Predictive Modeling of Ion Migration Induced Degradation in Perovskite Solar Cells

Abstract

-With excellent efficiencies being reported from multiple labs across the world, device stability and the degradation mechanisms have emerged as the key aspects that could determine the future prospects of perovskite solar cells. However, the related experimental efforts remain scattered due to the lack of any unifying theoretical framework. In this context, here we provide a comprehensive analysis of ion migration effects in perovskite solar cells. Specifically, we show, for the first time, that (a) the effect of ionic charges is almost indistinguishable from that of dopant ions, (b) ion migration could lead to simultaneous improvement in Voc and degradation in Jsc -a unique observation which is beyond the realm of mere parametric variation in carrier mobility and lifetime, (c) champion devices are more resilient towards the ill effects of ion migration, and finally (d) we propose unique characterization schemes to determine both magnitude and polarity of ionic species. Our results, supported by detailed numerical simulations and direct comparison with experimental data, are of broad interest and provide a much needed predictive capability towards the research on performance degradation mechanisms in perovskite solar cells.

Ion-migration and carrier-recombination inhibition by the cation-π interaction in planar perovskite solar cells

“…Furthermore, ion migration under external electric field is considered as causing the accumulation of mobile ions at the interfaces [34]. Therefore, ion migration plays an important role in device hysteresis behavior [35][36][37]. In MAPbI 3…”

Highly Sensitive Terahertz Thin-Film Total Internal Reflection Spectroscopy Reveals in Situ Photoinduced Structural Changes in Methylammonium Lead Halide Perovskites

“…Representative errorbars are given in Figure 3 respectively. The faster degradation speed of MAPbI2Br1 was likely caused by ion migration 25 in MAPbI2Br1 as there is a more severe lattice mismatch with increasing bromine concentration [11][12]26 . The PL results in Figure S2 also confirmed this: the peak shift of MAPbI2Br1 is more significant than that of MAPbI2.5Br0.5 spectra.…”

Gaining Insight into the Effect of Organic Interface Layer on Suppressing Ion Migration Induced Interfacial Degradation in Perovskite Solar Cells

“…first revealed that perovskite is an ionic–electronic conductor, [ 9 ] many theoretical modeling and experimental results indicate that the intrinsic ions of perovskite (e.g., MA + , Pb + , I − ) have lower activation energies which result in the diffusion of these ions under low external bias or illumination conditions, leading to the rapid degradation of perovskites. [ 10–12 ] Meanwhile, the electromigration of I − ion corrodes the electrodes which severely influence the device performance. [ 13 ] Moreover, in regular structure of PSCs, the most widely used hole transport layer, 2,2′,7,7′‐tetrakis( N , N ‐di‐ p ‐methoxyphenylamine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD) usually requires dopants, for example, lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) to enhance the conductivity.…”