Flexible All-Perovskite Tandem Solar Cells Hit 25.4% Efficiency by Solving Interface Flaws

Solar power has historically been anchored by weight. Heavy, rigid silicon panels dominate the market, but they fail to address the needs of portable electronics or aerospace applications where every gram matters. While flexible alternatives promise liberation from these constraints, they have historically bled efficiency at their microscopic seams. This study shatters that ceiling.

The research team identified a specific, hidden bottleneck within the hole transport layer, known as PEDOT:PSS. They measured a previously unrecognised vertical phase segregation. Essentially, an insulating skin rich in PSS forms on top of the conductive base, creating electric dipoles that act like invisible walls against charge extraction. This structural flaw has silently throttled performance for years.

Optimising Flexible All-Perovskite Tandem Solar Cells

To dismantle this barrier, the scientists introduced Triton X-100. This additive acts as a molecular mixer. It disrupts the segregation, ensuring a uniform, conductive path for energy to flow. The impact on flexible all-perovskite tandem solar cells is immediate and measurable. By suppressing surface dipole formation, the modified interface allows holes to escape efficiently, drastically improving the device's fill factor.

The data is robust. The study reports a power conversion efficiency (PCE) of 25.4% for the flexible tandem cells. Scalability looks promising too. A proof-of-concept mini-module reached 19.7% efficiency. Theoretical modelling suggests that with further refinement, module efficiencies could soon exceed 24%. These figures indicate that we are rapidly approaching a tipping point where flexible photovoltaics are not just a novelty, but a primary power source for the next generation of technology.