# Mimicking nature to develop halide perovskite semiconductors from proteins and metal carbonates

## TL;DR

Researchers developed a new method to create stable halide perovskite structures using proteins and metal carbonates, enabling customizable 3D shapes for various applications.

## Contribution

A novel biomineralization and ion exchange approach to fabricate tunable 3D halide perovskite structures with controlled morphology.

## Key findings

- Biomolecules and ion exchange reactions were combined to control the shape and composition of halide perovskite nanostructures.
- Core–shell composites of metal carbonates and perovskites were fabricated into diverse 3D architectures suitable for sensors and detectors.
- Disposable humidity sensors with a detection range of 11–95% were successfully created using the bio-templated composites on paper substrates.

## Abstract

Halide perovskite (HPs) nanostructures have recently gained extensive worldwide attentions because of their remarkable optoelectronic properties and fast developments. However, intrinsic instability against environmental factors—i.e., temperature, humidity, illumination, and oxygen—restricted their real-life applications. HPs are typically synthesized as colloids by employing organic solvents and ligands. Consequently, the precise control and tuning of complex 3D perovskite morphologies are challenging and have hardly been achieved by conventional fabrication methods. Here, we combine the benefits of self-assembly of biomolecules and an ion exchange reaction (IER) approach to customize HPs spatial shapes and composition. Initially, we apply a biomineralization approach, using biological templates (such as biopolymers, proteins, or protein assemblies), modulating the morphology of MCO3 (M = Ca2+, Ba2+) nano/microstructures. We then show that the morphology of the materials can be maintained throughout an IER process to form surface HPs with a wide variety of morphologies. The fabricated core–shell structures of metal carbonates and HPs introduce nano/microcomposites that can be sculpted into a wide diversity of 3D architectures suitable for various potential applications such as sensors, detectors, catalysis, etc. As a prototype, we fabricate disposable humidity sensors with an 11–95% detection range by casting the formed bio-templated nano/micro-composites on paper substrate.