A research team from the National University of Singapore has developed a novel perovskite-organic tandem solar cell, certified to achieve a power conversion efficiency (PCE) of 26.4% within a 1 cm² active area—setting a new world record for such devices. The findings were published in the latest issue of Nature.

The team emphasized that the newly developed tandem cell combines ultra-thinness and flexibility, enabling future direct integration into AI-powered equipment such as drones, smart textiles, and wearable devices to provide clean energy.

Breakthrough Innovation: Narrow-Bandgap Organic Absorber

At the core of this advancement lies the team’s pioneering narrow-bandgap organic absorber. Functioning as a precision "photon trap," it efficiently captures photons in the near-infrared (NIR) region, successfully overcoming a long-standing technical bottleneck in thin-film tandem solar cell development.

While the tunable bandgaps of perovskite and organic semiconductor materials offer potential to surpass theoretical efficiency limits, low NIR absorption has persistently hindered progress.

Innovative Molecular Design

To address this challenge, the team devised an asymmetric organic acceptor. This structure not only extends the light-absorption range into deep-NIR regions but also maintains sufficient charge-separation driving force while enabling highly ordered molecular alignment. Through ultrafast spectroscopy and device physics analysis, the team confirmed that this design achieves efficient charge collection with minimal energy loss.

Device Integration and Performance

In practice, the researchers stacked this high-performance organic subcell with a top perovskite cell, integrating them via a transparent conductive oxide interlayer. Key results include:

● 27.5% PCE for a 0.05 cm² micro-device

● 26.7% PCE for a standard 1 cm² device

● 26.4% independently certified efficiency for the 1 cm² cell

This achievement not only breaks the perovskite-organic tandem record but also outperforms same-sized perovskite-CIGS and single-junction perovskite cells.