Self-assembled monolayers with cross-linkable header on the linker for durable perovskite photovoltaics

Perovskite solar cells (PSCs) using self-assembled monolayers (SAMs) as hole transporting materials have achieved impressive efficiencies. However, the vulnerability of SAMs causes desorption under light and thermal stress. While various modifications to the conjugated core and anchoring group of SAMs have been explored, challenges in balancing efficiency and stability remain. Here, we introduce a new class of cross-linkable SAMs, uniquely functionalized at the molecular linker. Upon in situ cross-linking, these hybrid monolayers exhibit impressive conductivity and optimal energy level alignment, enabling a power conversion efficiency (PCE) of 26.76% (certified 26.45%) in PSCs. The perovskite solar cells with cross-linkable SAMs also demonstrate superior durability in ageing tests, retaining 99% of its initial PCE under more than 2000 hours thermal stress and 95% of that under 500 hours ultraviolet irradiation. Furthermore, the strategy has been applied in the fabrication of high-efficiency rigid and flexible mini-modules. This molecular design strategy offers a promising and versatile modification site for advancing SAMs-based interfaces in optoelectronic devices.