Bulk nano-heterointerface secures molecular contacts in perovskite solar cells

Abstract

The development of molecule-based selective contacts has boosted the power conversion efficiencies of inverted perovskite solar cells. However, these molecular films, often assembled as monolayer or multiple layers on the substrate, are prone to molecular desorption and structural deformation, limiting the long-term stability of devices. This instability, in essence, originates from the weak contacting structure between the transparent conductive oxide and molecular layer, with a limited interface offering insufficient adhering forces to immobilize the molecules. A general architectural strategy that circumvents this fundamental limitation without compromising electronic functionality is highly demanded, but remains underexplored. We now report a universal architecture of a bulk nano-heterointerface that reconstructed the molecule-based selective layer. The substantially increased chemical interface and strengthened binding force between the molecules and rationally designed nanoscale scaffolds greatly improved the device operational stability, achieving high efficiency. The strategy proved versatile, successfully applied to various molecular systems to enhance device performances, and remained effective in upscaled devices produced via scalable blade coating. The weak contact between the oxide electrode and molecular layer in inverted perovskite solar cells is prone to deformation, limiting long-term device stability. A bulk nano-heterointerface is designed to strengthen the binding force between molecules and spherical silicon oxide nanoparticles, increasing the interfacial contact area and improving the operational stability of perovskite solar cells.