Group-III-nitride nanowires: electrical and optical properties in view of applications in solarcells

E2项目的目的是设计（In）GaN纳米棒（NR）太阳能电池，探索不同的电池概念。需要特别注意NR的掺杂、大表面的钝化以及NR的尺寸、形状和组装的优化，以在尽可能小的层厚度中获得对太阳光的最佳吸收。可以基于来自各个NR以及系综中的NR的光学、电学和结构表征的反馈来实现对嵌入在附加电介质层中的NR系综的光学和电学性质的仔细控制，并且依赖于物理性质的先前模拟和建模。最终，将使用限定的照明（AM 1.5）确定新型NR基材料的光伏（PV）特性，并将依赖于适当接触方案的开发。对于NR基复合材料的优化，深入了解NR与其环境的相互作用是至关重要的。特别是以下任务/主题将得到解决：·NR与有机分子和无机钝化层的相互作用以及对Voc的影响; ·为了理论上理解NR/分子或NR/钝化层界面处的电子缺陷态和原子缺陷结构，将与合作伙伴合作进行密度泛函理论计算; ·NR与入射光的相互作用：针对最佳光吸收优化NR的尺寸、形状和组装;使用三维全波矢量有限元法（FEM）确定最佳光吸收的模拟支持;·NR与吸收增强层/结构（诸如具有高In含量的量子点层、透明导电氧化物（TCO）层）的相互作用，等离子体激元活性纳米结构金属层、电介质纳米颗粒层增强NR中的光散射并因此最终增强NR中的吸收;·评估涉及径向或轴向p-i-n结以及半导体-绝缘体-半导体（SIS）的不同NR基电池概念基于隧道结甚至异质发射极结构的电池，目前构成了硅光伏电池的世界纪录。所有6项任务只能在这个合作研究小组的各个合作伙伴之间密切合作，结合他们的实验，理论和技术专业知识进行。

Aim of the project E2 is the design of (In)GaN nanorod (NR) solarcells, exploring different cell concepts. Special care needs to be taken to doping of NRs, passivation of large surfaces and optimization of size, shape and assembly of NRs to obtain optimum absorption of sun light in as small as possible layer thicknesses. A careful control of optical and electronic properties of the NR ensembles embedded in additional dielectric layers, can be achieved based on feedback from optical, electrical and structural characterization of individual NRs as well as NRs in ensembles and relies on prior simulations and modeling of physical properties. Ultimately, the photovoltaic (PV) properties of the novel NR based materials will be determined using defined illumination (AM1.5) and will rely on the development of proper contacting schemes. For NR based composite materials optimization an intimate understanding of the interaction of NRs with their environment is crucial. In particular the following tasks/topics will be addressed: • interaction of NRs with organic molecules and inorganic passivation layers and the influence on Voc; • for a theoretical understanding of electronic defect states and atomistic defect structure at the NR/molecule or NR/passivation layer interfaces density functional theory calculations will be carried out in collaboration with partners; • interaction of NRs with incident light: optimization of size, shape and assembly of NRs with respect to optimum light absorption; simulation support to determine optimized light absorption using a three-dimensional full-wave vectorial finite element method (FEM); • interaction of NRs with absorption enhancing layers/structures such as quantum dot layers with high In content, transparent conductive oxide (TCO) layers, plasmonically active nanostructured metal layers, dielectric nanoparticle layers enhancing the light scattering and thus ultimately absorption in the NRs; • exploring the doping profile in NRs and its influence on electrical transport properties; • assessment of different NR based cell concepts involving radial or axial p-i-n junctions as well as semiconductor-insulator-semiconductor (SIS) cells that base on a tunneling junction or even heteroemitter structures that at present constitute the world record cell in silicon PV. All 6 tasks can only be performed in close collaboration between various partners in this collaborative research group, with a combination of their experimental, theoretical and technological expertise.