Dučinskas Algirdas, Jung Mina, Wang Ya-Ru, Milić Jovana V, Moia Davide, Grätzel Michael, Maier Joachim
Laboratory of Photonics and Interfaces, École Polytechnique Fédéralé de Lausanne 1015 Lausanne Switzerland
Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany
J Mater Chem C Mater. 2024 May 14;12(22):7909-7915. doi: 10.1039/d4tc01010h. eCollection 2024 Jun 6.
The understanding of mixed ionic-electronic conductivity in hybrid perovskites has enabled major advances in the development of optoelectronic devices based on this class of materials. While recent investigations revealed the potential of using dimensionality effects for various applications, the implication of this strategy on mixed conductivity is yet to be established. Here, we present a systematic analysis of mixed conduction in layered (2D) hybrid halide perovskite films based on 1,4-phenylenedimethylammonium (PDMA) and benzylammonium (BzA) organic spacers in (PDMA)PbI and (BzA)PbI compositions, forming representative Dion-Jacobson (DJ) and Ruddleson-Popper (RP) phases, respectively. Electrochemical measurements of charge transport parallel to the layered structure reveal mixed ionic-electronic conduction with electronic transport mediated by electron holes in both DJ and RP phases. In comparison to the 3D perovskites, larger activation energies for both ionic and electronic conductivities are observed which result in lower absolute values. While the layered perovskites still allow for a relatively efficient exchange of iodine with the gas phase, the lower change of conductivity on the variation of the iodine partial pressure compared with 3D perovskites is consistent with the exchange affecting only a fraction of the film, with implications for the encapsulating efficacy of these materials. We complement the analysis with a demonstration of the superior thermal stability of DJ structures compared to their RP counterparts. This can guide future explorations of dimensionality and composition to control the transport and stabilization properties of 2D perovskite films.
对混合钙钛矿中离子 - 电子混合传导的理解推动了基于这类材料的光电器件发展取得重大进展。尽管最近的研究揭示了利用维度效应实现各种应用的潜力，但这种策略对混合传导的影响尚未明确。在此，我们对基于1,4 - 苯二甲基铵（PDMA）和苄基铵（BzA）有机间隔基的层状（二维）混合卤化物钙钛矿薄膜中的混合传导进行了系统分析，在（PDMA）PbI和（BzA）PbI组成中分别形成代表性的狄龙 - 雅各布森（DJ）相和鲁德森 - 波珀（RP）相。平行于层状结构的电荷传输的电化学测量表明，在DJ相和RP相中，离子 - 电子混合传导是由电子空穴介导的电子传输。与三维钙钛矿相比，离子和电子电导率的活化能更大，导致绝对值更低。虽然层状钙钛矿仍允许碘与气相进行相对有效的交换，但与三维钙钛矿相比，碘分压变化时电导率的变化较小，这与交换仅影响薄膜的一部分一致，对这些材料的封装效果有影响。我们通过证明DJ结构与其RP对应物相比具有更高的热稳定性来补充分析。这可以指导未来对维度和组成的探索，以控制二维钙钛矿薄膜的传输和稳定性能。
