High Open-Circuit Voltage–Fill factor product in perovskite solar cells enabled by ferroelectric heterojunction modulation

Overcoming the inherent limitations of perovskite-perovskite heterojunctions in simultaneously boosting built-in potential and suppressing non-radiative recombination remains a critical challenge in perovskite solar cells. Here, we introduce a ferroelectric-based heterojunction architecture that addresses this dual challenge through synergistic mechanisms. Firstly, the spontaneous polarization inherent to the ferroelectric-based heterojunction significantly amplifies the built-in electric field, enhancing charge separation and transport, thereby increasing open-circuit voltage from 1.16 to 1.21 V. Secondly, ferroelectric nuclei effectively regulate perovskite crystallization kinetics via dissolution-recrystallization modulation, effectively suppressing trap states and elevating fill factor from 83.6% to 86.8%. The champion devices achieve a power conversion efficiency of 26.62% (certified 26.07%) with an open-circuit voltage-fill factor product of 1.05 V, reaching 90.3% of the Shockley-Queisser limit. Furthermore, the modified devices demonstrate enhanced operational stability with over 85% efficiency reservation after 500 h of maximum power point tracking, charting clear pathways towards high-performance photovoltaic cells. Wu et al. report a strategy of incorporating either Dion-Jacobson phase or Ruddlesden-Popper phase ferroelectric perovskite with FAPbI3 to form bulk heterojunctions, increasing the open-circuit voltage-fill factor product and enabling single junction solar cells with an efficiency of 26.62%.