In recent years, there has been a concerted effort in developing narrow band gap semiconductors that exhibit excellent physical properties and optoelectronic performance, as well as enhanced solution processability and structural stability. Herein, we report a new series of copper(I)iodide-based ionic hybrid semiconductors with narrow band gaps (∼1.5–1.8 eV). These compounds are systematically designed by using pyrazine derivatives as cationic ligands and various 1D-Cu_mI_n chains as anionic inorganic motifs to form one-dimensional (1D) structures. They demonstrate high optical absorption coefficients, decent electrical conductivity, excellent air/moisture/thermal stability, and superb solution processability, enabling the fabrication of high-quality thin films via simple solution processes. Additionally, we have carried out a comprehensive photoelectron spectroscopic study on highly orientated thin film samples of selected hybrid compounds to experimentally verify, for the first time, that the photoexcitation process in such materials involves an anion-to-cation through-space charge transfer (TSCT), consistent with the calculated electronic structures. Overall, these narrow band gap CuI-based hybrid semiconductors define a new subclass of low-cost, highly stable, and efficient light-absorbing materials promising for applications in optoelectronics.

中文翻译：

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窄带隙混合碘化铜：用于光电应用的设计材料


近年来，人们齐心协力开发窄禁带半导体，这些半导体表现出优异的物理性能和光电性能，以及增强的溶液加工性和结构稳定性。在此，我们报道了一系列新的基于碘化铜的离子混合半导体，具有窄带隙 （∼1.5–1.8 eV）。这些化合物是通过使用吡嗪衍生物作为阳离子配体和各种 1D-Cu_mI_n 链作为阴离子无机基序来系统设计的，以形成一维 （1D） 结构。它们具有高光吸收系数、良好的导电性、出色的空气/水分/热稳定性和卓越的固溶加工性能，能够通过简单的固溶工艺制造高质量的薄膜。此外，我们还对选定杂化化合物的高度定向薄膜样品进行了全面的光电子能谱研究，以首次实验验证此类材料中的光激发过程涉及阴离子到阳离子通过空间电荷转移 （TSCT），这与计算的电子结构一致。总体而言，这些基于窄带隙 CuI 的混合半导体定义了一个低成本、高度稳定和高效的光吸收材料的新子类，有望在光电子学中应用。