Highly efficiency blue emissive from Bi3+ ions in zero-dimensional organic bismuth halide for white LED applications

Zero-dimensional organic-inorganic metal halides (OMHs) attract increasing interest in the fabrication of light-emitting diodes because of their broad emission band and high photoluminescence quantum yield. Thus, almost all OMHs showed green and yellow emissions, while blue was rarely reported. The luminescence mechanism of OMHs was attributed to the self-trapped excitons (STEs), no matter the similar performances between STEs and translations from energy levels of ns2 ions (Sb3+, Bi3+, and Te4+ ions). In this work, zero-dimensional organic tetraphenylphosphonium bismuth chloride TPP2BiCl5 (C48H40P2BiCl5, abbreviated as TBC, TPP=tetraphenylphosphonium.) was synthesized via the antisolvent method The obtained TBC showed the highest efficiency (58%) in blue light emission at 480 nm. While most of the OMHs function according to the STE mechanism, the emission of TBC was confirmed to originate from the 3P1-1S0 transition of Bi3+ ions. The white light-emitting diodes (WLEDs) with a color rendering index of 81 were fabricated by using a near-ultraviolet (NUV) chip, blue emitting single crystal TBC, green-emitting single crystal TPP2MnCl4 (C48H40P2MnCl4, abbreviated as TMC), and red-emitting single crystal TPP2SbCl5 (C48H40P2SbCl5, abbreviated as TSC). Moreover, the single-component white emission was achieved by doping Mn2+ and Sb3+ ions into the lattice of TBC. This work demonstrates the different emission mechanism of ns2 ions based OMHs, and the great potential of bismuth-based OMHs in the applications of WLEDs.