The Effect of Surface Modifications on Charge Carrier Mobility in Metal Halide Perovskite Thin Films

The efficiency and stability of perovskite solar cells (PSCs) are highly dependent on interfacial dynamics, as the multiple interfaces within the layered structure of a PSC can act as sites for non-radiative recombination losses or harmful degradation reactions¹. In recent years, introducing passivating materials such as polymers or self-assembled monolayers at PSC interfaces has gained popularity. These interlayers can reduce surface recombination, increase long-term stability, and even improve the crystallinity and grain size of the perovskite layer^2,3. However, the effect of such surface modifications on the bulk transport of charge carriers within the film is largely unexplored. Given the “soft” lattice and high surface-to-volume ratio of perovskite thin films, surface conditions often have an outsized effect on bulk properties³. Among these properties, charge carrier mobility is essential to understand, as it directly contributes to PSC efficiency. In this work, time-resolved photoluminescence microscopy is utilized to measure charge carrier mobilities in perovskite thin films with various surface modifications. Through this analysis, we aim to increase the fundamental understanding of the effects of passivating layers, offering insight into the intelligent design of high-efficiency PSCs.<br/><br/><b>References:</b><br/>1. Xiao, Y., Yang, X., Zhu, R. & Snaith, H. J. Unlocking interfaces in photovoltaics. <i>Science</i> <b>384</b>, 846–848 (2024).<br/>2. Kim, S. Y., Cho, S. J., Byeon, S. E., He, X. & Yoon, H. J. Self-Assembled Monolayers as Interface Engineering Nanomaterials in Perovskite Solar Cells. <i>Adv. Energy Mater.</i> <b>10</b>, 2002606 (2020).<br/>3. Xue, J., Wang, R. & Yang, Y. The surface of halide perovskites from nano to bulk. <i>Nat. Rev. Mater.</i> <b>5</b>, 809–827 (2020).