Large-scale room-temperature synthesis and optical properties of perovskite-related Cs4PbBr6 fluorophores

Abstract

Currently, metal–halide perovskite semiconductors have attracted enormous attention for their excellent optical performance. However, challenging issues, such as the ability to perform large-scale synthesis as well as the thermal/moisture stability, limit their practical applications. Herein, we developed an inhomogeneous interface reaction strategy in a liquid–liquid immiscible two-phase system to realize the large-scale room temperature synthesis of novel perovskite-related Cs₄PbBr₆ semiconductors. Although the sizes were on the micrometer scale, the Cs₄PbBr₆ products exhibited bright green luminescence with a narrow line-width originating from exciton recombination confined in PbBr₆⁴⁻ octahedra, and the photoluminescence quantum yields reached 40–45% owing to a large exciton binding energy of 222 meV. Furthermore, temperature cycling experiments demonstrated their excellent thermal stability with repeatable and reversible luminescence, and moisture-resistance experiments showed ∼65% of quantum yield loss after exposure to air for one month. Finally, a prototype white light-emitting diode device with a low correlated color temperature of 3675 K and a high color rendering index of 83 was constructed using green emissive Cs₄PbBr₆ and red emissive Eu²⁺:CaAlSiN₃ phosphors, certainly indicating its promising applications in the optoelectronics field.