Researchers achieve record-set perovskite tandem solar cells with novel NIR harvesting molecules

Scientists at the National University of Singapore (NUS) have demonstrated a perovskite-organic tandem solar cell with a certified world record conversion efficiency of 26.4% in an active area of ​​1 cm2. This milestone is driven by a newly designed narrowband organic absorber that greatly enhances near-infrared (NIR) photon harvesting, a long-standing bottleneck of thin-film tandem solar cells.

This latest research breakthrough is the President’s Young Professor in the Faculty of Chemicals and Biomolecular Engineering at NUS’s Faculty of Design and Engineering, and the President’s Young Professor in the Institute of Solar Energy (SERIS) at the Institute of Solar Energy (SERIS) at NUS’s Singapore Solar Energy (SERIS).

The NUS Research team presented their work in the Nature Journal on June 25th, 2025.

Unlock tandem solar cell promise

Both perovskite and organic semiconductors provide broadly tunable band gups, allowing tandem cells to approach very high theoretical efficiency. “Thanks to its lightweight and flexible form factor, Perovskite-organic tandem solar cells are ideally suited for power applications that run directly on devices such as drones, wearable electronics, smart fabrics and other AI-enabled devices,” Asst said. Professor Who.

However, the overall efficiency of tandem cells has been improved due to the lack of efficient NIR thin film absorbers that help capture sunlight more efficiently in the NIR region.

Uses near infrared

To overcome this challenge, Asst. Professor Hou and his team developed an asymmetric organic acceptor with an expanded conjugated structure, allowing absorption deep into the NIR region while maintaining sufficient driving force for efficient charge separation and promoting ordered molecular packaging. Ultrafast spectroscopy and device physics analysis confirmed that this design achieves high free charge carrier collection with minimal energy loss.

Based on the performance of the organic subcells, researchers have interfaced with transparent conductive oxide (TCO)-based interconnectors stacked under the high-efficiency perovskite top cells in two layers.

The newly designed tandem cell achieves a power conversion efficiency of 27.5% for 0.05 cm2 samples and 26.7% for 1 cm2 devices, with 26.4% independently certified results. These findings demonstrate the highest certified performance ever between comparable size perovskite, organic, perovskite, and single-function perovskite cells.

“Because they are poised to exceed 30% efficiency, these flexible films are ideal for roll-to-roll production and seamless integration into curved or fabric substrates. Think of a self-capable health patch that captures sunlight to run onboard sensors, or a smart textile that monitors biometric authentication without the need for bulky batteries.” Professor Who.

In the next phase of their research, the NUS team will focus on improving real-world operational stability and advances towards pilot line manufacturing. This is an important step in bringing flexible, high-performance solar technology to the market.