离子工程调控天然二维黑云母的绝缘体-半导体转变

中文摘要 AI 辅助

天然层状硅酸盐是一类储量丰富但尚未被充分开发的二维材料，但其绝缘特性限制了功能应用。本研究展示了一种化学策略，通过可控NaOH处理将液相剥离的黑云母纳米片转化为可调控的二维半导体。该绝缘体-半导体转变源于Na掺入、缺陷产生和局部结构重构，同时基本保留层状框架。结构与化学分析揭示了晶格畸变、层间重组、羟基化及部分Na+-K+交换，明确了电子结构重构的起源。该转变拓宽了光学响应，使约221 nm的吸收峰移至约280 nm和975 nm，光学带隙从约5.2 eV降至3.2-3.5 eV，并引入约1.12-1.17 eV的低能跃迁。电学测量显示非线性输运，电流接近10 μA，表明存在激活型载流子传导。超快瞬态吸收揭示了显著的激发态吸收，载流子冷却时间为0.16-0.38 ps，随后是与陷阱介导复合相关的快（35-60 ps）和长寿命（336-491 ps）弛豫。通量依赖动力学显示，高载流子密度下存在热声子瓶颈。结合密度泛函理论计算，这些结果证实化学缺陷与离子工程是将天然丰富层状矿物转化为电子可调控二维材料的有效途径，适用于新兴光电子和超快光子技术。

英文摘要

Naturally occurring layered silicates offer an abundant yet unexplored class of 2D materials, but their insulating nature limits their functional utility. Here, we demonstrate a chemical strategy that transforms liquid-phase-exfoliated biotite nanosheets into a tunable 2D semiconductor through controlled NaOH treatment. The resulting insulator-to-semiconductor transition originates from Na incorporation, defect generation, and local structural reconstruction while largely preserving the layered framework. Structural and chemical analyses reveal lattice distortion, interlayer reorganization, hydroxylation, and partial Na+-K+ exchange, establishing the origin of the electronic restructuring. This transformation broadens the optical response, shifting the approximately 221 nm absorption toward approximately 280 and 975 nm, reducing the optical bandgap from approximately 5.2 to 3.2-3.5 eV, and introducing low-energy transitions at approximately 1.12-1.17 eV. Electrical measurements reveal nonlinear transport with currents reaching close to 10 microA, demonstrating activated carrier conduction. Ultrafast transient absorption reveals pronounced excited-state absorption, with carrier cooling (0.16-0.38 ps) followed by fast (35-60 ps) and long-lived (336-491 ps) relaxation associated with trap-mediated recombination. Fluence-dependent dynamics reveal a hot-phonon bottleneck at elevated carrier densities. Together with density functional theory calculations, these results establish chemical defect and ion engineering as a powerful route for converting naturally abundant layered minerals into electronically tunable 2D materials for emerging optoelectronic and ultrafast photonic technologies.

发表机构

• Indian Institute of Technology Kharagpur（印度理工学院卡拉格普尔分校）
• State University of Campinas（坎皮纳斯州立大学）
• Rice University（莱斯大学）
• University of Brasília（巴西利亚大学）

机构由 AI 辅助整理，请以论文原文为准。