English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Halide perovskites excel in the pursuit of highly efficient thin filmphotovoltaics, with power conversion efficiencies reaching 25.5% in singlejunction and 29.5% in tandem halide perovskite/silicon solar cellconfigurations. Operational stability of perovskite solar cells remains abarrier to their commercialisation, yet a fundamental understanding ofdegradation processes, including the specific sites at which failure mechanismsoccur, is lacking. Recently, we reported that performance-limiting deepsub-bandgap states appear in nanoscale clusters at particular grain boundariesin state-of-the-art $Cs_{0.05}FA_{0.78}MA_{0.17}Pb(I_{0.83}Br_{0.17})_{3}$(MA=methylammonium, FA=formamidinium) perovskite films. Here, we combinemultimodal microscopy to show that these very nanoscale defect clusters, whichgo otherwise undetected with bulk measurements, are sites at which degradationseeds. We use photoemission electron microscopy to visualise trap clusters andobserve that these specific sites grow in defect density over time underillumination, leading to local reductions in performance parameters. Scanningelectron diffraction measurements reveal concomitant structural changes atphase impurities associated with trap clusters, with rapid conversion tometallic lead through iodine depletion, eventually resulting in pinholeformation. By contrast, illumination in the presence of oxygen reduces defectdensities and reverses performance degradation at these local clusters, wherephase impurities instead convert to amorphous and electronically benign leadoxide. Our work shows that the trapping of charge carriers at sites associatedwith phase impurities, itself reducing performance, catalyses redox reactionsthat compromise device longevity. Importantly, we reveal that both performancelosses and intrinsic degradation can be mitigated by eliminating thesedefective clusters.

Local Nanoscale Defective Phase Impurities Are the Sites of Degradation in Halide Perovskite Devices