A joint research team led by Southeast University and Soochow University has found a way to stop the molecular fighting in flexible perovskite solar cells. To turn rigid solar tech into bendable panels that can roll over backpacks or car roofs, researchers had to fix a major manufacturing flaw in flexible perovskite solar cells.
Printing these flexible devices requires depositing two layers at once. A ultrathin foundational transport layer called a single-molecule film (self-assembled monolayer, SAM), and the light-harvesting perovskite crystals
When engineers tried to coat them together onto bendable substrates, the SAM molecules and perovskite components bound too strongly to each other instead of taking their proper positions. This chemical feud left behind uneven, defect-ridden layers that broke down under operational heat and humidity.
The joint research team solved this chemical roadblock by introducing a customized “decoupling” molecule. The discovery acts as an atomic referee. It prevents the two components from reacting prematurely and unlocks reliable, large-scale production.
“A 25-square-centimeter flexible device retained 92.5 percent of its initial PCE of 22 percent after 1044 hours of maximum power point tracking at 85°C (185°F) and 65 percent relative humidity,” the study paper noted.
Fixing the problem
Flexible substrates have uneven surface roughness and varying hydroxyl-group densities, making standard large-area printing techniques ineffective. Attempting a conventional co-deposition strategy improves surface wettability, yet strong intermolecular interactions between transport layer molecules and perovskite components disrupt both substrate anchoring and crystal formation. These chemical conflicts ultimately leave current flexible solar modules far behind their rigid counterparts in both efficiency and stability.
Researchers introduced a “decoupled co-deposition” strategy to improve large-area flexible perovskite solar modules.
The approach resolves the challenge of uniformly printing transport layers and perovskite films onto flexible substrates. It provides a practical chemical solution to boost both the conversion efficiency and operational stability of flexible solar devices.
To fix the chemical interference, the research team added a decoupling modulator molecule featuring ammonium ions, iodide ions, and two sulfonate groups to the precursor solution.
This additive forms strong chelating bonds with the perovskite framework. It blocks harmful interactions between transport layer molecules and perovskite components. With the interference removed, the transport molecules can quickly stick to the flexible base, while the new additive guides crystal growth and seals up flaws in the perovskite layer.
Technique works well in testing
This strategy optimizes both the transport and perovskite layers together, driving efficiency and durability to record levels.
The results hit record numbers. Small-area flexible cells achieved a third-party certified efficiency of 26.86 percent. Scaling up yielded record module efficiencies across the board: 22.31 percent for 5×5 cm² panels, 20.63 percent for 10×10 cm² panels, and 20.15 percent for large 30×30 cm² sheets.
Durability held up under pressure too. The flexible modules survived thermal shock cycles from frigid lows to extreme heat and passed the rigorous IEC 63163 international stability standard.
“More important, this strategy facilitates the modules to pass the industry-standard IEC 63163 stability series certification, providing an important foundation for the industrial development of flexible perovskite photovoltaics,” the team stated.
This collaborative work delivers a new chemical strategy for fabricating high-performance flexible perovskite modules in China.
Future research will focus on refining decoupling molecules, integrating tandem cell designs, and scaling production for roll-to-roll manufacturing. These developments support the modernization of renewable energy systems and help drive national carbon-reduction goals.
The findings were published in the journal Science.