近日，郑州大学的史志锋&马壮壮及其研究小组与北京理工大学的李颖等人合作并取得一项新进展。经过不懈努力，他们同时在Cs₂CoCl₄单晶中实现负光导响应和挥发性电阻开关，以实现人工光电突触。相关研究成果已于2024年12月2日在国际知名学术期刊《光：科学与应用》上发表。

据悉，负光导性（NPC）相关器件的开发对于众多应用领域具有重要意义，如光电检测、神经形态计算和光电突触。

本文报道了一种基于新型铯钴氯（Cs₂CoCl₄）单晶的光电器件中不同寻常但颇有趣味的NPC现象，该器件同时具备挥发性阻变（RS）存储行为。联合实验与理论表征揭示，NPC行为源自Cs₂CoCl₄的本征空位缺陷，这些缺陷能够捕获光生电荷载流子，并产生一个与外部电场方向相反的内部电场。

这种NPC效应实现了异常的光检测性能，表现为光照下电导率的降低。此外，该器件还实现了2.7×10¹²琼斯的高特异性探测率和265至780纳米的宽波段NPC检测波长。除了NPC响应外，所制备的器件还展现出在5×10⁴Vm^-1的极低电场下的挥发性RS性能。

通过结合RS的电脉冲增强特性和NPC的光脉冲抑制特性，成功演示了一个人工光电器件突触，并基于人工神经网络算法的模拟实现了手写数字图像的识别应用。这些开创性发现有望为金属卤化物，在存储技术和人工智能领域的实际应用做出重要贡献。

附：英文原文

Title: Simultaneous achieving negative photoconductivity response and volatile resistive switching in Cs₂CoCl₄ single crystals towards artificial optoelectronic synapse

Author: Jiang, Huifang, Ji, Huifang, Ma, Zhuangzhuang, Yang, Dongwen, Ma, Jingli, Zhang, Mengyao, Li, Xu, Wang, Meng, Li, Ying, Chen, Xu, Wu, Di, Li, Xinjian, Shan, Chongxin, Shi, Zhifeng

Issue&Volume: 2024-12-02

Abstract: The development of negative photoconductivity (NPC)-related devices is of great significance for numerous applications, such as optoelectronic detection, neuromorphic computing, and optoelectronic synapses. Here, an unusual but interesting NPC phenomenon in the novel cesium cobalt chlorine (Cs₂CoCl₄) single crystal-based optoelectronic devices is reported, which simultaneously possess volatile resistive switching (RS) memory behavior. Joint experimenttheory characterizations reveal that the NPC behavior is derived from the intrinsic vacancy defects of Cs₂CoCl₄, which could trap photogenerated charge carriers and produce an internal electric field opposite to the applied electric field. Such NPC effect enables an abnormal photodetection performance with a decrease in electrical conductivity to illumination. Also, a large specific detectivity of 2.7×10¹² Jones and broadband NPC detection wavelength from 265 to 780nm were achieved. In addition to the NPC response, the resulting devices demonstrate a volatile RS performance with a record-low electric field of 5×10⁴Vm^-1. By integrating the characteristics of electric-pulse enhancement from RS and light-pulse depression from NPC, an artificial optoelectronic synapse was successfully demonstrated, and based on the simulation of artificial neural network algorithm, the recognition application of handwritten digital images was realized. These pioneer findings are anticipated to contribute significantly to the practical advancement of metal halides in the fields of in-memory technologies and artificial intelligence.

DOI: 10.1038/s41377-024-01642-8

Source: https://www.nature.com/articles/s41377-024-01642-8