De novo design of single white-emitting polymers based on one chromophore with multi-excited states

Abstract

Single white-emitting polymers (SWPs) based on multi-chromophores with different colors are believed to show a great potential in solution-processed white light-emitting diodes (WOLEDs). However, they suffer from the extremely low loadings (one ten thousandth to one thousandth) for long-wavelength chromophores when incorporated into SWPs. To solve this bottleneck, we newly propose a one chromophore with multi-excited states strategy for the de novo design of SWPs. By adopting acridine as the donor (D), dibenzothiophene-S,S-dioxide as the acceptor (A) and oxygen as the linker between D and A to constitute the central chromophore fragment, P(DMPAc-O-DBTDO) is successfully developed to possess not only fluorescence and thermally-activated delayed fluorescence from the lowest singlet state (S1), but also room-temperature phosphorescence from the lowest triplet state (T1). As a consequence, a very broad electroluminescence that covers the whole visible region from 400 to 750 nm is realized, leading to an efficient and stable white light with a peak power efficiency of 7.5 lm W−1 (9.5 cd A-1, 3.7%). Meanwhile, the Commission Internationale de l’Eclairage (CIE) coordinates and correlated color temperature (CCT) could be well tuned in a wide doping concentration window (15–100%) for different illumination requirements.