Anti-aggregation self-assembled monolayers enable high-performance and scalable perovskite solar cells
Kaihuai Du, Chunna Huang, Aili Wang, Haoran Zhang, LvZhou Li, X. F. Dong, Luozheng Zhang, Mohammad Khaja Nazeeruddin, Guixiang Li, Jianning Ding
Abstract
Stable self-assembled monolayers (SAMs), such as (2-(9H-carbazol-9-yl)) ethylphosphonic acid (2PACz), are crucial for reducing interfacial energy loss in high-performance perovskite solar cells (PSCs). However, the inherent aggregation tendency of SAMs at the buried interface hinders the device's performance. Here, we propose a surfactant-assisted strategy to inhibit the aggregation of 2PACz by functionalizing cetyltrimethylammonium bromide (CTAB). Capitalizing on its distinctive electrostatic potential distribution, CTAB engages in non-bonding interactions with 2PACz. Theoretical and experimental characterizations prove that this promotes the uniform dispersion and anchoring of 2PACz on the substrate, leading to the SAM formation with high surface potential and excellent coverage. Moreover, the perovskite films with CTAB-modified SAM exhibit enhanced crystallinity with reduced trap state density and improved hole extraction efficiency. Consequently, the PSCs with a p-i-n architecture achieve a power conversion efficiency (PCE) of 26.20% (0.072 cm²). Scaled-up modules attain a PCE of 22.34% (22.96 cm²), confirming the scalability. Additionally, anti-aggregation-SAMs-integrated devices demonstrate stability, maintaining over 80% and 90% of their initial PCEs after tracking at maximum power point for 800 h and ageing at 65 °C for 1000 h, respectively.