Deconvolution of Light‐Induced Ion Migration Phenomena by Statistical Analysis of Cathodoluminescence in Lead Halide‐Based Perovskites

Abstract

Studying the compositional instability of mixed ion perovskites under light illumination is important to understand the mechanisms underlying their efficiency and stability. However, current techniques are limited in resolution and are unable to deconvolute minor ion migration phenomena. Here, a method that enables ion migration to be studied allowing different segregation mechanisms to be elucidated is described. Statistical analysis is applied to cathodoluminescence data to generate compositional distribution histograms. Using these histograms, two different ion migration phenomena, horizontal ion migration (HIM) and vertical ion migration (VIM), are identified in different perovskite films. It is found that most passivating agents inhibit HIM, but not VIM. However, VIM can be reduced by deposition of imidazolium iodide on the perovskite surface. This method can be used to study perovskite-based devices efficiency and stability by providing molecular level mechanistic understanding of passivation approaches leading to performance improvement of perovskite solar cells via rational design.

Electron‐Accepting PDI–Cb Interlayer for over 22% Inverted Perovskite Solar Cells with Photo‐ and Thermal Stability

“…Meanwhile, such a diffusion process has been suggested to stem from charge accumulation at the interface and results in the formation of AgI species, leading to degradation in photovoltaic performance. [47][48][49] Therefore, the enhanced charge extraction capability and diffusion barrier property of PDI-Cb interlayer could be ascribed for suppressed ion migration process and thereby contribute to enhanced long-term device stability.…”

Photo-processing of perovskites: current research status and challenges

“…Light illumination is able to create plenty of photocarri-ers, whose separation, accumulation and trapping by the defects lead to generation of an electrical field 56,57 . Consequently, the mobile halide ions are driven by this established field and fill the defects, such as vacancies and interstitials.…”

“…As a result, the phase segregation can be manipulated by controlling the light density, which enables writing-reading-erasing the designed patterns in the perovskites and holds potential in applications of optical data storage. In addition, a two-step illumination technique was developed to exploit the potential of phase segregation in the applications of opto-electronics 57 . Firstly, a 405 nm laser with the power density of 1500 W/cm 2 was used to produce defect patterns with plenty of defect states in CsPb(Cl 1−x Br x ) 3 perovskite microplatelets.…”

Novel Two-Dimensional Graphdiyne-Derived Additive for Stable Inverted Perovskite Solar Cells

“…Nevertheless, the PCE is still lower than the theoretically calculated Shockley–Queisser limit efficiency (30.5%), and the device stability issues have turned into the biggest barrier for the commercialization of the PSCs. Of all the factors that affect the PCE and device stability of PSCs, defect-induced nonradiative recombination was the main factor behind the obstacles . The solution process for fabricating perovskite films usually leads to a great deal of interstitial defects and vacancies as the out-diffusion of organic ions during the heating process.…”

“…Of all the factors that affect the PCE and device stability of PSCs, defect-induced nonradiative recombination was the main factor behind the obstacles. 5 The solution process for fabricating perovskite films usually leads to a great deal of interstitial defects and vacancies as the outdiffusion of organic ions during the heating process. For example, the uncoordinated Pb 2+ existing on the surface of the perovskite and grain boundaries (GBs) serve as nonradiative recombination centers, 6 which could trap the free-moving electrons and holes during the charge transporting process.…”