# Structure and composition of grain boundaries and their impact on functional properties of energy materials

## TL;DR

This paper examines how the structure and composition of grain boundaries affect the performance of energy materials like those used in batteries and solar cells.

## Contribution

The paper introduces a framework to correlate grain boundary structure, composition, and electronic properties to optimize energy material performance.

## Key findings

- Grain boundary transitions can reduce resistance in solid electrolytes by promoting grain growth.
- Electric fields can induce boundary transitions affecting transport properties.
- Potential barriers at grain boundaries can be tuned by modulating chemical composition and carrier concentration.

## Abstract

This article explores the impact of grain boundary structures and compositions on the functional properties of various materials for photovoltaics, batteries, and other energy-related applications. Examples of correlative microscopy studies highlight the potential to discover structure–property relationships at grain boundaries, essential for the design of energy devices to achieve superior performance. A grain boundary transition that promotes grain growth and reduces the boundary resistance in solid electrolytes is given as an example. A key focus will be on transport phenomena at grain boundaries, including mass, thermal, electrical, and ionic transport mechanisms. These transport phenomena are directly correlated with the charge defects that lead to a buildup of electric charges and potential barriers at the grain boundaries. In addition, applied electric fields can also induce boundary transitions that can affect grain boundary transport and other properties. Finally, we demonstrate that these potential barrier heights can be tuned by modulating the chemical composition, structure, and carrier concentration of the grain boundaries.

Obtaining grain boundaries (GBs) with superior properties based on the correlation between the structure, composition, and electronic properties at the GB level.

Obtaining grain boundaries (GBs) with superior properties based on the correlation between the structure, composition, and electronic properties at the GB level.

The online version contains supplementary material available at 10.1557/s43577-025-01038-y.