Carbon‐14 Perovskite Betavoltaics Reach Record 10.79% Efficiency

ABSTRACT Betavoltaic cells, a key type of nuclear battery, promise sustainable and autonomous power generation for critical applications, including implantable medical devices, space exploration, and edge AI systems; yet, their practical deployment has remained limited due to low energy conversion efficiency (ECE). Here, we demonstrate a perovskite‐based betavoltaic cell (PBC) incorporating formamidinium lead iodide (FAPbI 3 ) and carbon‐14 nanoparticles, achieving an unprecedented ECE of 10.79%. Our device features enhanced charge generation, with each incident β‐particle initiating electron avalanche multiplication, yielding over 4.0 × 10 5 carriers, resulting in a stable short‐circuit current of 10.60 nA cm −2 and an open‐circuit voltage of 76.92 mV. By employing methylammonium chloride additives and isopropanol‐assisted crystallization, we achieve defect‐suppressed perovskite films exhibiting significantly improved stability, allowing continuous operation exceeding 15 h. This study bridges the performance gap between theoretical predictions and practical implementation, establishing a scalable platform for reliable nuclear‐powered microelectronics and opening pathways to next‐generation energy solutions.