Shang Ju Y, Giancaspro Mariangela, Grandolfo Adriana, Lakho Rafique A, Fanizza Elisabetta, Patel Suraj K, Bianco Giuseppe Valerio, Striccoli Marinella, Ingrosso Chiara, Vazquez-Mena Oscar, Curri M Lucia
Program of Materials Science, University of California San Diego, La Jolla, CA 92093, USA.
Aiiso Yufeng Li Family Department of Chemical and Nano Engineering, Center for Memory and Recording Research, University of California San Diego, 9500 Gilman Drive #0401, La Jolla, CA 92093, USA.
Molecules. 2024 Dec 27;30(1):67. doi: 10.3390/molecules30010067.
Optoelectronic devices combining single-layer graphene (SLG) and colloidal semiconducting nanocrystal (NC) heterojunctions have recently gained significant attention as efficient hybrid photodetectors. While most research has concentrated on systems using heavy metal-based semiconductor NCs, there is a need for further exploration of environmentally friendly nanomaterials, such as CuS. Chemical ligands play a crucial role in these hybrid photodetectors, as they enable charge transfer between the NCs and SLG. This study investigates the photoresponse of an SLG/CuS NCs heterojunction, comparing the effect of two short molecules-tetrabutylammonium iodide (TBAI) and 3,4-dimethylbenzenethiol (DMBT)-as surface ligands on the resulting structures. We have analysed charge transfer at the heterojunctions between SLG and the CuS NCs before and after modification with TBAI and DMBT using Raman spectroscopy and transconductance measurements under thermal equilibrium. The photoresponse of two hybrid devices based on three layers of Cu₋S NCs, deposited in one case on SLG/CuS/TBAI ("TBAI-only" device) and in the other on SLG/CuS/DMBT ("DMBT + TBAI" device), with a TBAI treatment applied, for both, after each layer deposition, has been evaluated under 450 nm laser diode illumination. The results indicate that the TBAI-only device exhibited a significant increase in photocurrent (4 μA), with high responsivity (40 mA/W) and fast response times (<1 s), while the DMBT + TBAI device had lower photocurrent (0.2 μA) and responsivity (2.4 μA), despite similar response speeds. The difference is attributed to DMBT's π-π interactions with SLG, which enhances electronic coupling but reduces SLG's mobility and responsivity.
结合单层石墨烯（SLG）和胶体半导体纳米晶体（NC）异质结的光电器件，作为高效的混合光电探测器最近受到了广泛关注。虽然大多数研究集中在使用重金属基半导体纳米晶体的系统上，但仍需要进一步探索环境友好型纳米材料，如硫化铜（CuS）。化学配体在这些混合光电探测器中起着至关重要的作用，因为它们能够实现纳米晶体与单层石墨烯之间的电荷转移。本研究调查了单层石墨烯/硫化铜纳米晶体异质结的光响应，比较了两种短分子——四丁基碘化铵（TBAI）和3,4 - 二甲基苯硫酚（DMBT）作为表面配体对所得结构的影响。我们使用拉曼光谱和热平衡下的跨导测量，分析了用TBAI和DMBT修饰前后，单层石墨烯与硫化铜纳米晶体之间异质结处的电荷转移。在450纳米激光二极管照明下，评估了基于三层硫化铜纳米晶体的两种混合器件的光响应，一种情况是沉积在单层石墨烯/硫化铜/TBAI（“仅TBAI”器件）上，另一种是沉积在单层石墨烯/硫化铜/DMBT（“DMBT + TBAI”器件）上，且在每层沉积后都对两者进行了TBAI处理。结果表明，仅TBAI器件的光电流显著增加（4 μA），具有高响应度（40 mA/W）和快速响应时间（<1 s），而DMBT + TBAI器件的光电流较低（0.2 μA）且响应度较低（2.4 μA），尽管响应速度相似。这种差异归因于DMBT与单层石墨烯的π - π相互作用，它增强了电子耦合，但降低了单层石墨烯的迁移率和响应度。
