# B-Site Mixing Effects in Hybrid Perovskites: Phase Transitions and Dielectric Response of MAPb1–xSnxBr3

## TL;DR

This study explores how mixing lead and tin at the B-site in a hybrid perovskite affects its structure and performance for solar cells.

## Contribution

The paper provides the first comprehensive analysis of B-site mixing effects in MA-based perovskites.

## Key findings

- B-site mixing slightly stabilizes the cubic phase of MAPb1–xSnxBr3.
- Mixing affects MA cation dynamics and ordering but less than A- or X-site mixing.
- The study reveals insights into structural and dynamic properties for photovoltaic optimization.

## Abstract

Ion-mixing is a highly effective strategy for tuning
the performance
and stability of photovoltaic devices based on hybrid perovskites.
Despite many works concentrating on the A- and X-site mixing effects,
a comprehensive study on the effects of B-site mixing on the structural
and dynamic properties of MA-based perovskites is still absent. In
this work, we investigate the structural and dynamic properties of
mixed lead–tin halide perovskites MAPb1–xSnxBr3 using
a multitechnique experimental approach including differential scanning
calorimetry, dielectric spectroscopy, and nuclear quadrupole resonance
experiments. We map the phase diagram of this system, which reveals
that B-site mixing slightly stabilizes the cubic phase and affects
the MA cation dynamics and ordering, although the observed effects
are less prominent compared with A- and X-site mixing. Our results
provide insights into the complex interplay of structural and dynamic
properties in mixed-metal perovskites contributing to their potential
optimization for photovoltaic applications.