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).

与散装半导体相反，空间上限制的范德华（VDWS）分层材料具有较强的库仑相互作用，高激子结合能，降低电荷筛选和低电子波耦合，从而导致较慢的热载体（HC）冷却。由于K点处的动量保护，在没有声子发射的VDWS异质结构中观察到有效的直接层间HC转移。在基于石墨烯的VDW异质结构中，光学吸光度相当高导致增强的光载体密度，从而调用了热孔孔瓶颈效应，从而导致石墨烯中的HC冷却延长。适当设计的VDW异质结构的上述优势无疑对于制造有效的HC太阳能电池（HCSC），限制了HCS的超快热化并超过了冲击式标题极限。在这项工作中，各种层厚度（过渡金属：MO，W; Chalcogenide：S，SE，TE）的低带隙（〜1-1.5 eV）的过渡金属二分法（TMD）将种植并与具有HCSCS制造的超级固有界面的石墨烯相结合。 HC动力学包括HC，温度，HC寿命和载体乘积的类型，将通过时间和角度分辨光发射光谱进行研究，以探测太阳光驱动的HC光伏特征。优化的石墨烯/TMD VDW异质结构将与适当的能量选择性接触（ESC）和金属电极集成，并具有适当的工作功能，用于HCSC中的有效HCS收集。 ESC的厚度将调整为通过ESC的最大HCS隧穿到金属电极的最大隧道。 HC驱动光伏的演示将通过电流 - 电压（I-V）测量进行，并具有各种能量激光照明。大面积的HCSC将通过太阳能模拟器下的VDWS材料和I-V测量值的晶状尺度生长实现（1-SUN AM1.5）。