Effects of Small Polar Molecules (MA⁺ and H₂O) on Degradation Processes of Perovskite Solar Cells

Abstract

Degradation mechanisms of methylammonium lead halide perovskite solar cells (PSCs) have drawn much attention recently. Herein, the bulk and surface degradation processes of the perovskite were differentiated for the first time by employing combinational studies using electrochemical impedance spectroscopy (EIS), capacitance frequency (CF), and X-ray diffraction (XRD) studies with particular attention on the roles of small polar molecules (MA and HO). CF study shows that short-circuit current density of the PSCs is increased by HO at the beginning of the degradation process coupled with an increased surface capacitance. On the basis of EIS and XRD analysis, we show that the bulk degradation of PSCs involves a lattice expansion process, which facilitates MA ion diffusion by creating more efficient channels. These results provide a better understanding of the roles of small polar molecules on degradation processes in the bulk and on the surface of the perovskite film.

High-throughput analysis of the ideality factor to evaluate the outdoor performance of perovskite solar minimodules

“…For instance, the convex pattern has been observed for encapsulated PSCs stored at room temperature, for which the P max loss was attributed to interface deterioration inducing interfacial recombination, along with perovskite layer degradation related to the formation of deeper defect states 41 . The linear and convex patterns have both previously been observed in nonencapsulated cells under controlled relative humidity conditions, depending on the PbI 2 /MAI ratio 42 , while the concave pattern has been observed in encapsulated cells exposed to different levels of sunlight, suggesting that light intensity is the main variable that accelerates the degradation process 14 .…”

2D Perovskites with Short Interlayer Distance for High‐Performance Solar Cell Application

“…Then the perovskite precursor solutions were spin coated at 3000 rpm followed by solvent annealing at 120 °C for 10 min. Finally, devices were finished by thermal deposition of C 60 , 2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline (BCP, Lumtec) and Ag electrode …”

Fractional deviations in precursor stoichiometry dictate the properties, performance and stability of perovskite photovoltaic devices

“…The diffusivity and reactivity of these species results in device degradation, which is further accelerated by the presence of moisture, heat or light. 51,55,[59][60][61] Furthermore, based on first principle calculations, MAI terminated surfaces have been suggested to be more prone to water ingress when compared to PbI2 terminated ones. 62,63 So, while slightly overstoichiometric precursor solutions result in favorable surface energetics and an overall higher initial VOC and PCE, they suffer from reduced stability due to the increased amount of MA + and Ispecies at the surface.…”