Department of Materials Science and Engineering, KAIST Institute for the Nanocentury (KINC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea.
Sci Adv. 2023 Feb 17;9(7):eade2585. doi: 10.1126/sciadv.ade2585.
Graphene quantum dots (GQDs) are nanosized graphene derivatives with unique photoluminescence (PL) properties that have advantages in optoelectronic applications due to their stable blue light emission. However, aggregation-caused quenching (ACQ) of GQDs limits the practical applications on light-emitting diodes. Here, we suppress the ACQ phenomena of GQDs by reducing the size and converting GQDs into aggregation-induced emission (AIE)-active materials. As the size of GQDs is reduced from 5 to 1 nm, their solid-state PL quantum yields (PLQYs) are improved from 0.5 to 2.5%, preventing ACQ. Two different rotor molecules, benzylamine (BA) and 4,4'-(1,2-diphenylethene-1,2-diyl)diphenol (TPE-DOH), are selectively functionalized by substituting carboxylic acid and carbonyl functional groups. All functionalized GQDs show AIE behaviors with significantly enhanced solid-state PLQYs, up to 16.8%. Afterglow measurements and theoretical calculations reveal that selective functionalization hinders inter- and intramolecular charge transfer, which enhances the fluorescence rate of GQDs and corresponding PLQY.
石墨烯量子点（GQDs）是具有独特光致发光（PL）性能的纳米级石墨烯衍生物，由于其稳定的蓝光发射，在光电应用中具有优势。然而，GQDs 的聚集诱导猝灭（ACQ）限制了其在发光二极管中的实际应用。在这里，我们通过减小尺寸并将 GQDs 转化为聚集诱导发射（AIE）活性材料来抑制 GQDs 的 ACQ 现象。当 GQDs 的尺寸从 5nm 减小到 1nm 时，其固态 PL 量子产率（PLQY）从 0.5%提高到 2.5%，从而防止了 ACQ。两种不同的转子分子，苄胺（BA）和 4,4'-(1,2-二苯乙烯-1,2-二基)二酚（TPE-DOH），通过取代羧酸和羰基官能团被选择性功能化。所有功能化的 GQDs 都表现出 AIE 行为，固态 PLQY 显著增强，高达 16.8%。余辉测量和理论计算表明，选择性功能化阻碍了分子内和分子间的电荷转移，从而提高了 GQDs 的荧光速率和相应的 PLQY。
