Park Gyurim, Kim Hyungchae, Yang Hoichang, Park Kyung Ryoul, Song Inho, Oh Joon Hak, Kim Changsoon, You Youngmin
Division of Chemical Engineering and Materials Science , Ewha Womans University , Seoul 03760 , The Republic of Korea . Email:
Graduate School of Convergence Science and Technology , Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , The Republic of Korea.
Chem Sci. 2018 Nov 29;10(5):1294-1301. doi: 10.1039/c8sc04509g. eCollection 2019 Feb 7.
Molecules capable of producing zero-field circularly polarized phosphorescence (CPP) are highly valuable for chiroptoelectronic applications that rely on triplet exciton. However, the paucity of tractable molecular design rules for obtaining CPP emission has inhibited full utilization. We report amplification of CPP by the formation of helical co-assemblies consisting of achiral square planar cycloplatinated complexes and small fractions of homochiral cycloplatinated complexes. The latter has a unique Pfeiffer effect during the formation of superhelical co-assemblies, enabling versatile chiroptical control. Large dissymmetry factors in electronic absorption ( , 0.020) and phosphorescence emission ( , 0.064) are observed from the co-assemblies. These values are two orders of magnitude improved relative to those of individual molecules. In addition, photoluminescence quantum yields (PLQY) also increase by a factor of ten. Our structural, photophysical, and quantum chemical investigations reveal that the chiroptical amplification is attributable to utilization of both the magnetically allowed electronic transition and asymmetric coupling of excitons. The strategy overcomes the trade-off between and PLQY which has frequently been found for previous molecular emitters of circularly polarized luminescence. It is anticipated that our study will provide new insight into the future research for the exploitation of the full potential of CPP.
能够产生零场圆偏振磷光（CPP）的分子对于依赖三重态激子的手性光电器件应用具有极高价值。然而，缺乏用于获得CPP发射的易于处理的分子设计规则阻碍了其充分利用。我们报道了通过由非手性平面正方形环金属化配合物和少量同手性环金属化配合物形成螺旋共组装体来放大CPP。后者在超螺旋共组装体形成过程中具有独特的普费弗效应，实现了多功能手性光学控制。从共组装体中观察到电子吸收（，0.020）和磷光发射（，0.064）中的大不对称因子。这些值相对于单个分子的值提高了两个数量级。此外，光致发光量子产率（PLQY）也提高了十倍。我们的结构、光物理和量子化学研究表明，手性光学放大归因于磁允许电子跃迁和激子的不对称耦合的利用。该策略克服了先前圆偏振发光分子发射体中经常发现的在和PLQY之间的权衡。预计我们的研究将为未来充分开发CPP潜力的研究提供新的见解。
