Control of Recombination Pathways in TiO2 Nanowire Hybrid Solar Cells Using Sn4+ Dopants
Control of Recombination Pathways in TiO2 Nanowire Hybrid Solar Cells Using Sn4+ Dopants
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DOI：
10.1021/jp412650r
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发表时间：
2014-07-31
影响因子：
3.7
通讯作者：
Schmidt-Mende, Lukas
中科院分区：
文献类型：
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作者：
Dorman, James A.;Weickert, Jonas;Schmidt-Mende, Lukas
由于低成本材料组合的可用性，混合纳米结构作为硅太阳能电池的替代品已显示出越来越大的潜力。然而，到目前为止，混合太阳能电池的效率有限，其中光子吸收发生在半导体聚合物中，电荷分离发生在金属氧化物-聚合物界面上。一个限制是由金属氧化物中相对较低的载流子迁移率引起的。在这里，我们解决了这个问题，并描述了使用 Sn:TiO2 垂直棒 TiO2、核壳纳米线阵列来增加纳米线核中的电荷载流子迁移率，同时减少金属氧化物聚合物界面处的电荷载流子复合，这是由于从纳米线壳到核的级联导带能量驱动，从该界面快速提取电子。与参考 TiO2 基器件相比，这些具有未掺杂壳结构的掺杂核使 3396 混合太阳能电池的效率显着提高。此外，根据光电压衰减测量和阻抗谱，该器件结构的复合寿命增加了 17%。提出了核和核壳系统的复合机制，以突出 Sn4+ 掺杂 TiO2 纳米线阵列的各种效应。掺杂核壳结构具有在混合型器件中应用的潜力，而不受当前双金属氧化物结构所见的限制，因为金属氧化物主体的无缝界面可将电子直接传输到高迁移率核材料中。
Hybrid nanostructures have shown increasing potential as a replacement for Si solar cells due to the availability of low-cost material combinations. However, up to now, hybrid solar cells, where photon absorption occurs in a semiconducting polymer and charge separation occurs at a metal oxide-polymer interface, show limited efficiencies. One limitation is caused by a relative low charge carrier mobility in the metal oxide. Here we addressed this issue and describe the use of a Sn:TiO2 vertical bar TiO2, core shell nanowire array to increase the charge-carrier mobility in the core of the nanowires while decreasing the charge-carrier recombination at the metal oxide polymer interface due to fast electron extraction from this interface, driven by a cascaded conduction band energy from shell to core of the nanowires. These doped cores with an undoped shell structure resulted in impressive efficiency improvement in hybrid solar cells of 3396 over the reference TiO2-based device. Additionally, this device structure resulted in a 17% increase in recombination lifetimes based on both photovoltage decay measurements and impedance spectroscopy. Recombination mechanisms are proposed for the core and core shell systems to highlight the various effects of the Sn4+-doped TiO2 nanowire arrays. Doped core shell structures have the potential for application in the hybrid-type devices without the limitations that are seen with the current dual metal oxide structures due to the seamless interface of the metal oxide host for direct transport of the electrons into the highly mobile core material.