Overcoming the Perovskite Photovoltaic Trilemma via Conjugated Polymer Electron Transport

Inverted perovskite solar cells increasingly require electron transport layers that combine efficient charge extraction with interfacial stability and scalable processing. Here, we highlight 2PB-T, a nonfullerene conjugated polymer that addresses these demands through coordinated molecular and interfacial design. The fused PBI units and conjugated polymer backbone create a molecularly organized interface that integrates efficient electron transport with interfacial stabilization through coordinated packing, energy-level alignment, and surface interactions. Small area devices reached a power conversion efficiency of 27.8%, with a certified maximum power point tracking efficiency of 27.3%. The same material delivered 24.4% efficiency in 20.6 cm² minimodules and 22.5% in 625 cm² modules. Under accelerated aging, devices retained 98.6% of their initial efficiency after 1752 hours, while encapsulated large area modules preserved 96.9% after 5900 hours of outdoor operation. These results show how polymer based interface engineering can connect high efficiency, operational durability, and practical manufacturability in perovskite photovoltaics.