Obtaining Large Columnar CdTe Grains and Long Lifetime on Nanocrystalline CdSe, MgZnO, or CdS Layers
Obtaining Large Columnar CdTe Grains and Long Lifetime on Nanocrystalline CdSe, MgZnO, or CdS Layers
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DOI：
10.1002/aenm.201702666
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发表时间：
2018-04-16
影响因子：
27.8
通讯作者：
Metzger, Wyatt K.
中科院分区：
文献类型：
--
作者：
Amarasinghe, Mahisha;Colegrove, Eric;Metzger, Wyatt K.
碲化镉太阳能电池已经达到了与多晶硅相当的效率，并以与传统能源竞争的成本生产电力。最近的效率提高部分来自于从传统的CdS窗口层转移到新材料，如CdSe和MgZnO，但仍存在大量的空间来提高性能。包括Cu（In，Ga）Se-2、钙钛矿、Cu 2 ZnSn（S，Se）（4）和CdTe的薄膜技术固有地具有许多可以形成复合中心并阻碍载流子传输的晶界;然而，晶界工程一直是困难的并且不实用。在这项工作中，它表明，通过整个碲化镉层达到宽柱状晶粒可以通过积极的沉积后碲化镉重结晶实现。这减少了由成核作用对纳米晶窗口层施加的晶粒结构约束，并且使得能够针对电光应用的关键的其它性质来选择不同的窗口层。计算模拟表明，晶粒尺寸从1 μ m增加到7 μ m，可以相当于减少晶界复合速度的三个数量级。在这里，大的高质量晶粒使CdTe寿命超过50 ns。
CdTe solar cells have reached efficiencies comparable to multicrystalline silicon and produce electricity at costs competitive with traditional energy sources. Recent efficiency gains have come partly from shifting from the traditional CdS window layer to new materials such as CdSe and MgZnO, yet substantial headroom still exists to improve performance. Thin film technologies including Cu(In,Ga)Se-2, perovskites, Cu2ZnSn(S,Se)(4), and CdTe inherently have many grain boundaries that can form recombination centers and impede carrier transport; however, grain boundary engineering has been difficult and not practical. In this work, it is demonstrated that wide columnar grains reaching through the entire CdTe layer can be achieved by aggressive postdeposition CdTe recrystallization. This reduces the grain structure constraints imposed by nucleation on nanocrystalline window layers and enables diverse window layers to be selected for other properties critical for electro-optical applications. Computational simulations indicate that increasing grain size from 1 to 7 mu m can be equivalent to decreasing grain-boundary recombination velocity by three orders of magnitude. Here, large high-quality grains enable CdTe lifetimes exceeding 50 ns.