Breakthrough in Perovskite Solar Cells Achieves Record 27.17% Efficiency with Graded-Doped SnO2

Conventional n–i–p architecture, a robust platform for scalable perovskite photovoltaics, has long faced a stagnation in its steady-state efficiency, hovering around 26%. This performance ceiling has left it trailing behind its p–i–n counterparts, posing a significant challenge for the broader adoption of perovskite solar cell technology. The underlying reasons for this efficiency gap have remained elusive, prompting intensive research into the fundamental physics governing these devices. A recent groundbreaking study has now pinpointed the precise physical origin of these efficiency losses. Researchers uncovered that the persistent non-radiative recombination at the textured electron transport layer (ETL)/perovskite interfaces stems from a synergistic combination of two critical factors: band misalignment and electron accumulation at the buried interface. This dual challenge creates bottlenecks in electron extraction and leads to energy dissipation rather than conversion, directly limiting the overall power conversion efficiency. To effectively address this complex dual challenge, the research team developed an innovative solution: a continuously graded n+/n-doped SnO2 ETL. This advanced electron transport layer is fabricated using a sophisticated ligand-competitive binding strategy, which allows for spatially defined doping. The precise control over doping profiles is crucial, as it enables the creation of a built-in electric field within the material. This novel graded architecture is engineered to simultaneously tackle both identified problems. The built-in electric field and the graded doping profile work in concert to minimize band offset at the critical interface, ensuring a smoother energy landscape for electron movement. Concurrently, it significantly accelerates electron extraction from the perovskite layer, effectively suppressing the detrimental cross-interface recombination that previously hampered performance. The implementation of this cutting-edge ETL technology has yielded remarkable results. The resulting n–i–p perovskite solar cells (PSCs) achieved a certified steady-state power conversion efficiency (PCE) of 27.17%, with a peak efficiency of 27.50% in reverse scan. This represents the highest efficiency ever reported for n–i–p PSCs, surpassing the long-standing 26% barrier. Furthermore, the scalability of this strategy was convincingly demonstrated, achieving a PCE of 25.79% for a 1 cm² device and an impressive 23.33% for a perovskite module with a substantial 16.02 cm² aperture area. This pioneering work not only delivers a significant boost in perovskite solar cell efficiency but also establishes a generalized paradigm for energy-band engineering in metal-oxide transport layers. By successfully overcoming a fundamental efficiency bottleneck in conventional perovskite photovoltaics, this research paves the way for the development of even more efficient and scalable solar energy technologies, accelerating the transition towards a sustainable energy future.