van der Waals Heterostructures for Next-generation Hot Carrier Photovoltaics

用于下一代热载流子光伏的范德华异质结构

• 批准号: EP/Y028287/1
• 负责人: Manish Chhowalla
• 金额: $ 25.55万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FY028287%2F1
• 关键词: van; der; Waals; Heterostructures; Next

In contrast to the bulk semiconductors, spatially confined van der Waals (vdWs) layered materials possess strong Coulomb interaction, high exciton binding energy, reduced charge screening and low electron-phonon coupling, leading to a slower hot carrier (HC) cooling. Efficient direct interlayer HC transfer has been observed in vdWs heterostructures without phonon emission due to momentum conservation at K-point. In a graphene-based vdWs heterostructure, considerably high optical absorbance leads to the enhanced photocarrier density, which invokes the hot-phonon bottleneck effect, leading to prolonged HC cooling in graphene. The aforementioned advantages of suitably designed vdWs heterostructures are certainly advantageous for fabrication of efficient HC solar cells (HCSCs), restricting the ultrafast thermalization of HCs and exceeding the Shockley-Queisser limit. In this work, low bandgap (~1-1.5 eV) transition metal dichalcogenides (TMDs) of various layer thicknesses (transition metal: Mo, W; chalcogenide: S, Se, Te) with high optical absorbance will be grown and integrated with graphene having ultraclean interface for the fabrication of HCSCs. HC dynamics including the type of HC, temperature, HC lifetime, and carrier multiplication will be investigated by time- and angle-resolved photoemission spectroscopy to probe the solar light driven HC photovoltaic characteristics. Optimized graphene/TMD vdWs heterostructures will be integrated with proper energy selective contacts (ESCs) and metal electrodes with appropriate work functions for the efficient HCs collection in HCSCs. The thickness of the ESCs will be tuned for the maximum HCs tunneling to the metal electrodes through the ESCs. Demonstration of HC-driven photovoltaics will be carried out by current-voltage (I-V) measurements with various energetic laser illuminations. Large area HCSCs will be realized with wafer-scale growth of vdWs materials and I-V measurements under solar simulator (1-SUN AM1.5).

与体半导体相比，空间受限的范德华（vdW）层状材料具有强库仑相互作用、高激子结合能、减少的电荷屏蔽和低电子声子耦合，导致热载流子（HC）冷却速度较慢。由于 K 点动量守恒，在 vdWs 异质结构中观察到有效的直接层间 HC 转移，而没有声子发射。在基于石墨烯的 vdWs 异质结构中，相当高的光吸收率导致光载流子密度增强，从而引发热声子瓶颈效应，导致石墨烯中的 HC 冷却时间延长。适当设计的 vdW 异质结构的上述优点对于高效 HC 太阳能电池 (HCSC) 的制造无疑是有利的，限制了 HC 的超快热化并超过 Shockley-Queisser 极限。在这项工作中，具有高光吸收率的各种层厚度的低带隙（~1-1.5 eV）过渡金属二硫属化物（TMD）（过渡金属：Mo、W；硫属化物：S、Se、Te）将生长并与石墨烯集成具有用于制造 HCSC 的超净接口。 HC 动力学，包括 HC 类型、温度、HC 寿命和载流子倍增，将通过时间和角度分辨光电子能谱进行研究，以探测太阳光驱动的 HC 光伏特性。优化的石墨烯/TMD vdWs 异质结构将与适当的能量选择性接触 (ESC) 和具有适当功函数的金属电极集成，以便在 HCSC 中高效收集 HC。 ESC 的厚度将根据通过 ESC 隧道到金属电极的最大 HC 进行调整。 HC 驱动光伏发电的演示将通过各种高能激光照明的电流-电压 (I-V) 测量来进行。大面积 HCSC 将通过 vdWs 材料的晶圆级生长和太阳模拟器 (1-SUN AM1.5) 下的 I-V 测量来实现。