柔性0D-2D混合维度异质结光电探测器阵列研究

Flexible photodetectors are the key components of many wearable products in personal healthcare, military security and commercial digital fields. Thanks to large carrier mobility and surface-to-volume ratio, substantial effort has been devoted to two-dimensional (2D) materials for flexible optoelectronics. Although 2D material photodetectors have demonstrated µs-level photoresponse, they normally exhibit small photogain, resulted from atomically thin thickness induced limited optical absorption. Another major challenge is performing large-area synthesis for 2D materials with high crystal quality. In comparison, perovskite quantum dots (QDs) not only possess large optical absorptance and tunable bandgaps, enabling them qualified to be absorption layers, but also they can be large-scale prepared through efficient chemical solution deposition techniques. Nevertheless, perovskite QDs based photodetectors generally show slow photoresponse rate, owing to their limited electrical conductivity. In this project, it is proposed to combine the doped perovskite QDs and the inch-sized monolayer 2D materials to create large-scale heterostructures on flexible substrates, in which the two materials can serve as optical absorption layers and carrier transport tunnels, respectively. Afterwards, the photogating effect assisted phototransistor arrays based on the perovskite QDs/2D material heterostructures will be fabricated, which are expected to show high performance, spatial uniformity, mechanical flexibility and air stability. Based on the obtained heterostructures with mixed-dimensionality and the flexible phototransistor arrays, the studies focused on carrier transport mechanisms of heterojunction interface and optimizing device fabrication techniques will be carried out comprehensively.

柔性光电探测器是医疗健康、军事安全、民用数码领域的可穿戴设备的核心部件。二维材料得益于高载流子迁移率和大比表面积的特点，正在柔性光电子领域受到广泛关注。但受限于原子级厚度引起的吸光能力不足，基于二维材料的光电探测器尽管能够达到微秒级的光响应，但往往表现出较低的光增益，且大面积制备高质量二维材料也是面临的一大挑战。相较之下，钙钛矿量子点不仅具有高光吸收系数和可调带隙，能够作为优秀的光吸收层材料，且能够通过高效的化学溶液法进行大规模制备。但受限于导电能力不足，基于钙钛矿量子点的光电探测器通常表现出较慢的光响应。本项目拟利用掺杂的钙钛矿量子点作为光吸收层和英寸级二维材料作为沟道层，在柔性衬底上构筑大面积0D-2D混合维度异质结，并以此制备兼顾高性能、均衡性、柔性和稳定性的光栅型钙钛矿量子点/二维材料异质结光电晶体管阵列，研究混合维度异质结界面载流子输运机理，并掌握柔性探测器平面阵列的制备工艺。

低维度半导体材料及其混合维度异质结具有高载流子迁移率、带隙可调、量子限域效应、柔性等特点，在柔性电子、新一代光电探测、生物电子等领域具有广阔的应用前景。本项目围绕零维（0D）钙钛矿量子点、二维（2D）材料和0D-2D混合维度异质结开展研究，分别在刚性衬底Si/SiO2和柔性衬底PET上制备得到光电探测器。本项目先后开展了离子掺杂调控钙钛矿量子点的光电特性、大面积二维材料薄膜的制备与光电探测器制造、混合维度异质结的制备、表征与器件制造、基于柔性衬底的器件制备与光电性能的研究工作，阐明了钙钛矿量子点的离子掺杂和二维材料的表面钝化对于陷阱电荷输运和光电记忆特性的影响机理，结合系统的实验表征结果探索了混合维度异质结界面的光生载流子输运的物理机制，丰富现有的异质结和载流子输运理论。基于大面积2D二硫化钼的光电探测器，实现了在405 nm激光光照下可用于光照时长编码和模拟压力诱导下的完整记忆行为（包括记忆编码、存储和再检索）；在可见光激发下持续光电导 (PPC) 效应使光电探测器能够处理时序信息，而异源性突触启发的结构使基于该光电探测器的视觉系统能够处理空间模式。基于离子掺杂的钙钛矿量子点的柔性光电探测器在自供能的工作模式下，其开关比可达~1e4，探测率为~1e11 Jones。通过混合维度异质结的制备与表征，探索了异质结的制备工艺，开展了系统的材料表征工作鉴定异质结界面的质量、研究界面处的物理现象和电荷的输运机制。成果方面，累计发表SCI论文2篇，培养毕业博士研究生2人，培养在读硕士研究生2人，开展国际会议特邀报告1次。