specific wavelength. A single-component afterglow luminescent diode based on AB-CDC-4 shows a high-quality white emission with CIE of (0.30, 0.33) and color-rendering index of 88. Based on the unique photophysical properties of the composites, they exhibit huge application potential in the field of multilevel anti-counterfeiting, fingerprint identification, and optoelectronic devices.

Synergism between covalent and non-covalent bonds is employed to fix an organic phosphor guest in a rigid inorganic framework, simulating the stiffening effect seen in the glassy state and realizing efficient and ultralong room-temperature phosphorescence (RTP). Twelve heavy-atom-free composites have been obtained through introducing arylboric or arylcarboxylic acid derivatives into the inorganic boric acid matrix by solid-phase synthesis. Owing to the stiffening effect of multiple bonds, all the composites show highly efficient and persistent RTP of guest molecules with a quantum yield ranging from 39.8 % to ca. 100 % and a lifetime up to 8.74 s, which results in a 55 s afterglow visible to the naked eye after exposure to a portable UV lamp. Interestingly, it is found that the substitution position and quantity of carboxyl in the guest have a great influence on the phosphorescent properties, and that the heavy-atom effect is invalid in such host-guest hybrid systems. The 100 g grade composite is easily prepared because of the solvent-free, green, and simple synthesis method. These results provide an important way for the development of RTP materials with ultrahigh quantum yield and ultralong lifetime, as well as their practical applications in the fields of anti-counterfeiting and information storage, among others.

Unique luminescence of non-conventional luminophores derived from space conjugation (SC) has recently attracted extensive interest. However, it is difficult to achieve highly efficient emission (especially a white light one) from SC, due to the rotational, vibrational motions of the functional groups. Herein, two simple molecules, 3,4-thiophene dicarboxylic imide (TIM) and 3,4-thiophene dicarboxylic anhydride (TAD) with a rigid and planar structure, and rich heteroatoms, are employed to respectively construct two SC systems. Both the TIM and TAD exhibit aggregation induced emission (AIE) and excitation-wavelength dependence emission in concentrated solution and crystals because of different aggregates formed through SC. Under excitation of 365 nm UV light, TIM and TAD show a warm and cold white emission with decent quantum yield up to 27%, respectively. Interestingly, TIM and TAD can produce yellow room temperature phosphorescence (RTP) at around 585 nm with the lifetime of 44 ms and 39 ms, respectively, due to the existence of heteroatoms and carbonyl groups. Compared with TAD, TIM crystals display stronger intermolecular interactions, which make its ground powder inherit the effective white emission of crystal, because the SC is not destroyed by an external force. Consequently, TIM is of huge potential in the application of white light-emitting diodes (WLEDs). Two types of single-component WLED based on TIM, driven by both UV and blue chips, give white light with CIE of (0.31, 0.39) and (0.33, 0.35), respectively. To the best of our knowledge, TIM should be the simplest single molecule white-light material applied in WLED.