基于Tamarin Prover的5G EAP-TLS协议的形式化分析

为了保证5G专用网络中移动设备的通信安全,第三代合作伙伴计划（3rd generation partnership project, 3GPP）提出了5G可扩展认证协议-传输层安全（extensible authentication protocol-transport layer security, EAP-TLS）。然而,现有的针对于5G EAP-TLS协议的研究工作较少且缺乏系统性。因此,对5G EAP-TLS协议进行详细的描述,并对该协议进行全面的形式化建模。对5G规范中涉及的所有协议实体以及证书分发机制进行建模,同时从5G规约中提取并建模了与5G EAPTLS协议相关的安全目标。提出证据搜索策略引导符号分析工具Tamarin Prover进行自动化证据搜索,解决了Tamarin Prover在验证复杂模型时验证过程无法终止的问题,实现了5G EAP-TLS安全目标的自动化验证。通过分析验证结果,发现了5G EAP-TLS协议能够满足机密性目标,但难以满足一些认证性目标,同时,揭示了协议存在拒绝服务（denial of service,DoS）攻击和用户通信数据泄露的隐患。针对...     

Low-dimensional phases engineering for improving the emission efficiency and stability of quasi-2D perovskite films

The two-dimensional (2D) Ruddlesden-Popper-type perovskites, possessing tunable bandgap, narrow light emission, strong quantum confinement effect, as well as a simple preparation method, are identified as a new generation of candidate materials for efficient light-emitting diodes. However, the preparation of high-quality quasi-2D perovskite films is still a challenge currently, such as the severe mixing of phases and a high density of defects within the films, impeding the further promotion of device performance. Here, we prepared the quasi-2D PEA₂MA_n-1Pb_nBr_3n+1 perovskite films by a modified spin-coating method, and the phases with large bandgap were effectively suppressed by the vacuum evaporation treatment. We systematically investigated the optical properties and stability of the optimized films, and the photoluminescence (PL) quantum yield of the treated films was enhanced from 23% to 45%. We also studied the emission mechanisms by temperature-dependent PL spectra. Moreover, the stability of films against moisture, ultraviolet light, and heat was also greatly improved.     

混合反溶剂法制备CsCu2I3纳米晶薄膜及其发光器件应用

近年来，新兴的三元铜基卤化物(CsCu₂I₃)材料由于具有高荧光量子产率、环保无毒、环境稳定、成本低廉等诸多优点，在环保型发光二极管(LED)中的应用备受瞩目。然而，由于难以控制的结晶动力学，制备高质量的CsCu₂I₃发光层薄膜仍是一个巨大的挑战，这限制了LED器件性能的进一步提升。本文通过使用甲苯与甲醇混合溶剂作为反溶剂来增强反溶剂的钉扎效应，增加CsCu₂I₃晶体的成核密度，降低薄膜的晶粒尺寸，进而形成了光滑、致密的CsCu₂I₃纳米晶薄膜。此外，混合反溶剂策略可以有效增强辐射复合效率，显著提高CsCu₂I₃薄膜的发光性能，相比对照样品(只使用甲苯)，混合反溶剂法所制备薄膜的荧光量子产率(PLQY)增加了1.5倍，激子束缚能从～201.6 meV提高至～234.5 meV。最终，相比对照器件，基于混合反溶剂策略的CsCu₂I₃