纳米结构在太阳电池上的新应用研究

发布时间：2018-05-05 13:11

本文选题：硅基异质结 + 光场调控　；参考：《上海交通大学》2015年博士论文

【摘要】：光伏发电是解决人类能源需求和维持可持续发展的重要途径。在不断推动太阳电池效率提升的进程中,纳米结构在器件上的应用已经展示出了巨大的潜力,成为了近年来备受关注的研究热点。由于纳米结构独特的光学、电学、材料特性,其在优化太阳电池的减反陷光、载流子输运、结构设计等方面都有广泛的利用价值。可以预见,对纳米结构的深入研究和深化应用将继续主导第三代高效太阳电池的开发和推广。然而值得注意的是,纳米结构在太阳电池上的应用仍然是一个较新的领域,还不断涌现着大量的新结构被提出、研究、并最终提升电池的效率。目前对纳米结构的使用形式一般还停留在对电池单一的光学或电学性能的优化,因此基本都是在传统电池框架范围内的某种延伸。在这种条件下,具有纳米结构的太阳电池多数仍然受制于普通电池的结构缺陷和理论效率极限,特别是再考虑到纳米结构对表面复合等因素的不利影响,使得实际的效率提升空间被大大压缩。显然,还需要不断挖掘该类电池的潜力来实现真正的效率突破。在本文中,我们着重从理论模拟的角度来探究纳米结构在光伏器件上可能的新应用形式,试图加深对其特定性质的理解并拓展其功能的范畴。首先,我们提出了在硅基异质结电池前表面引入周期性纳米柱阵列,通过其对短波光场的调制来改善电池内量子效率的方式。我们发现,通过适当的控制阵列的结构参量,可以使入射光激发柱中的共振腔模和阵列的导模,使得光场的较强处、即电池的吸收前沿有效地从高缺陷的非晶硅层转移到低缺陷的单晶硅中,大大提高了载流子的收集效率,并最终提升电池在该波段的短路电流达38%以上。该结果启发了一种新的光学-电学综合式的效率提升途径。其次,我们研究了单根竖直纳米线这一新概念电池的光电特性以及其对平面宏观器件理论极限的突破潜力。我们首次指出了其光学行为可以由可见光波段的介质共振天线来描述,填补了之前理论无法定量分析的缺陷。在此基础上,我们发现通过适当选择基模激发的峰位,并引入背反射面,可以使其内建聚光达到最大的21倍,进而使其开路电压超过shockley-queisser极限达124mv;另一方面,由于其漏模共振的吸收机制,该类电池的载流子产生主要集中在中部本征层中而非表面高缺陷层中,使得其具有高于平面结构的输运能力以及对缺陷复合的高耐受性。最终其效率超过平面极限达33%以上。最后,我们将上述的单根竖直纳米线电池推广到了宏观器件的情形。我们发现在将其组装为二维阵列时,两个关键的因素是维持单个基元电池的内建聚光以及基元共振腔陷光和阵列光子学陷光的互补式设计。为此,我们提出使用同轴介质包覆层来实现共振腔模式的调控,以取代传统的半径调控方式。最终,我们展示了转换效率高于平面极限达30%以上的宏观光伏器件,为下一代高效电池的设计提供了全新的思路。
[Abstract]:Photovoltaic power generation is an important way to solve the human energy demand and sustain the sustainable development. In the process of promoting the efficiency of solar cell efficiency, the application of nanostructures on the devices has shown great potential. It has become a hot research focus in recent years. Due to the unique optical, electrical, material properties of the nanostructures, It can be widely used in optimizing the sunk sunk, carrier transport, structure design and so on. It is foreseeable that the in-depth study and further application of nanostructures will continue to dominate the development and popularization of the third generation high efficiency solar cells. However, it is worth noting that the application of nanostructures to solar cells is still the same. A new field, and a large number of new structures are emerging, studied, and ultimately improved the efficiency of the battery. The current use of nanostructures generally remains in the optimization of the single optical or electrical properties of the battery, so it is basically a kind of extension within the traditional battery frame range. Under this condition, it is available. Most of the nanoscale solar cells are still subject to the structural defects and theoretical efficiency limits of ordinary batteries, especially considering the adverse effects of nanostructures on surface composite factors, making the actual efficiency space greatly compressed. It is clear that the potential of this type of battery needs to be continuously excavated to achieve real efficiency breakthroughs. In this paper, we focus on exploring the possible new applications of nanostructures on photovoltaic devices from the theoretical point of view, trying to deepen the understanding of their specific properties and expand their functions. First, we introduce the introduction of periodic nanoscale arrays on the surface of the silicon based heterojunction battery, and the modulation of the short wave field through its modulation. In order to improve the quantum efficiency in the battery, we find that the appropriate control of the structure parameters of the array can make the resonant cavity mode and the guide mode of the array in the incident light excitation, so that the stronger of the light field, that is, the absorption frontier of the battery is effectively transferred from the highly defective amorphous silicon layer to the low defect monocrystalline silicon, which greatly improves the load. The efficiency of the collection of the flow is more than 38%. The results illuminate a new optical and electrical comprehensive efficiency improvement approach. Secondly, we have studied the photoelectric characteristics of the new concept battery, a single vertical nanowire, and the breakthrough potential for the theoretical limit of the flat surface macro devices. For the first time, we point out that the optical behavior of the medium can be described by the dielectric resonance antenna in the visible light band and fills the defect that the previous theory can't analyze quantitatively. On this basis, we find that by selecting the peak position of the base mode excitation and introducing the back reflector, the inner building can reach the maximum of 21 times, and then the open circuit voltage can be exceeded. The over Shockley-Queisser limit is 124mv; on the other hand, due to the absorption mechanism of the leaky mode resonance, the carrier generation of this type of battery is mainly concentrated in the central intrinsic layer rather than the surface high defect layer, making it have higher transport capacity than the plane structure and the high tolerance to the defect compound. Finally, the efficiency exceeds the plane limit of 33. In the end, we generalized the above single vertical nanowire cells to the macro devices. We found that the two key factors to be assembled into a two-dimensional array are the maintenance of the built-in light of a single element cell and the complementary design of the resonant cavity and the array photonics. The coaxial dielectric coating is used to control the resonant cavity mode to replace the traditional radius control mode. Finally, we show that the conversion efficiency is higher than the plane limit of more than 30% of the macro photovoltaic devices, which provides a new way of thinking for the design of the next generation efficient battery.

【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;TM914.4

【相似文献】