Circularly Polarized Fluorescence Energy Transfer for Constructing Multicolor Circularly Polarized Luminescence Films with Controllable Handedness

Utilizing achiral fluorophores to fabricate circularly polarized luminescence (CPL) materials is of significant importance in both fundamental research and practical applications; chirality transfer has become an indispensable process in routine efforts reported so far. However, this may restrict or even become a bottleneck in further advancing CPL materials starting from achiral fluorophores. Inspired by biological light-harvesting architectural systems, we attempt to establish a new strategy, i.e., circularly polarized fluorescence energy transfer (CPF-ET) to explore multicolor CPL films in the absence of chirality transfer. CPL has been successfully realized through both radiative energy transfer and nonradiative energy transfer. The material systems consist of chiral fluorescent helical polyacetylene working as a circularly fluorescence polarized energy donor and achiral fluorophores as an energy acceptor. Achiral acceptors absorb circularly polarized fluorescence energy from the donor and hence emit the corresponding CPL; accordingly, chirality transfer is no longer an indispensable condition, and the sense of the CPL emission of the achiral fluorophores is controlled by the chiral fluorescent polymer. Moreover, multicolor CPL films can be simply prepared by employing varying achiral fluorophores. This work provides a facile and versatile platform for achieving CPL by taking advantage of achiral fluorophores.