Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China.
Institute of Materials for Optoelectronics and New Energy, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China.
Adv Mater. 2019 Sep;31(37):e1901673. doi: 10.1002/adma.201901673. Epub 2019 Aug 5.
Low-dimensional Ruddlesden-Popper perovskites (RPPs) exhibit excellent stability in comparison with 3D perovskites; however, the relatively low power conversion efficiency (PCE) limits their future application. In this work, a new fluorine-substituted phenylethlammonium (PEA) cation is developed as a spacer to fabricate quasi-2D (4FPEA) (MA) Pb I (n = 5) perovskite solar cells. The champion device exhibits a remarkable PCE of 17.3% with a J of 19.00 mA cm , a V of 1.16 V, and a fill factor (FF) of 79%, which are among the best results for low-dimensional RPP solar cells (n ≤ 5). The enhanced device performance can be attributed as follows: first, the strong dipole field induced by the 4-fluoro-phenethylammonium (4FPEA) organic spacer facilitates charge dissociation. Second, fluorinated RPP crystals preferentially grow along the vertical direction, and form a phase distribution with the increasing n number from bottom to the top surface, resulting in efficient charge transport. Third, 4FPEA-based RPP films exhibit higher film crystallinity, enlarged grain size, and reduced trap-state density. Lastly, the unsealed fluorinated RPP devices demonstrate superior humidity and thermal stability. Therefore, the fluorination of the long-chain organic cations provides a feasible approach for simultaneously improving the efficiency and stability of low-dimensional RPP solar cells.
低维的 Ruddlesden-Popper 型钙钛矿（RPP）与三维钙钛矿相比具有优异的稳定性；然而，相对较低的功率转换效率（PCE）限制了其未来的应用。在这项工作中，开发了一种新的氟取代的苯乙基铵（PEA）阳离子作为间隔物，以制备准二维（4FPEA）（MA）Pb I（n = 5）钙钛矿太阳能电池。冠军器件的光电转换效率（PCE）高达 17.3%，J 为 19.00 mA cm ，V 为 1.16 V，填充因子（FF）为 79%，这是低维 RPP 太阳能电池（n ≤ 5）中最好的结果之一。增强的器件性能可以归因于以下几点：首先，4-氟苯乙基铵（4FPEA）有机间隔物产生的强偶极场有助于电荷离解。其次，氟化 RPP 晶体优先沿垂直方向生长，并随着 n 值的增加从底部到顶部表面形成相分布，从而实现有效的电荷输运。第三，基于 4FPEA 的 RPP 薄膜具有更高的薄膜结晶度、更大的晶粒尺寸和更低的陷阱态密度。最后，未密封的氟化 RPP 器件表现出优异的湿度和热稳定性。因此，长链有机阳离子的氟化提供了一种同时提高低维 RPP 太阳能电池效率和稳定性的可行方法。
