Novel near-unity 0D organic-inorganic copper-based halide TEA2Cu2Br4 for high-efficiency and stable ultraviolet photodetectors

Abstract

Low-dimensional copper-based halides have attracted significant attention in the development of ultraviolet photodetectors (PDs) owing to their non-toxic nature, wide band gap, strong light absorption, and long carrier diffusion length. However, the performance of these devices has been constrained by the material's intrinsically low photoluminescence quantum yields (PLQYs), uneven grain size, and agglomeration. In this study, we synthesized a novel 0D copper-based halide [N(C₂H₅)₄]₂Cu₂Br₄ (TEA₂Cu₂Br₄) using a simple solution-based method and demonstrated high-performance ultraviolet PDs based on this material. TEA₂Cu₂Br₄ exhibits a unique dendritic structure with exceptionally long crystals and an outstanding PLQY approaching unity, reflecting a very low trap density and excellent stability. Moreover, the PD device based on TEA₂Cu₂Br₄ crystals achieved remarkably impressive responsivity (R) of 5.07 A/W, high detectivity (D∗) of 7.04 × 10¹² Jones, and fast response rates (τ_r of 11.52 ms and τ_f of 11.22 ms), demonstrating superior detection capabilities. Notably, the device maintains 90 % of its photocurrent output after 3000 h of aging without encapsulation, highlighting its exceptional stability. This work indicates TEA₂Cu₂Br₄ as an ideal active material for the development of high-performance and stable PDs, offering a promising pathway towards environmentally friendly optoelectronic devices.