Improving the stability of methylammonium lead iodide perovskite solar cells by cesium doping
Improving the stability of methylammonium lead iodide perovskite solar cells by cesium doping
复制标题
通过铯掺杂提高甲铵碘化铅钙钛矿太阳能电池的稳定性
DOI：
10.1016/j.tsf.2018.10.001
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发表时间：
2018-12-01
期刊：
影响因子：
2.1
通讯作者：
Zhong, Dingyong
中科院分区：
文献类型：
--
作者：
Fan, Yuman;Qin, Helin;Zhong, Dingyong
有机金属卤化物钙钛矿太阳能电池被认为是光伏技术领域的一项显著进展。然而，钙钛矿太阳能电池的稳定性差成为制约其商业化应用的一个严重问题。本文研究了铯离子在甲基碘化铅钙钛矿太阳能电池中的掺杂及其对器件稳定性的影响。铯在碘化铅甲基铵中均匀掺杂，浓度可达15%。对于掺杂的太阳能电池，与未掺杂的电池相比，在没有明显损失的情况下，效率达到了13.2-16.5%。更重要的是，铯的掺杂大大提高了器件的稳定性。在黑暗大气环境中放置7天和30天后，未掺杂20%铯的器件的初始效率分别为83%和60%，而未掺杂的电池的初始效率分别为59%和25%。密度泛函理论计算表明，铯掺杂剂比甲基铵阳离子带更多正电荷。同时，铯的掺杂使碘的平均电荷增加。因此，甲基铵离子与[PbI6]八面体骨架之间的库仑相互作用得到加强，这被认为是阻止甲基铵离子扩散从而稳定钙钛矿结构的有效因素。
Organometal halide perovskite solar cells are regarded as a remarkable progress in the field of photovoltaic technology. However, the poor stability of perovskite solar cells becomes a serious issue restricting the commercial applications. Here, we investigate the doping of cesium cations in methylammonium lead iodide perovskite solar cells and the effect on the device stability. Homogeneous doping of cesium into methylammonium lead iodide has been obtained with a concentration up to 15%. For the doped solar cells, an efficiency of 13.2-16.5% has been achieved without significant loss compared with the undoped cells. More importantly, the device stability has been dramatically improved by cesium doping. After staying in a dark atmospheric environment for 7 and 30 days, the unencapsulated devices with 20% cesium doping retained 83% and 60% of the initial efficiency, while the undoped cells remained only 59% and 25% of the initial efficiency, respectively. Density functional theory calculations suggest that the cesium dopants are more positively charged than the methylammonium cations. Meanwhile, the doping of cesium increases the averaged charge of iodines. As a result, the Coulomb interactions between the methylammonium cations and the framework of [PbI6] octahedrons are strengthened, which is considered as an efficient factor to prohibit the diffusion of methylammonium cations and therefore stabilize the perovskite structure.