A Mechanically Robust Conducting Polymer Network Electrode for Efficient Flexible Perovskite Solar Cells

Lightweight and mechanically flexible photovoltaics enable roll-to-roll processing, which improves their potential for low-cost mass production. However, the lack of highly conductive and transparent flexible electrodes still causes reduced efficiency relative to solar cells formed on rigid substrates. Here, we demonstrate an electrode that reduces this performance gap in perovskite solar cells (PSCs) by regulating the phase separation of a conducting polymer network using a fluorosurfactant dopant. This network electrode simultaneously offers high conductivity (>4,000 S/cm), improved transmittance (over 80% from 400 to 900 nm), and high mechanical endurance. PSCs with this electrode achieve stabilized power conversion efficiencies of 19.0% and 10.9% at aperture areas of 0.1 cm2 and 25 cm2, respectively, which is comparable to control devices on rigid substrates. This electrode further shows promise as the top electrode in semi-transparent PSCs, which show a stabilized efficiency of 12.5% at 30.6% average visible transmittance. Each of these cells exhibits strong mechanical stability, retaining 80% at 25 cm2, 85% at 0.1 cm2, and 90% for semi-transparent devices of their original efficiency after 5,000 bending cycles at a curvature radius of 3 mm.