UNS: Performance Optimized Intermediate Band Photovoltaic Devices based on Type-II Quantum Dots

PI: Igor L kuskovsky提案编号：1512017太阳是地球上最丰富的潜在可持续能源。由被称为量子点的纳米级晶体薄膜制成的太阳能电池可能比目前商用的晶体硅太阳能电池更便宜，效率更高。该项目的目标是设计量子点的组成和大小，以增强太阳光谱中紫外和红外波长的太阳能收集，从而潜在地提高太阳能转换效率和功率输出。量子点将由锌、硒、镉和碲元素的混合物制成，作为科学研究的模型化合物。这些混合物的组成将由计算机模拟来指导。提出的研究可能导致发现太阳能转换的新量子力学过程。作为与该项目相关的教育活动的一部分，首席研究员将通过皇后学院暑期科学计划指导高中生参加纽约州科学竞赛的纳米技术相关项目。本研究的总体目标是开发ii型量子点光伏（PV）半导体材料，使其能够在宿主材料的带隙以下吸收光，从而提高太阳能转换效率。为此，ii型量子点将嵌入到宽带隙半导体主机中，利用材料系统和合成方法，在不损失开路电压的情况下增加光电流，从而制造出具有紫外至红外范围内太阳光谱光子吸收特性的中间带隙材料。为此，本研究计划将整合材料合成、带隙计算和光伏器件模拟，以确定理想的中间带隙光伏材料。候选材料体系由p-ZnSeTe/Zn(Cd)Te-ZnCdSe/n-ZnCdSe结构和嵌入Zn(Cd)Te-ZnCdSe ii型量子点组成。与InP衬底相匹配的晶格势垒具有约2.1 eV的带隙，而量子点具有0.8-1.0 eV的价带偏移。这些参数将通过控制量子点尺寸和化学成分来实现。为了实现有效的中间带的部分填充，将设计一个具有交替掺杂量子点层的结构。薄膜的生长将被设计成避免形成可以降低最终材料开路电压的润湿层。这一过程也将允许几百个无缺陷量子点层的沉积，以提高光吸收。器件级模拟将描述与这些中间带隙材料相关的器件配置和重组过程之间的相互作用。基于该研究，将开发用于太阳能电池应用的ii型量子点制造主题的教学材料，并将用于纽约城市学院皇后学院光子学专业硕士学位课程。

PI: Igor L KuskovskyProposal Number: 1512017The sun represents the most abundant potential source of sustainable energy on earth. Solar cells made from thin films of nanometer-sized crystals called quantum dots are potentially less expensive and more efficient than crystalline silicon solar cells currently in commercial use. The goal of this project is to engineer the composition and size of the quantum dots to enhance the collection of solar energy in the ultraviolet and infrared wavelengths of the solar spectrum, resulting in potentially high solar energy conversion efficiency and power output. The quantum dots will be made from mixtures of the elements zinc, selenium, cadmium, and tellurium as model compounds for scientific study. The composition of these mixtures will be guided by computer simulations. The proposed research may lead to the discovery of new quantum mechanical processes for solar energy conversion. As part of the educational activities associated with the project, the principal investigator will mentor high school students through Queens College Summer Science Program on nanotechnology related projects for science fair competitions in the state of New York. The overall goal of the proposed research is to develop Type-II quantum-dot photovoltaic (PV) semiconductor materials that enable the absorption of light below the band gap of the host material, leading to higher solar energy conversion efficiency. Toward this end, Type-II quantum dots will be imbedded into a wide band-gap semiconductor host to make an intermediate band gap material with photon absorption characteristics mapped to the solar spectrum in the ultraviolet to infrared range, using material systems and synthesis approaches that lead to increase of photocurrent without loss of open circuit voltage. Toward this end, the research plan will integrate material synthesis, band gap calculations, and PV device simulation to identify ideal intermediate band gap PV materials. The candidate material systems consist of a p-ZnSeTe/Zn(Cd)Te-ZnCdSe/n-ZnCdSe structure with embedded Zn(Cd)Te-ZnCdSe type-II quantum dots. The barriers, latticed matched to the InP substrate, have the bandgaps of about 2.1 eV, while the quantum dots have a valence band offset of 0.8-1.0 eV. These parameters will be achieved by controlling quantum dot size and chemical composition. To accomplish effective partial filling of the intermediate band, a structure with alternatively doped quantum dot layers will be engineered. Film growth will be designed to avoid formation of a wetting layer that can lower the open circuit voltage of the final material. This process will also allow for the deposition of several hundred defect-free quantum dot layers for improved light absorption. Device-level simulation will characterize the interplay between device configuration and recombination processes associated with these intermediate band gap materials. Based on the research, instructional material will be developed on the topic of fabrication of Type-II quantum dots for solar cell applications, and will be used in courses for a professional Master's degree program in Photonics at Queens College, The City College of New York.