Zu Fengshuo, Amsalem Patrick, Egger David A, Wang Rongbin, Wolff Christian M, Fang Honghua, Loi Maria Antonietta, Neher Dieter, Kronik Leeor, Duhm Steffen, Koch Norbert
Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany.
J Phys Chem Lett. 2019 Feb 7;10(3):601-609. doi: 10.1021/acs.jpclett.8b03728. Epub 2019 Jan 25.
Photovoltaic cells based on halide perovskites, possessing remarkably high power conversion efficiencies have been reported. To push the development of such devices further, a comprehensive and reliable understanding of their electronic properties is essential but presently not available. To provide a solid foundation for understanding the electronic properties of polycrystalline thin films, we employ single-crystal band structure data from angle-resolved photoemission measurements. For two prototypical perovskites (CHNHPbBr and CHNHPbI), we reveal the band dispersion in two high-symmetry directions and identify the global valence band maxima. With these benchmark data, we construct "standard" photoemission spectra from polycrystalline thin film samples and resolve challenges discussed in the literature for determining the valence band onset with high reliability. Within the framework laid out here, the consistency of relating the energy level alignment in perovskite-based photovoltaic and optoelectronic devices with their functional parameters is substantially enhanced.
据报道，基于卤化物钙钛矿的光伏电池具有非常高的功率转换效率。为了进一步推动此类器件的发展，全面而可靠地了解其电子特性至关重要，但目前尚无法做到。为了为理解多晶薄膜的电子特性提供坚实基础，我们采用了角分辨光电子能谱测量得到的单晶能带结构数据。对于两种典型的钙钛矿（CH₃NH₃PbBr₃和CH₃NH₃PbI₃），我们揭示了两个高对称方向上的能带色散，并确定了全局价带最大值。利用这些基准数据，我们从多晶薄膜样品构建了“标准”光电子能谱，并解决了文献中讨论的以高可靠性确定价带起始点的挑战。在此处阐述的框架内，基于钙钛矿的光伏和光电器件中能级排列与其功能参数之间关系的一致性得到了显著增强。
