Mixed-dimensional systems host interesting phenomena that involve electron and ion transport along or across the interface, with promising applications in optoelectronic and electrochemical devices. Herein, a heterosystem consisting of a graphene monolayer with a colloidal Ag₂S nanocrystal film atop, in which both ions and electrons are involved in photoelectrical effects, is studied. An investigation of the transport at the interface in different configurations by using a phototransistor configuration with graphene as a charge-transport layer and semiconductor nanocrystals as a light-sensitive layer is performed. The key feature of charge transfer is investigated as a function of gate voltage, frequency, and incident light power. A simple analytical model of the photoresponse is developed, to gain information on the device operation, revealing that the nanocrystals transfer electrons to graphene in the dark, but the opposite process occurs upon illumination. A frequency-dependence analysis suggests a fractal interface between the two materials. This interface can be modified using solid-state electrochemical reactions, leading to the formation of metallic Ag particles, which affect the graphene properties by additional doping, while keeping the photoresponse. Overall, these results provide analytical tools and guidelines for the evaluation of coupled electron/ion transport in hybrid systems.

中文翻译：

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在石墨烯/Ag2S 界面模拟光电检测

混合维系统包含有趣的现象，涉及电子和离子沿界面或跨界面传输，在光电和电化学设备中具有广阔的应用前景。在此，由石墨烯单层和胶体 Ag ₂组成的异质系统研究了顶部的 S 纳米晶体薄膜，其中离子和电子都参与光电效应。通过使用石墨烯作为电荷传输层和半导体纳米晶体作为光敏层的光电晶体管配置，对不同配置的界面处的传输进行了研究。电荷转移的关键特征被研究为栅极电压、频率和入射光功率的函数。开发了一个简单的光响应分析模型，以获取有关器件操作的信息，揭示纳米晶体在黑暗中将电子转移到石墨烯，但在光照时会发生相反的过程。频率相关性分析表明两种材料之间存在分形界面。该界面可以使用固态电化学反应进行修改，导致金属银颗粒的形成，通过额外的掺杂影响石墨烯的特性，同时保持光响应。总体而言，这些结果为评估混合系统中的耦合电子/离子传输提供了分析工具和指南。