Enhanced photoluminescence quantum efficiency of Cs3Cu2I5 by modulating the superposition of exciton wavefunctions

Abstract

Although Pb-based halide perovskites exhibit excellent performance in light-emitting diode applications, their practical application is limited because Pb is a heavy metal with toxicity and poses serious risks to human health and the environment. Numerous studies have substituted Pb with other elements, such as Sn, Sb, and Bi; however, these materials cannot achieve the desired levels of emission performance and stability. Among them, Cu halide perovskites can potentially address these limitations. Cs₃Cu₂I₅ exhibits an octahedral structure and benefits from a strong Jahn–Teller effect and minimal spatial expansion of the wave function, facilitating effective exciton confinement. In this study, a new strategy to further increase the quantum efficiency and stability of Cu halide perovskites is proposed. After introducing tetrabutylammonium (TBA) into Cs₃Cu₂I₅, the crystal grain size can be modulated, enhancing the photoluminescence quantum yield up to ∼89%. Notably, this value is among the highest reported for Cs₃Cu₂I₅ perovskites. The rearrangement of TBA dopant molecules on the surface of the Cs₃Cu₂I₅ crystals contributes to improved air stability, and scintillator properties under X-ray radiation illumination are demonstrated using TBA-doped Cs₃Cu₂I₅. This study demonstrates that the proposed organic ion introduction strategy on 0D Cs₃Cu₂I₅ scintillation films can improve the luminescence properties.