Multi-stacked hybrid graphene and quantum dot films for high response photodetection

标题：用于高响应光电检测的混合石墨烯和量子点膜非技术：光到电的转换是光检测和光伏器件的核心，这些器件对相机、快速通信、信息处理、生物检测、生物医学仪器和能量收集至关重要。光探测的主要挑战之一是开发低功耗的新技术，这些技术可以薄而灵活，便于在可穿戴和便携式设备上使用。该项目旨在开发一种混合超薄技术，将半导体纳米粒子(量子点)的强烈光吸收与单原子厚碳层(石墨烯)的高导电性相结合。该项目的策略是使用量子点收集光线并产生电荷，这些电荷将被插入石墨烯的层收集，以实现高效的电荷传输。嵌入的石墨烯层将作为光电探测器内部电荷的高导电路径的有效网络。将这些纳米材料结合在一起，将使超薄光电探测器具有高灵敏度和低功耗，可以在灵活和可穿戴的设备上实现。该项目还将建立一个平台，培训新一代学生和工程师，了解用于光电子学和太阳能收集应用的纳米材料的性质和应用。此外，该项目还将有助于向代表性不足的社区传播纳米技术的新进展，特别是在南加州地区西班牙裔社区的高中。技术：该项目的目标是开发具有增强光响应的硫化铅量子点光探测器，使用嵌入的石墨烯层进行有效的电流收集。众所周知，为了利用传统的顶/底接触进行有效的电流提取，吸收层的厚度不应超过载流子扩散长度。如果薄膜较厚，则光载体在被顶部/底部电极收集之前重新结合。该项目旨在通过使用间距小于载流子扩散长度的插层来克服这一限制，从而允许在它们重新结合之前有效地收集光电荷。这是一种创新的策略，旨在打破扩散长度对光吸收层施加的限制，从而提高光电子器件的性能。该项目的第一个目标将是研究石墨烯/量子点界面上的电荷转移动力学和光响应。这两种材料已经得到了大量的研究，但它们的联合杂化异质结在很大程度上仍未被探索。由于两者都是量子受限系统，具有强烈的表面依赖行为，因此电荷转移可能与正常的体结有很大不同。构建插层量子点和石墨烯器件的技术将基于与这两种纳米材料兼容的低温处理，如量子点的旋涂和石墨烯转移。将不同的纳米材料集成到一个器件中，可以为开发结合它们的特性的高性能纳米器件开辟一条新的途径。我们对这些设备的分析将基于光吸收、光响应性和量子效率测量。这些测量将集中于研究吸收层厚度和石墨烯层之间的间距对性能的提高。该项目有可能开发一种具有优异载流子收集效率的光电子器件的新架构。

Title: Hybrid graphene and quantum dot films for high response photodetectionAbstractNon-technical: Conversion of light to electricity is at the core of photodetection and photovoltaic devices that are critical for cameras, fast communications, information processing, biodetection, biomedical instruments, and energy harvesting. One of the main challenges for light detection is developing new technologies with low power consumption that can be thin and flexible to facilitate its use on wearable and portable devices. This project aims to develop a hybrid and ultrathin technology combining the strong light absorption of semiconducting nanoparticles (quantum dots) with the high electrical conductivity of one-atom thick carbon layers (graphene). The strategy for this project is to use quantum dots to collect light and generate electrical charges that will be collected by intercalated graphene layers for efficient charge transport. The intercalated graphene layers will serve as an efficient network of highly conductive paths for electrical charges inside the photodetector. Combining these nanomaterials would allow ultrathin photodetectors with high sensitivity and low power consumption that can be implemented on flexible and wearable devices. This project will also set a platform to train a new generation of students and engineers on the properties and applications of nanomaterials for optoelectronics and sunlight energy harvesting applications. Furthermore, this project will also help to disseminate new advances in nanotechnology for underrepresented communities, especially in high-schools in Hispanic communities in the region of Southern California.Technical: The goal for this project is to develop lead-sulfide quantum dot photodetectors with enhanced photoresponse using intercalated graphene layers for efficient current collection. It is a well-known restriction that for efficient current extraction with conventional top/bottom contacts, the thickness of the absorbing layers should not exceed the carrier diffusion length. If the films are thicker, then the photocarriers recombine before being collected by the top/bottom electrodes. This project aims to overcome this restriction by using intercalated layers with spacing shorter than the carrier diffusion length, allowing the efficient collection of photocharges before they recombine. This is an innovative strategy to break the limitation that diffusion length imposes on light absorbing layers and therefore boost the performance of optoelectronic devices. The first goal of the project will be to study the charge transfer dynamics and photoresponse at a graphene/quantum dot interface. Both materials have been largely studied, but their joint hybrid heterojunction is still largely unexplored. Since both are quantum confined systems with strong surface dependent behavior, the charge transfer can substantially differ from normal 'bulk' junctions. The technology to build the intercalated quantum dots and graphene devices will be developed based on low-temperature processing compatible with both nanomaterials, such as spin coating of quantum dots and graphene transfer. Integrating different nanomaterials in a single device can open a new route to develop high performing nanoscale devices combining their properties. Our analysis of the devices will be based on light absorption, photoresponsivity, and quantum efficiency measurements. The measurements will focus on studying the performance enhancement as function of the thickness of the absorbing layer and the spacing between graphene layers. This project has the potential to develop a new architecture for optoelectronic devices with superior carrier collection efficiency.