# Flexo-Pyroelectric Effect

## TL;DR

Researchers discovered a new way to generate electricity from temperature changes using materials that were previously thought to be unsuitable, opening up new possibilities for sustainable energy.

## Contribution

The study introduces the flexo-pyroelectric effect, enabling centrosymmetric materials to exhibit pyroelectricity through strain engineering.

## Key findings

- A giant pyroelectric coefficient of up to 1.25 × 10⁶ μC·m⁻²·K⁻¹ was achieved in SrTiO₃ using strain gradients.
- The flexo-pyroelectric effect decouples pyroelectric functionality from material polarity.
- Centrosymmetric materials can now be used for pyroelectric energy harvesting, overcoming symmetry limitations.

## Abstract

Developing sustainable energy technologies is among the foremost challenges of this century and spawns the emergence of materials for ambient energy harvesting, such as photovoltaics, triboelectrics, and pyroelectrics. The conversion of ambient thermal energy (temperature fluctuations) into electricity through pyroelectric materials offers a promising route toward sustainable energy technologies. However, there is a critical limitation: The conventional pyroelectric effect is inherently restricted to noncentrosymmetric crystals, but excludes the centrosymmetric materials, even though they exhibit otherwise favorable properties. This symmetry dependence severely constrains the development of pyroelectric energy technology. Here, we demonstrate that the pyroelectric effect, typically observed only in noncentrosymmetric materials, can be induced in centrosymmetric materials via the flexoelectric effect. By introducing strain gradients using an atomic force microscope, we generated a giant pyroelectric coefficient of up to 1.25 × 106 μC·m−2·K−1 in SrTiO3. This strain gradient-induced pyroelectric effect, termed as the flexo-pyroelectric effect, decouples pyroelectric functionality from intrinsic material polarity. Our findings exceed the long-standing symmetry limitation in pyroelectric energy technology by proving that centrosymmetric materials can also exhibit robust pyroelectricity through strain engineering. The flexo-pyroelectric effect redefines the understanding of pyroelectricity and unlocks the vast library of centrosymmetric materials for designing next-generation energy harvesters, advancing sustainable technology development.