Improving the Performance of Formamidinium and Cesium Lead Triiodide Perovskite Solar Cells using Lead Thiocyanate Additives
Improving the Performance of Formamidinium and Cesium Lead Triiodide Perovskite Solar Cells using Lead Thiocyanate Additives
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使用硫氰酸铅添加剂提高甲脒和铯三碘化铅钙钛矿太阳能电池的性能
DOI：
10.1002/cssc.201601027
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发表时间：
2016
期刊：
影响因子：
8.4
通讯作者：
Yan Yanfa
中科院分区：
文献类型：
--
作者：
Yu Yue;Wang Changlei;Grice Corey R.;Shrestha Niraj;Chen Jing;Zhao Dewei;Liao Weiqiang;Cimaroli Alex;er J.;Rol;Paul J.;Ellingson R;y J.;Yan Yanfa
甲脒三碘化铅（FAPbI 3）由于其较低的带隙和较好的热稳定性而被认为是甲基铵三碘化铅（MAPbI 3）的替代物。然而，由于FA阳离子的大尺寸，难以合成高质量的FAPbI 3薄膜而不形成不期望的黄相。较小尺寸的阳离子，如MA和Cs，已成功地用于抑制黄相的形成。虽然FA和MA三碘化铅钙钛矿太阳能电池（PVSC）的功率转换效率（PCE）高于20%，但甲脒和三碘化铯铅（FA 1-xCsxPbI 3）PVSC的PCE仅为约16.5%。在此，我们报告了我们对限制（FA 1 − xCsxPbI 3）PVSC PCE的主要因素的检查。我们发现，一个主要的限制因素可能是小晶粒尺寸（约120 nm），这导致相对较短的载流子寿命。 我们进一步发现，向前驱体中添加少量的硫氰酸铅[Pb（SCN）2]可以扩大（FA 1 − xCsxPbI 3）钙钛矿薄膜的晶粒尺寸，并显着增加载流子寿命。因此，我们能够制造（FA 1 − xCsxPbI 3）PVSC，其开路电压和填充因子显著提高，从而增强PCE。当Pb（SCN）2的添加量为0.5mol%时，在反向（正向）电压扫描下，平面FA 0.8Cs0.2PbI3PVSC的平均PCE从16.18±0.50（13.45±0.78）%提高到18.16±0.54（16.86±0.63）%.如果在反向（正向）电压扫描下测量，冠军电池的PCE为19.57（18.12）%，这与性能最佳的含MA平面FA基卤化铅PVSC相当。
Formamidinium lead triiodide (FAPbI3) is considered as an alternative to methylammonium lead triiodide (MAPbI3) because of its lower band gap and better thermal stability. However, owing to the large size of FA cations, it is difficult to synthesize high‐quality FAPbI3thin films without the formation of an undesirable yellow phase. Smaller sized cations, such as MA and Cs, have been successfully used to suppress the formation of the yellow phase. Whereas FA and MA lead triiodide perovskite solar cells (PVSCs) have achieved power conversion efficiencies (PCEs) higher than 20 %, the PCEs of formamidinium and cesium lead triiodide (FA1−xCsxPbI3) PVSCs have been only approximately 16.5 %. Herein, we report our examination of the main factors limiting the PCEs of (FA1−xCsxPbI3) PVSCs. We find that one of the main limiting factors could be the small grain sizes (≈120 nm), which leads to relatively short carrier lifetimes. We further find that adding a small amount of lead thiocyanate [Pb(SCN)2] to the precursors can enlarge the grain size of (FA1−xCsxPbI3) perovskite thin films and significantly increase carrier lifetimes. As a result, we are able to fabricate (FA1−xCsxPbI3) PVSCs with significantly improved open‐circuit voltages and fill factors and, therefore, enhanced PCEs. With an optimal 0.5 mol % Pb(SCN)2additive, the average PCE is increased from 16.18±0.50 (13.45±0.78) % to 18.16±0.54 (16.86±0.63) % for planar FA0.8Cs0.2PbI3PVSCs if measured under reverse (forward) voltage scans. The champion cell registers a PCE of 19.57 (18.12) % if measured under a reverse (forward) voltage scan, which is comparable to that of the best‐performing MA‐containing planar FA‐based lead halide PVSCs.