Ultraviolet (UV)-induced damage and limited solar spectrum utilization can hinder the performance of perovskite solar cells (PSCs). In a recent study, researchers from Fuzhou University and Chinese Academy of Sciences developed a thermally activated delayed fluorescent (TADF) molecule, 4CzIPN, to address these challenges.
Acting as a down-conversion agent, 4CzIPN can convert UV light to visible light via Förster energy transfer, enhancing light absorption and reducing photon loss. Additionally, it can bind Pb2+ defects and prevents organic cation degradation through cationic π-effects, stabilizing the perovskite structure. By serving as a crystal growth site, 4CzIPN can promote intermediate phase formation and delay the crystallization process, and improve film quality while mitigating residual stress due to its high thermal expansion coefficient. Furthermore, its UV filtration and hydrophobic properties would reduce perovskite decomposition and device degradation.
These advancements yielded a device with a power conversion efficiency (PCE) of 24.23 % and enhanced optoelectronic properties.
The modified device demonstrated outstanding moisture and UV light stability, retaining 90 % of its initial efficiency after 1680 h under ambient conditions (25 ± 5°C, 15 ± 5 % RH) without any encapsulation.
The team successfully incorporated a TADF molecule 4CzIPN as an additive in the perovskite layer for the first time. Its benefits could advance the commercialization of PSCs by overcoming such challenges as insufficient light absorption due to limited bandgap and inadequate long-term stability under operational conditions.
