Electrospun Janus nanofibers for white-light emission through efficient spatial isolation to control two-step energy transfer

White-light-emitting materials are an important component for realizing full-color OLED devices. However, it is still a challenge to achieve white-light emission from one single fluorescent dye, as the essential requirement of the emission spectrum is that it should be sufficiently broad to cover the entire visible-light region. Controlling the energy transfer between two or three fluorescent dyes is a feasible approach for achieving white-light emission, and this has attracted widespread attention from many researchers. In this study, a white-light-emitting Janus nanofiber film was fabricated using a side-by-side electrospinning method. RGB fluorescent molecules were used to form a donor–acceptor system, where the red and blue fluorescent molecules were located on the PAN-side of the nanofiber, and the green fluorescent molecules were located on the PVP-side of the nanofiber. The Janus structure enabled an efficient spatial separation of the RGB fluorescent molecules within the nanofiber while rationally regulating the two-step energy transfer effect between the RGB fluorescent molecules, resulting in the emission of uniform white light from every individual microscopic-sized nanofiber. Such nanofiber films have great potential for use in next-generation flexible display applications due to their excellent performance and micro scale.