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

Lead-halide perovskites have attracted much attention over the past decade, while two main issues, i.e., the lead-induced toxicity and materials' instability, limit their further practice in widespread applications. To overcome these limitations, an effective alternative is to design lead-free perovskite materials with the substitution of two divalent lead ions with a pair of monovalent and trivalent metal ions. However, fundamental physics and chemistry about how tuning material's composition affects the crystal phase, electronic band structures, and optoelectronic properties of the material have yet to be fully understood. In this work, we conducted a series of density functional theory calculations to explore the mechanism that how various monovalent metal ions influence the crystal and electronic structures of lead-free Cs2MBiCl6 perovskites. We found that the Cs2MBiCl6 (M = Ag, Cu, and Na) perovskites preferred a cubic double perovskite phase with low carrier effective masses, while the Cs2MBiCl6 (M = K, Rb, and Cs) perovskites favored a monoclinic phase with relatively high carrier effective masses. The different crystal phase preferences were attributed to the different radii of monovalent metal cations and the orbital hybridization between the metal and Cl ions. The calculation showed that all Cs2MBiCl6 perovskites studied here exhibited indirect bandgaps. Smaller bandgap energies for the perovskites with a cubic phase were calculated than those of the monoclinic phase counterparts. Charge density difference calculation and electron localization functional analysis were also conducted and revealed that the carrier mobility can be improved via changing the characteristics of metal-halide bonds through compositional and, thus, crystal structure tuning. Our study shown here sheds light on the future design and fabrication of various lead-free perovskite materials for optoelectronic applications.

The effects of monovalent metal cations on the crystal and electronic structures of Cs2MBiCl6 (M = Ag, Cu, Na, K, Rb, and Cs) perovskites