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

Abstract 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 of 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.