Nemoto Kazuhiro, Watanabe Junpei, Yamada Hiroyuki, Sun Hong-Tao, Shirahata Naoto
Graduate School of Chemical Sciences and Engineering, Hokkaido University Sapporo 060-0814 Japan.
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) 1-1 Namiki Tsukuba 305-0044 Japan
Nanoscale Adv. 2023 Jan 17;5(3):907-915. doi: 10.1039/d2na00734g. eCollection 2023 Jan 31.
Solution-processed, cadmium-free quantum dot (QD) photodiodes are compatible with printable optoelectronics and are regarded as a potential candidate for wavelength-selective optical sensing. However, a slow response time resulting from low carrier mobility and a poor dissociation of charge carriers in the optically active layer has hampered the development of the QD photodiodes with nontoxic device constituents. Herein, we report the first InP-based photodiode with a multilayer device architecture, working in photovoltaic mode in photodiode circuits. The photodiode showed the fastest response speed with rising and falling times of = 4 ms and = 9 ms at a voltage bias of 0 V at room temperature in ambient air among the Cd-free photodiodes. The single-digit millisecond photo responses were realized by efficient transportation of the photogenerated carriers in the optically active layer resulting from coherent InP/ZnS core/shell QD structure, fast separation of electron and hole pairs at the interface between QD and Al-doped ZnO layers, and optimized conditions for uniform deposition of each thin film. The results suggested the versatility of coherent core/shell QDs as a photosensitive layer, whose structures allow various semiconductor combinations without lattice mismatch considerations, towards fast response, high on/off ratios, and spectrally tunable optical sensing.
溶液法制备的无镉量子点（QD）光电二极管与可印刷光电子器件兼容，被视为波长选择性光学传感的潜在候选者。然而，低载流子迁移率以及光活性层中电荷载流子解离不良导致的响应时间缓慢，阻碍了具有无毒器件成分的量子点光电二极管的发展。在此，我们报道了首个基于InP的具有多层器件结构的光电二极管，其在光电二极管电路中以光伏模式工作。在室温下的环境空气中，该光电二极管在0 V的电压偏置下，上升和下降时间分别为4 ms和9 ms，在无镉光电二极管中表现出最快的响应速度。通过相干InP/ZnS核壳量子点结构实现光活性层中光生载流子的高效传输、量子点与掺铝ZnO层之间界面处电子和空穴对的快速分离以及各薄膜均匀沉积的优化条件，实现了个位数毫秒的光响应。结果表明，相干核壳量子点作为光敏层具有通用性，其结构允许各种半导体组合而无需考虑晶格失配，可实现快速响应、高开关比和光谱可调谐光学传感。
