# Correlative molecular-to-mesoscale evolution in conjugated polymers for intrinsically stretchable organic photovoltaics

## TL;DR

This paper explores how the structure of conjugated polymer films changes under strain, linking these changes to performance in stretchable solar cells.

## Contribution

The study reveals a two-stage structural response in conjugated polymers under deformation, offering new design principles for stretchable electronics.

## Key findings

- Conjugated polymer thin films show a two-stage morphological response during deformation.
- Structural adaptations influence mechanical resilience and photovoltaic performance.
- Chain alignment and torsion govern stress dissipation and optical absorption.

## Abstract

Conjugated polymer thin films offer a unique combination of tunable optoelectronic properties and mechanical flexibility, making them as promising materials for intrinsically stretchable optoelectronic devices. However, achieving both mechanical robustness and high device performance remains a key challenge. Addressing this requires a fundamental understanding of how molecular and mesoscale structures evolve under mechanical strain. Here, we employ a comprehensive suite of X-ray spectroscopy and scattering techniques to investigate the multiscale structural evolution of conjugated polymer thin films during uniaxial deformation. We uncover a two-stage morphological response: an initial stage characterized by polymer chain alignment and rapid crystallite disruption, followed by continued chain orientation accompanied by intrachain torsion at higher strains. These correlative structural adaptations govern key material properties, including stress dissipation, optical absorption, and photovoltaic performance. Our findings establish a mechanistic framework for understanding deformation in semiconducting polymers and provide design principles for developing mechanically robust, high-performance stretchable electronics.

Mechanical response of semiconducting polymers affects their electrical properties, yet the detail remains elusive. Zhong et al. examine the multiscale structural evolution of conjugated polymer thin films during uniaxial deformation and link it to mechanical resilience and solar cell performance.