In-situ buried interface passivation enables efficient and stable inverted perovskite solar modules

Scaling-up perovskite solar cells (PSCs) is a prerequisite to the adoption of perovskite photovoltaics. However, the performance and stability of perovskite solar modules (PSMs) have lagged behind those of lab-scale PSCs. The development o PSMs requires interfacial passivation, yet this is challenging for the buried interface, owing to the dissolution of passivation agents during perovskite deposition. Here, we overcome this limitation with in-situ buried interface passivation – achieved via directly adding a cyanoacrylic acid-based molecular additive, namely BT-T, into the perovskite precursor solution. Classical and ab-initio molecular dynamics (MD) simulations reveal that BT-T spontaneously self-assembles at the buried interface during perovskite film formation. The preferential buried interface passivation results in facilitated hole transfer and suppressed surface recombination. In addition, residual BT-T molecules in the perovskite layer enhance its stability and homogeneity. We report a power-conversion efficiency (PCE) of 20.3% for inverted-structure PSMs. The encapsulated PSM retains 92.5% of its initial PCE (20.2%) following 1817 h maximum power point (MPP) tracking under light illumination at 65 °C, corresponding to a T80 (time to 80% of initial PCEs) of 4500 h. Our demonstration of operating-stable PSMs under accelerated ageing represents a step closer to the commercialization of this emerging technology.