Deuteration-functionalized self-assembled monolayers for UV-durable perovskite solar cells

Ultraviolet (UV) light-induced degradation at the buried interface poses a significant challenge to the long-term stability of perovskite solar cells (PSCs), resulting in substantial efficiency losses and hindering their commercialization. Here, we developed two simple deuterated self-assembled monolayers (SAMs), 2DPh-4PACz and 1DPh-4PACz. In particular, 2DPh-4PACz, featuring double deuterophenyl groups as π-conjugated extension units, demonstrates enhanced intrinsic UV stability, improved hole-extraction capability, and effective protection of the perovskite film against UV exposure, while simultaneously improving film quality. As a result, PSCs incorporating 2DPh-4PACz achieved a power conversion efficiency (PCE) of 26.34% (certified 25.9%) and retained 96.9% of their initial PCE after 240 h of continuous UV irradiation, representing the best UV light stability reported to date. Additionally, extensive UV-aging experiments were conducted comparing with Ph-4PACz, confirming deuteration of SAMs as an effective strategy to improve UV resistivity. Moreover, these devices maintained 92.8% of their initial PCE after over 900 h of thermal aging at 85°C, and 73% after more than 1380 h at 80% relative humidity (RH). This deuterophenyl groups design strategy with π-conjugated extension offers a promising molecular design route for next-generation SAMs in high-performance, durable PSCs. (Figure presented.).