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

PI：伊戈尔·L·库斯科夫斯基提议编号：1512017太阳代表着地球上最丰富的潜在可持续能源。由被称为量子点的纳米晶体薄膜制成的太阳能电池，可能比目前商业使用的晶硅太阳能电池更便宜、更高效。该项目的目标是设计量子点的组成和大小，以加强对太阳光谱中紫外线和红外波长的太阳能的收集，从而产生潜在的高太阳能转换效率和功率输出。量子点将由锌、硒、镉和碲等元素的混合物制成，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。这项拟议的研究可能会导致发现新的太阳能转换量子力学过程。作为与该项目相关的教育活动的一部分，首席调查员将通过皇后学院暑期科学计划指导高中生在纽约州举行的科学博览会竞赛中与纳米技术相关的项目。拟议研究的总体目标是开发第二类量子点光伏(PV)半导体材料，使其能够在宿主材料的带隙以下吸收光，从而导致更高的太阳能转换效率。为此，将第二类量子点嵌入到宽带隙半导体主体中，利用材料体系和合成方法，在不损失开路电压的情况下，将具有光子吸收特性的中间带隙材料映射到紫外到红外范围内的太阳光谱。为此，该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。候选材料体系由嵌有锌(Cd)Te-ZnCdSe-Ⅱ类量子点的p-ZnSeTe/Zn(Cd)Te-ZnCdSe/n-ZnCdSe结构组成。与InP衬底匹配的势垒具有约2.1 eV的带隙，而量子点的价带偏移为0.8-1.0 eV。这些参数将通过控制量子点的大小和化学成分来实现。为了实现对中间带的有效部分填充，将设计一种交替掺杂量子点层的结构。薄膜生长将被设计成避免形成润湿层，从而降低最终材料的开路电压。这一过程还将允许沉积数百个无缺陷的量子点层，以改善光吸收。器件级模拟将描述器件配置和与这些中间带隙材料相关的复合过程之间的相互作用。在这项研究的基础上，将开发用于太阳能电池应用的第二类量子点制造的教学材料，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的课程。

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.