Subdiffraction Infrared Imaging of Mixed Cation Perovskites: Probing Local Cation Heterogeneities
Subdiffraction Infrared Imaging of Mixed Cation Perovskites: Probing Local Cation Heterogeneities
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DOI：
10.1021/acsenergylett.7b01306
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发表时间：
2018-02-01
影响因子：
22
通讯作者：
Kuno, Masaru
中科院分区：
文献类型：
--
作者：
Chatterjee, Rusha;Pavlovetc, Ilia M.;Kuno, Masaru
复合材料工程极大地提高了混合钙钛矿太阳能电池的稳定性和性能。混合阳离子钙钛矿已成为光伏材料的冠军，其功率转换效率超过22%。然而，对于混合阳离子钙钛矿薄膜中与局部阳离子相关的成分不均匀性的研究相对较少。这样的研究是必要的，因为杂化钙钛矿的光学性质，因此，它们的光伏性能在很大程度上取决于成分。在这里，我们进行了空间分辨，亚衍射红外光热外差成像测量，以探测FA(x)MA(1-x)PBI(3)钙钛矿薄膜中阳离子特异性成分分布。我们的测量结果表明，这些钙钛矿具有很大的组成空间异质性，阳离子分布平均变化幅度与预期的系综化学计量学相似，约为20%。相关发射测量显示，由于这些成分的差异，膜内发射能量相差超过30兆电子伏。这些测量结果揭示了阳离子的化学非均质性及其对局部光伏响应的直接影响，从而决定了混合阳离子钙钛矿的光学性质。
Compositional engineering has led to dramatic improvements in hybrid perovskite-based solar cell stabilities and performance. Mixed cation perovskites have emerged as champion photovoltaic materials with power conversion efficiencies exceeding 22%. However, there has been relatively little work done to explore local cation-related compositional inhomogeneities in mixed cation perovskite films. Such studies are necessary because hybrid perovskite optical properties and, consequently, their photovoltaic performance strongly depend on composition. Here, we perform spatially resolved, subdiffraction infrared photo thermal heterodyne imaging measurements to probe cation-specific compositional distributions within FA(x)MA(1-x)PBI(3) perovskite films. Our measurements reveal that these perovskites possess large compositional spatial heterogeneities with cation distributions varying on average similar to 20% from expected ensemble stoichiometries. Correlated emission measurements show intrafilm emission energies differing by over 30 meV due to these compositional differences. These measurements thus reveal cation stoichiometric heterogeneities and their direct impact on local photovoltaic response-determining opticalproperties of mixed cation perovskites.