Hansen Chase, Unruh Davis, Alba Miguel, Qian Caroline, Abelson Alex, Law Matt, Zimanyi Gergely T
Physics Department, University of California, Davis, USA.
Chemistry Department, University of California, Irvine, USA.
Sci Rep. 2021 Apr 2;11(1):7458. doi: 10.1038/s41598-021-86790-2.
The efficiency of nanoparticle (NP) solar cells has grown impressively in recent years, exceeding 16%. However, the carrier mobility in NP solar cells, and in other optoelectronic applications remains low, thus critically limiting their performance. Therefore, carrier transport in NP solids needs to be better understood to further improve the overall efficiency of NP solar cell technology. However, it is technically challenging to simulate experimental scale samples, as physical processes from atomic to mesoscopic scales all crucially impact transport. To rise to this challenge, here we report the development of TRIDENS: the Transport in Defected Nanoparticle Solids Simulator, that adds three more hierarchical layers to our previously developed HINTS code for nanoparticle solar cells. In TRIDENS, we first introduced planar defects, such as twin planes and grain boundaries into individual NP SLs superlattices (SLs) that comprised the order of 10 NPs. Then we used HINTS to simulate the transport across tens of thousands of defected NP SLs, and constructed the distribution of the NP SL mobilities with planar defects. Second, the defected NP SLs were assembled into a resistor network with more than 10 NP SLs, thus representing about 10 individual NPs. Finally, the TRIDENS results were analyzed by finite size scaling to explore whether the percolation transition, separating the phase where the low mobility defected NP SLs percolate, from the phase where the high mobility undefected NP SLs percolate drives a low-mobility-to-highmobility transport crossover that can be extrapolated to genuinely macroscopic length scales. For the theoretical description, we adapted the Efros-Shklovskii bimodal mobility distribution percolation model. We demonstrated that the ES bimodal theory's two-variable scaling function is an effective tool to quantitatively characterize this low-mobility-to-high-mobility transport crossover.
近年来，纳米颗粒（NP）太阳能电池的效率显著提高，已超过16%。然而，NP太阳能电池以及其他光电子应用中的载流子迁移率仍然很低，这严重限制了它们的性能。因此，需要更好地理解NP固体中的载流子传输，以进一步提高NP太阳能电池技术的整体效率。然而，模拟实验规模的样品在技术上具有挑战性，因为从原子尺度到介观尺度的物理过程都会对传输产生至关重要的影响。为了应对这一挑战，我们在此报告TRIDENS的开发：缺陷纳米颗粒固体中的传输模拟器，它在我们之前为纳米颗粒太阳能电池开发的HINTS代码基础上增加了三个层次。在TRIDENS中，我们首先将平面缺陷，如孪晶面和晶界引入到由大约10个NP组成的单个NP超晶格（SL）中。然后我们使用HINTS模拟数万个有缺陷的NP SL之间的传输，并构建了有平面缺陷的NP SL迁移率分布。其次，将有缺陷的NP SL组装成一个由10多个NP SL组成的电阻网络，从而代表大约10个单个NP。最后，通过有限尺寸标度分析TRIDENS结果，以探索渗流转变是否驱动了从低迁移率缺陷NP SL渗流的相到高迁移率未缺陷NP SL渗流的相之间的低迁移率到高迁移率的传输转变，这种转变可以外推到真正的宏观长度尺度。对于理论描述，我们采用了Efros-Shklovskii双峰迁移率分布渗流模型。我们证明了ES双峰理论的双变量标度函数是定量表征这种低迁移率到高迁移率传输转变的有效工具。
