Role of PbSe Structural Stabilization in Photovoltaic Cells
Role of PbSe Structural Stabilization in Photovoltaic Cells
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DOI：
10.1002/adfm.201401816
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发表时间：
2015-02-11
影响因子：
19
通讯作者：
Friend, Richard H.
中科院分区：
文献类型：
--
作者：
Asil, Demet;Walker, Brian J.;Friend, Richard H.
半导体纳米晶体是用于印刷光电器件的有前途的材料，但其高表面积容易形成阻碍电荷载流子传输的缺陷。此外，硫族化物纳米晶体（NC）材料特性与太阳能电池运行的相关性并不简单，因为在加工过程中常常会在NC薄膜中引入无序。在此，描述了卤化物表面钝化导致的 PbSe NC 对称性长程有序性的改进，并研究了其对化学、光学和光伏器件性能的影响。值得注意的是，这种钝化方法导致 PbSe NC 在配体交换过程中发生纳米级重排，完全通过无机表面化学改善纳米晶体对称性的长程有序性。采用各种结构构建的太阳能电池显示出不同的改进，这表明三线态形成和电离，而不是载流子传输，是单线态裂变太阳能电池的限制因素。与现有方案相比，我们的合成产生的 PbSe 纳米晶体具有表面结合的氯离子、减少的亚带隙吸收以及坚固的材料和器件，其性能特征比未钝化的同类材料和器件的保留时间长很多小时。
Semiconductor nanocrystals are promising materials for printed optoelectronic devices, but their high surface areas are susceptible to forming defects that hinder charge carrier transport. Furthermore, correlation of chalcogenide nanocrystal (NC) material properties with solar cell operation is not straightforward due to the disorder often induced into NC films during processing. Here, an improvement in long-range ordering of PbSe NCs symmetry that results from halide surface passivation is described, and the effects on chemical, optical, and photovoltaic device properties are investigated. Notably, this passivation method leads to a nanometer-scale rearrangement of PbSe NCs during ligand exchange, improving the long-range ordering of nanocrystal symmetry entirely with inorganic surface chemistry. Solar cells constructed with a variety of architectures show varying improvement and suggest that triplet formation and ionization, rather than carrier transport, is the limiting factor in singlet fission solar cells. Compared to existing protocols, our synthesis leads to PbSe nanocrystals with surface-bound chloride ions, reduced sub-bandgap absorption and robust materials and devices that retain performance characteristics many hours longer than their unpassivated counterparts.