Conformational Elasticity at the Buried Interface: 26.89% Perovskite Solar Cells and 23.95% Certified Modules.

Conventional self-assembled monolayers (SAMs) are conformationally rigid. They cannot buffer interfacial strain during rapid perovskite crystallization, limiting both film quality and device stability. We introduce a conformational engineering strategy using 2-benzhydrylidene-succinic acid (BSA), a rigid diphenylmethylene anchor with flexible succinic acid chains to create an elastic buried interface. Atomic simulations show BSA acts as a compressible buffer, delaying stress accumulation by ∼6 Å under displacement. This dynamic strain dissipation improves heterojunction contact and enhances hole extraction and transport. BSA-modified p-i-n devices reach 26.89% (0.045 cm2, certified 26.52%). Large-area modules (22.95 cm2) deliver 24.30% (certified 23.95%), which is among the highest certified values for this area. The devices retain 90% of initial efficiency after 316 h of diurnal cycling and 88% after 300 extreme transient thermal shock cycles from -20 °C to 100 °C. This conformational design integrates mechanical compliance with electronic functionality in scalable perovskite photovoltaics.