Innovative polymer materials have what it takes to harvest solar energy in extreme outdoor environments.

Next-generation solar cells made from organic materials could soon contribute to real-world renewable energy generation, suggests an outdoor stress test conducted under intense Saudi Arabian sunlight. The long-term study showed that certain organic light-capturing materials are surprisingly resilient to light-induced ‘photodegradation’ and revealed new ways to further optimize the cells’ longevity in realistic conditionsNature Photonics (2025).| article. " id="return-reference-1" href="https://discovery.kaust.edu.sa/en/article/25539/illuminating-pathways-to-long-lived-organic-solar-cells/#reference-1">[1].

Lightweight, semi-transparent and flexible, organic solar cells (OSCs) could potentially be used in a range of situations where conventional silicon solar panels would be too heavy, rigid or opaque to be deployed. “Recently, OSCs’ solar power conversion efficiencies (PCEs) have improved rapidly, surpassing 20 percent in laboratory settings,” says Han Xu, a postdoc in the KAUST lab of Derya Baran, who led the research with then postdoc Jianhua Han. “However, there has been much less focus on improving long-term stability of OSCs, which remains a major bottleneck hindering commercial viability,” he says.

The performance of an OSC can decline precipitously when exposed to the heat, light and moisture of outdoor environments; this occurs via degradation pathways that are poorly understood. “To bridge this knowledge gap, we systematically investigated the degradation behavior of various OSCs under light, thermal stress, and outdoor conditions,” Xu says.

The researchers focused on a component of the OSC’s light-harvesting core called the polymer donor. These materials’ photodegradation pathways have rarely been studied, despite their crucial role in OSC light absorption, charge generation and transport.

The team made a series of OSCs incorporating different polymer donors and studied the impact of factors such as polymer molecular structure on OSC longevity.

The weak spot of the polymer donors’ key photodegradation, it turned out, was the side chains that branch from the polymers’ central molecular backbone. The team showed that light could knock a hydrogen atom from a side chain or break off a side chain entirely, initiating cascading damage. “This can result in by-products such as cleaved side chains, radicals, twisted polymer backbones, and cross-linked structures,” Xu says.

Read more at KAUST Discovery.